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sci.electronics
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re a question about vac outlet wiring the truth i suggest that misc consumer house is a better forum for this several electricians a huge faq that adresses all the issues raised here wex
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how do di boxes work i m doing sound for a couple of bands around here and we need direct input boxes for the keyboards these are the little boxes that take a line level out of the keyboard and transform it into low z for the run to the mixer sadly they cost like or more each and i m going to need like or of them i looked inside one belonging to another band and it looks like just a transformer does anyone have any plans for building them perhaps in anderton s electronic projects for musicians book which i am having a hell of a time tracking down thanks a lot s ps post or email i read this group lancer wpi wpi edu modimidofrsaso mein kopf ist ein labyrinth mein leben ist ein minenfeld
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re analog switches balanced demodulators caadams atlas cs upei ca kenny adams writes hi instead of using a vdc supply for the try using a and volt supply i have some commercial audio equipment that uses this approach for ground referenced audio they use the volt supply as the logic ground in this case would the switch control voltages be v to turn the switch off and v to turn the switch on michael fulbright msf as arizona edu
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re a question about vac outlet wiring in article qids innebl chnews intel com crichmon sedona intel com chris richmond writes in article apr mprgate mpr ca vanderby mprgate mpr ca david vanderbyl writes in article apr ecsvax uncecs edu crisp ecsvax uncecs edu russ crisp writes i m considering modernizing some old wiring in my home and i need a little advice on outlet wiring several outlets are the old two prong type without the ground naturally the wire feeding these outlets is without the ground wire i noticed at the fusebox that some circuits have the with ground and that on these circuits the ground wire was tied to the same bus as the neutral white wire this is contrary to the electrical code and should be fixed well my house was built just last year and the breaker box is wired the same way there should be a connection of the ground wire to a ground in the breaker box there also should be a connection of the neutral wire to a ground in the breaker box there should be no other place in the building where such a connection occurs i e not in any of the outlet boxes the neutral white wire is a grounding conductor for the plug and is not safe to touch while the ground green wire is a protective ground and carries no current unless some kind of electrical fault has occurred it s safe to touch the protective ground but not to touch the grounding conductor because there is current in the grounding conductor its outlet box end will not be at the same ground potential as its breaker box end john whitmore
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re cable tvi interference in article vl b w w inqmind bison mb ca jim inqmind bison mb ca jim jaworski writes what happens when dvc digital videon compression is introduced next year and instead of just receiving squiggly lines on or channels we ll be receiving sqigglies on let s see channels eventually since the digital transmission schemes include error correction and concealment the performance remains about the same down to a very low carrier to noise ratio below which it degrades very quickly hence digitally compressed tv is supposed to be less susceptible to interference than amplitude modulated tv bill mcfadden tektronix inc p o box ms beaverton or bill tv tv tek com tektronix tv tv tek com bill phone how can i prove i am not crazy to people who are
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re where to buy parts or at a time the pricing of parts reminds me of something a chemist once said to me a gram of this dye costs a dollar it comes out of a liter jar which also costs a dollar and if you want a whole barrel of it that also costs a dollar i e they charge you almost exclusively for packaging it and delivering it to you the chemical itself in that particular case was a byproduct that cost almost nothing intrinsically michael a covington associate research scientist artificial intelligence programs mcovingt ai uga edu the university of georgia phone athens georgia u s a amateur radio n tmi
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7,106 |
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re electronic odometers i had the insturment panel go out in my car a lincoln contenintal which is a digital dash they replaced the whole thing with a dash thank god it was under the warrenty anyway the odometer was reading the exact milage from the old panel it must have a eeprom of some sort in it that is up dated seems to me that removing the battery would erase it but it doesn t so i guess they swapped the nvm chip non volitile memory and installed it in the new dash no they wouldn t let me have the old dash to tinker with wes
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re uninterruptible power supply in article nurden elaine ee und ac za nurden elaine ee und ac za dale nurden writes i m wanting to build a simple ups for my pc sustain the computer long enough to complete the current task and save to minutes should be enough i think though i don t really need to keep the monitor active i can try to remember what to do so maybe i can avoid a dc ac inverter and just use a battery to directly supply the motherboard and peripherals now there s a good idea all you need is amps dc for a few minutes and a good wetware memory was i using wp or autocad or i thought of the same idea myself a few days ago i ve got a fairly new car battery that i take along in my x when i go camping and it sits around useless when i m home i wish i could get a batteryless ups to use it with or use it with a heavy duty volt regulator to supply the pc but i guess you d need v and v and too more batteries an alternative would be to leave a amp battery charger hooked up to the battery and run a vdc to vac converter running all the time and when the power goes out voi la the vac converter keeps on running off the battery and then i could take the vac converter and my computer on the camping trips harry langenbacher harry neuron jpl mil jpl nasa gov fax concurrent processing devices group jet propulsion laboratory m s oak grove dr pasadena ca usa
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microphone pre amp low noise phantom powered i m looking to build a microphone preamp that has very good low noise characteristics large clean gain and incorportates phantom power volts dc for a pzm microphone i m leaning towards a good low cost instrumentation amplifier to maintain the balanced input from the microphone for its good cmrr internal compensation and because i can use a minimal of parts does anyone out there have any experience suggestions advice etc that they d like to pass on i d greatly appreciate it a l a n m a c a l u s o purple moon giants ali cns nyu edu e th st b nyc
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7,109 |
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re what to do with old k simms in article apr csx cciw ca u csx cciw ca g stewart beal writes in article netnews upenn edu jhaines eniac seas upenn edu jason haines writes i was wondering if people had any good uses for old k simms i have a bunch of them for the apple mac and i know lots of other people do to i have tried to sell them but have gotten no interest so if you have an inovative use or want to buy some simms i would be very interested in hearing about it one of the guys at work takes of them uses cyano acrylate glue to make five four wide panels then constructs a box with bottom to use as a pencil holder or if you ve got some entreprenuerial sp spirit get a cheapy clear plastic box mount the simm inside and sell it as a pet simm i m sure there are plenty of suckers out there who would go for it aaron
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re a question about vac outlet wiring olsen vetmed cvm uiuc edu aart olsen writes i noticed at the fusebox that some circuits have the with ground and that on these circuits the ground wire was tied to the same bus as the neutral white wire this is contrary to the electrical code and should be fixed sorry but this is exactly according to the nec no need to be sorry i blew it on this one at the main breaker box where there is a thick wire ground leading to the earth both neutral and ground are hooked to this bus in any other breaker box or an outlet box etc the ground and neutral must not be connected together
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re mysterious tv problem source llbgb utxdp dp utexas edu writes initial symptoms no picture or sound crt filament does not glow flyback ticking as described abovew discovered when hooked up the scope if strip is not putting out audio or video signals everything is making simple hz pulses horiz out transistor collector case of the to is a hz downgoing sawtooth with ca khz ring at front end guys what s going on here anyone seen this before what is happening is this you turn the tv on the horizontal output begins normal operation this powers up the high voltage and most of the rest of the circuitry a problem is sensed and the horizontal oscillator shuts down after it powers down the cycle repeats things to check first check for a shorted high power component your best bet is the vertical output transistor s or if there is one the voltage regulator the most common cause of this type of failure is too much current being drawn somewhere also look for shutdown circuits which your tv may or may not have if you can find one that is shutting down the horizontal oscillator then it shouldn t be too hard to find the problem from there
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re what are some good suppliers of chips in article qihcl ri usenet ins cwru edu ae cleveland freenet edu paul simundza writes anyone know of any good supplier s of chips one that could have almost any chip i need i don t want to hunt down all the chips i may need so it would be greatly appreciated if anyone knows of a good distributor thankyou paul unfortunately there are not too many retail outlets that ll stock just about every chip made the stuff they will stock are the ones that ll sell like standard dram s s s etc etc i e i cna t think of any one stop shopping store the closest you can get is to pick up a copy of byte magazine or the circuit cellar popular electronics and the like and flip through them distributors like wyle electronics hamilton avnet pioneer electronics etc etc don t normally deal with end users like ourselves where we only a couple of everything they only deal with people who buy by the hundreds or more each distributor represents and sells a variety of different non competing manufacturers what do i mean by this suppose abc electronics sells intel s it s a pretty good bet that they won t be selling any of amd s s or vice versa they also can obtain just about any chip you want from a manufacturer they represent who knows you might be lucky to be able to buy from one of them but i d be suprised if you do also bear in mind that the or qty prices they will charge you will be much greater than what a mail order outlet will charge my advice if you re gonna be designing anything try to stick with off the shelf stuff you re going to get stuck if you use too many esoteric parts sooner or later good luck aaron
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re ibm pc xt switch settings in article qk kcp bigbird hri com obrien bigbird hri com writes i just got an ibm pc xt with no documents its a true ibm and i was wondering if anyone had the definitions of the position dip switches sw sw number of drives drive drives drives drives sw sw type of display reserved x color mono mode x color mono mode mono x sw sw amount of memory on system board k chips k chips k k k k k k k k sw co processor installed sw loop on post
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need acs tutorial and or netlist examples i recently ftp d al s circuit simulator acs and i m looking for the tutorial which is mentioned in the users manual but not found there i don t have any experience constructing a netlist such as for spice and i need a little help the examples which come with acs aren t explanatory about the translation between schematic and netlist does anyone have the fabled tutorial or any other reference which could help me in constructing a netlist from a schematic diagram i also emailed al himself but received no response yet he s probably busy with his next release tim pillsbury internet tsp ccd harris com uunet uunet ccd harris com timothy pillsbury
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new mailserver soon utopia service for all those who are interested and would like to discuss the popular secret life and or other technical documentaries please email me as i am starting a newsgroup jolt gnu ai mit edu its not impossible just improbable johnp pro angmar uucp zaphod beeblbrox bl cleveland freenet edu n nig amsat org being a ham is so grand
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re source for carbide pc board drills in article c ejl lin news cis umn edu mike diack mike d staff tc umn edu writes in article c dgg ox wang com pvr wang com writes who sells the special carbide drills used to drill pc boards i am looking for sizes smaller than or would be good best deal i ever saw on carbides was at eli electronics cambridge mass quite close to mit drills for a box of eli are in the boston fone book actually i think they are all their phone number is and i will probably have some over at the mit flea this sunday mike michael l ardai n ist teradyne atg boston ardai maven dnet teradyne com
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cheap lcd panels seeking info attention hardware hackers and bargain seekers i just bought a x pixel lcd panel for uk pounds i have a datasheet for a similar panel but i m looking for proper data if anyone can help with locating data for this device before i start with the routine on the phone to hitachi and rummaging through the library then i ll pass on the source type lm hitachi resolution w x h so can do x chars on x matrix bought from greenweld electronics ltd park rd southampton so tb uk tel fax email compuserve nb i only just bought this i don t even know if it works price was uk pounds including vat which isn t payable if you re outside the ec thanks for any info chris chris hand lecturer internet mail cph dmu ac uk dept of computing science voice x de montfort university the gateway fax fidonet leicester uk le bh linux free unix for ibm pcs
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re r s battery of the month club in article jwaterma apr jade tufts edu jwaterma jade tufts edu jason waterman writes i talked to a friend who works for radio shack and he said the deal with the red batteries were that they had too much lead in them condidering the red batteries had a life cycle shorter than a mayflies i think the epa was worried about all those batteries being dumped out pardon me but why would carbon zinc cells have any lead in them at all scott
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re do analog systems need ground planes engp nusunix nus sg soh kam yung writes i understand the need for a ground plane in a digital system however i would like to know if such a ground plane is also necessary in an analog system note this ground plane will not be connected except at one point to the signal ground i keep getting conflicting answers over this does having a ground plane in an analog system help reduce noise also my system only deals with low frequency signals up to hz only well one reason for getting conflicting answers is that it depends on what you want the ground plane to do a continuous conductor is a good electrostatic shield do you have signals on your board that need shielding rom other things this shielding won t do much good for magnetic fields unless you make it continuous around the circuit to be shielded like a faraday cage the flip side of the coin if you are working with very high impedances you could end up with capacitances to the gound plane that cause problems you aren t likely to encounter this at hz but at khz it can be a real problem one that bit me once
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re what to do with old k simms in article c jch frc ulowell ulowell edu wex cs ulowell edu writes in article apr csx cciw ca u csx cciw ca g stewart beal writes i was wondering if people had any good uses for old k simms i have a bunch of them for the apple mac and i know lots of other people do to i have tried to sell them but have gotten no interest we use them as christmas tree decorations the cat doesn t eat these yes but they don t look appropriate i much prefer used tubes on my tree scott
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re microphone pre amp low noise phantom powered in c jjj tf cmcl nyu edu ali cns nyu edu alan macaluso writes i m looking to build a microphone preamp that has very good low noise characteristics large clean gain and incorportates phantom power volts dc for a pzm microphone i m leaning towards a good low cost instrumentation amplifier to maintain the balanced input from the microphone for its good cmrr internal compensation and because i can use a minimal of parts does anyone out there have any experience suggestions advice etc that they d like to pass on i d greatly appreciate it a l a n m a c a l u s o purple moon giants ali cns nyu edu e th st b nyc without doing anything really tricky the best i ve seen is the burr brown ina their databook shows a good application of this chip as a phantom power mic pre josephson engineering san jose california microphones tel fax instrumentation email david josephson com ftp info from rahul net pub davidj
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re network zjoc hou amoco com jack o coats writes the same folks now have out lbl little big lan for i think you get it for if you already own network lbl works with arcnet parallel ports and serial ports in any combination for up to or so nodes lbl now offers ethernet support also although presently it is limited to ne ne style boards lbl owners can get an update for ray berry kb ht ray ole cdac com rjberry eskimo com compuserve com
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where to find cheap lcd displays sci e e netters i am setting out to build and market a small electronic device that requires an lcd display all of the analog electronics are working fine i have ordered a pic ice not vice versa since the pics are so cheap and low power but i am having a devil of a time finding any lcd displays in the digit range that are priced as low as i need i am looking for somthing in the range of in quantities of about mainstream distributors like almac cannot help me without a part number or when they do look around for something in their line they find a digit lcd even digikey s cheapest offering is in quantity i know lcd displays like this must exist because i see whole calculators for sale for meaning the retailer probably buys it for and the wholesaler probably gets it for or so this includes assembly labor packaging sales transportation import duties the case and keyboard the pc board the processor chip the solar cell and the lcd the lcd can t cost much if anyone could put me in touch with some manufacturers and or distributors that handle such things i would be much obliged joe betts betts netcom com p s i have tried tearing apart several cheap consumer devices that have lcds only to find that the lcds are unlabelled has anyone else had better luck with this strategy
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amplifier into cd rom earphone plug we have a sun cd rom drive which i would like to play audio cd s in i have an old watt amplifier which works fine when connected to a junk walkman style am fm radio this amp ties the common path of the earphone connection to ground however it doesn t work with my sony walkman cassette player or the cd drive it produces of loud low frequency tone obviously sony doesn t ground the earphone output common does anyone have specs on the cd drive s output will an audio transformer help what are others using to play there cd s in the sun drive so that more than one can listen thanks for the help bill morrow clinical neurosciences university of calgary e mail morrow cns ucalgary ca voice fax hospital drive nw calgary alberta canada t n n
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re radar detector detectors in apr vdoe vak ed edu ragee vdoe vak ed edu randy agee writes so the questions are what do the radar detector detectors actually detect would additional shielding grounding bypassing shield stray rf generated by a radar detector or is the rf actually being emitted by the detector antenna are any brands quieter than others ok so your a ham well tune in mhz or khz these numbers sound like some you have herd before thats right you guessed it they are common if numbers every super het receiver has a local oscillator s which generates an if this is what your detector detector is detecting the local oscillator some of these have two or more local oscillator which generate more ways to receiver you if you want to receiver something at say ghz you must generate a local oscillator signal of ghz mhz your local osc frequency this mhz if is then fed into a normal agc ckt the detector is keyed uppon the agc voltage your mileage may vary since the agc is a negative feed back device a positive voltage sets off a i think you get the picture
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subliminal message flashing on tv hi i was doing research on subliminal suggestion for a psychology paper and i read that one researcher flashed hidden messages on the tv screen at ths of a second is that possible i thought the maximum rate the tv was even capable of displaying images was th of a second or th of a second for an image composed of only odd or even scan lines rich kennehra logic camp clarkson edu
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sci.electronics
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telcom wiring question need help i ve got two lines coming into my apartment two different telephone numbers when i ordered the second line installed instead of bringing out another wire bundle the telco just connected up to my yellow and black wires so i have one line on red green and the other on yellow black today i was monitoring the voltage on both lines i had a voltmeter across the red and green and read back volts i then lifted up the receiver on my second line black yellow wires the voltage dropped to volts on the first line red green wires i repeated this experiment with the second line monitoring black yellow and lifting the handset off the cradle on the red and green line it also dropped to volts why is this i thought these were separate lines next i went to the block and disconnected the blue and white lines coming in from the telco cable i then disconnected all the phones in my apartment and went back to the block and did some resistance measurements both lines read open i ll appreciate any help on this is this considered normal guy urbina urbina novax llnl gov
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beam robot olympic games next week in toronto one week to the robot olympic games fire up the mechanoids for combat and come on down competitors please note that there has been a slight change the registration desk will now be in the forward building of the science centre rather than in the main competing hall when you arrive please go to this desk those that have pre registered by real mail will find badges waiting is all see you here mark tilden glitch m f c f hardware design lab u of waterloo ont can n l g ext my opinions you hear mine mine mine mine mine ah hahahahahahahahaha
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re electronic odometers was used bmw question in article apr slcs slb com dcd se houston geoquest slb com dan day writes that s scary if there s a way to set an arbitrary mileage figure into the odometer you can t trust any odometer reading even if you can prove that the odometer itself is the same one that came on the car originally i was wondering if anyone can shed any light on just how it is that these electronic odometers remember the total elapsed mileage what kind of memory is stable reliable enough non volatile enough and independent enough of outside battery power to last say years or more in the life of a vehicle i m amazed that anything like this could be expected to work for this length of time especially in light of all the gizmos i work with that are doing good to work for months without breaking down somehow side question how about the legal ramifications of selling a used car with a replaced odometer that starts over at miles after say k actual miles looks like fraud would be fairly easy for the price of a new odometer you can say it has however many miles you want to tell the buyer it has thanks for any insight kim greer duke university medical center klg orion mc duke edu div nuclear medicine pob voice durham nc fax
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data pods b for hp logic analyzer a anyone out there in netland have a spare data pod or two from an old a hewlett packard logic analyzer if you do i d like to buy it off of you the pod s part number is b as a side note anyone know of any good surplus dealer or other organization that would carry wayward logic analzer pods thanks a byte tod tod cco caltech edu
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re exploding tv sounds like the picture tube lost vacuum this would cause the filament to ignite and could actually turn the tube from a vacuum to a pressure vessel followed by an explosion when the neck assembly mostly likely cracked to begin with blows off during the whole sequence of events the other circuits may continue functioning which accounts for not losing sound
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scope questions greetings i ve been seeing the word storage mentioned around oscilliscopes but i m curious what does it mean if my life depended on it i d say that it s a scope that uses long persistance phosphor to keep the successive taces on the screen for some unit of time store them do i get to live also i ve been shopping for a decent used old scope since my tek a portable not and my heathkit o are all single trace and i need more like or and at least mhz maybe during my shopping at hamfests etc i ve run into the problem of old scope terminology i can imagine what a mainframe and plug in are but some things like the above storage coax input hey where do i get a probe that fits this i had to fiddle with mine for a week before i got anything resembling a good trace they all come with bnc connectors unblanking huh and oh just like my manuals many changes were made along the way to the schematic scopes even with identical model numbers have different better response performance than others how can i pick the better one does the rule of the higher sn the better apply take care filip i ll buy a vowel gieszczykiewicz best e mail fmgst pitt edu all ideas are mine but they can be yours for only so respond now i live for my ee major winsurfing programming sca and assorted dreams mb drive linux has mb and ms dos has mb ms dos is worried
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re cd player going wonky advise needed in article apr nessie mcc ac uk sl nessie mcc ac uk stuart lea writes hello i ve got a problem with my cd player sony cdp in that it refuses to play discs more than a minor inconvenience the player itself doesn t recognise that there is a disc in it s an intermitant problem but one that is becoming more frequent is this a common problem with older cd players and if so what can be done to rectify it if there is no obvious answer how can i begin to start fault finding to start off with how does thet mach recognise that there is a disc in in the first place my experience is that the cd drawer becomes a bit loose and the cd either skips or can t be read try seeing if all the screws that hold down the drawer assembly are tightened properly other than that my next guess would be one of the motors hope this helps dave haans laurentian university sudbury ontario
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re adcom cheap products mdonahue amiganet chi il us mike donahue writes i do not know much about adcom mobil audio products but i do know for a fact that adcom does not make its own high end home audio equptment and that of it comes directly out of tiawan like most high volume manufacturers adcom has most of its pc boards assembled off shore in their case mostly in the far east final assembly and testing are done in east brunswick the products are and have always been designed entirely in the us by their own staff and by audiophile gurus like walter jung adcom also tends to prefer american and european components over their japanese far east equivalents off shore assembly is one reason that adcom is able to make products that perform as well as those from people like audio research and van alstine and better than hafler and forte but at a much lower cost of course if your musical diet consists mostly of rock you might prefer components from kenwood or pioneer roger williams most great discoveries are made rogerw world std com by accident the larger the consulting engineer funding the longer it takes to middleborough mass have that accident
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re telephone on hook off hok ok circuit in article apr bnr ca moffatt bnr ca john thomson writes just a thought of mine here since an on hook line is aprox v and off hook it usually drops below how about an led in series with a zener say around v on hook led on off hook led off would this work if anyone tries tried it please let me know aye there s the rub if you draw enough current to light an led the equipment at the phone company will think you ve gone off hook in the on hook state you re not supposed to draw current which means you should just use your digital voltmeter you can use an old vom but the phone company equipment can detect that and might think there s something wrong with the cable look guys what s the problem here if you want a light that goes on when the phone is off hook all you need it to run it in series with the line as i mentioned in my previous post if you want a light that goes on when the phone is on hook all you need is a voltage threshold detector if you re going to do the series diode thing which is the easiest just make sure that the led can take the current i can t recall it off hand but it s something like ma or more careful now folks also consider the vac hz that is forced on ring and tip when the phone s supposed to ring even with a simple zener and led setup you might end up with some carbon real quick whatever scheme you use make sure you ve got at least v rated components on the frontend also remember that if i m not mistaken the phone line is a ohm equivalent circuit any current you draw from the v or so gets dropped across that ohms that s fine until you re down to roughly v when ma bell considers it to be off hook but dropping it that far down is probably a big no no the easiest implementation to accomplish the above tip rectifier resistor diode v zener resistor v led ring this is only a suggestion go ahead and blow holes in it but you get the idea choose a high efficiency led so you don t need much current to get it to light up choose values for the other components as required aaron
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re uninterruptible power supply in article qk inn hp col col hp com cab col hp com chris best writes i m no expert at ups s but you said something that made it sound like you didn t realize something on a typical ups well on ours anyway there is no switchover from ac to dc all the protected equipment is always running from the batteries via an inverter with the usual condition of also having them on charge if the power fails big deal the computers never see it until the batteries start to droop but there s something like car sized batteries in that cabinet so it takes a while if you were gonna run the guts on straight dc instead of an inverter why not do it all the time then there d be no switchover to screw things up and no having to sense the failure fast just keep the dc on charge when the power is on and it ll be there in zero time when you need it actually it s a bit more complicated than that i sounds to me your ups takes in ac rectifies it to dc to charge the batteries and then takes the battery dc and chops it to ac again feeding your equipment this approach is the easiest and cleanest way to switchover from the mains to battery once your power kicks out since as you mentioned nothing will know about what happened down the line another way to do the ups scheme is to use the mains until you lose power and then kick in the battery backup with it s inverter to replace the lost power the problem here is the switchover time and you ve got to resync the ac in no time flat unfortunately most everything is built around the assumption that ac is available so the ups guys have to provide and ac output to be usable ya sorta have to make it work with what there already similar story with our telephone system it was first invented back in the s we re still using the same damn system media as they did back then if i have a phone from back then i can assure you it ll work on today s phone system it costs too much to overhaul everyone to a new system so they make it work with what is out there
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re exploding tv in article qk hj qos vtserf cc vt edu prasad vtaix cc vt edu prasad ramakrishna writes i had a ge emerson color tv for about years and one fine day while we were watching something i doubt if the program was the cause we heard a mild explosion our screen went blank but there was sound so we thought oh we have special effects on the program but soon the sound stopped and smoke started to appear at the back of the tv the brilliant ees we are we unplugged the tv and called customer service only to be thrown around by please hold i will transfer u to blah blah finally we abandoned the idea of trying to fix the tv and got a new one we wanted a bigger one too after all the story what i wanted to know is is my problem an isolated incident or a common one i recall reading about russian tvs exploding but not here in the us why would the picture tube explode or even smoke i still have the left over tv set i might dig into it this summer any idea where i can get parts for these things probably will cost more than tv heh heh heh heh i laugh because i have the same damn tv and it did the same thing actually it is a goldstar but it s essentially the same tv and electronics just a different face plate and name fortunately tv tubes don t explode i d think the tv mfrs want to make this possibility remote as possible if at all they ll implode and the glass that blows out would be the result of the glass boucing off the back of the tube due to the implosion in any case don t kick it around i fixed the tv after getting a hold of some schematics it turned out to be a blown w resistor feeding the flyback transformer i guess the original resistor was a bit too small to dissipate the heat it created burning itself out i checked to make sure the flyback wasn t shorted or anything first oh luckily i had a resistor handy lying around that had just the right value for what i needed i can t see it being more than cents well needless to say the tv still works today so go get a set of schematics and have some fun just don t get shocked poking around the flyback
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re adc card for computer in article qi e b e lll winken llnl gov you say i would like to digitize the output of a squid magnetometer range v to v and do digital signal processing in a computer say a macintosh ii or a pc i would like a good bit adc with good linearity and a high conversion speed at least khz preferably khz other concerns must i use an adc external to my computer to avoid digital noise feedback into my sensitive squid electronics might be a good idea the resolution you requested is about mv in order to get what you ve paid for noise level better be lower than that it is kind of hard to do it in a noisy box like you can expect inside a pc before you pay for a pc card test it out by sampling a low distortion sine wave i think there is a sine wave on a cd digital domain there are possibly other low thd sources run the digitized waveform through a fft transform and take alook at the noise floor on the spectrum that s should give you a good indication of the design that s what i am doing to test a data acquistion system i have designed i got the idea from maxim data sheet if you can live with bit resolution i would recommend looking at the max from maxim it is a high speed khz complete sampling a d with dsp interface the input range is v and it uses a serial interface which can easily be optically isolated from the computer to elinimate a major noise source the analog design guide i got from them shows a db noise level they claim a db max typ thd looks pretty good for the pieces a evaluation kit is available might want to give these nice folks a call or fax and ext for application assistance this assumes that you can build your own das and write your own software hey you can get the max as a free sample just by calling the i would appreciate discussion of your personal experience with a mac or pc based adc system i would recommend you to find out the resolution that can be gotten out of your system by looking at the noise level otherwise you might be throwing out your money charles cunningham cec imager llnl gov k c lee elec eng grad student i have no connection with maxim except i do in general recommend companies that give samples to students to others i feel they deserve that for being nice to me
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re what to do with old k simms in article netnews upenn edu jhaines eniac seas upenn edu jason haines writes i was wondering if people had any good uses for old k simms i have a bunch of them for the apple mac and i know lots of other people do to i have tried to sell them but have gotten no interest so if you have an inovative use or want to buy some simms i would be very interested in hearing about it the most practical use i ve seen for them is as key ring ornaments johnh
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re radar detector detectors in article oxenreid chaos cs umn edu oxenreid chaos cs umn edu writes in apr vdoe vak ed edu ragee vdoe vak ed edu randy agee writes so the questions are are any brands quieter than others yes some radar detectors are less detectable by radar detector detectors look in car and driver last months should do they had a big review of the better detectors and stealth was a factor steven m knapp computer engineering student sknapp iastate edu president cyclone amateur radio club iowa state university ames ia usa durham center operations staff
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re making copy of a video tape there are devices you can buy and or make look in radio popular electronics mags for the devices if all else fails you can build one using the curcuit design from the dec issue of radio electronics my very favorite ad for such a device is on the back of the latest damark catalog quoting from memory big flashy type dual deck vcr copies any tape even those that are copy protected and underneath the ad in very small print this device is not intended for making illegal copies of copyrighted material gordon s hlavenka cgordon vpnet chi il us vote straight ticket procrastination party dec rd
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re electronic odometers was used bmw question in article apr porthos cc bellcore com dje bmw nosubdomain nodomain don eilenberger writes in article apr nimbus com jimiii nimbus com jim warford writes there are two simple procedures for alterating any odometer mechanical driven odometer remove the speedo cable from the transmission attach a drill and run at max speed until the speedo turns over continue until the desired mileage is reached electronically driven odometer remove the sensor wire from the sensor attach the calibration out signal from an oscope to the wire run until the speedo turns over and attains the desired mileage dear faster i kinda wonder have you ever tried version on what since the sensor wire on a bmw feeds also into the computer and we don t know what signal voltage is expected from it bad things could happen also since we don t know the pulse rate we may damage the analog part of the speedo yes bmw uses a combined instrument speed in analog trip and total milage is digital with the needle pegged up against the mph stop just a thought you ve got the oscilliscope so you connect it up to the sensor wire and measure this stuff that way you know what it expects matthew t russotto russotto eng umd edu russotto wam umd edu some news readers expect disclaimer here just say no to police searches and seizures make them use force not responsible for bodily harm resulting from following above advice
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re picking up cable tv with an aerial in article gyjx b w w inqmind bison mb ca dino inqmind bison mb ca tony stewart writes jfsenior unix tcd ie john senior writes recently i discovered that it was possible to receive cable tv through the telescopic aerial on the top of my tv the nearer this aerial is moved to the cable which i am not connected to which runs under the eaves of the house the better the signal now i was wondering how can i improve the signal is it possible to improve the signal significantly some channels cable egress or emanations if you will are being radiated at free space impedance from cables that may be harmonically realated to certain channels and therfore the standing waves at wave will transfer efficiently also your antenna a loose monopole is also harmonically tuned and will be more efficient at wavelength multiples your best bet for this research is to use a tuned yagi antenna to get the gain you need std tv roof antenna type the dipoles should be parallel to the radiating cable a pre amp doesn t help significantly in my experience in most cases dino inqmind bison mb ca the inquiring mind bbs winnipeg manitoba wow what a concept does anybody want to speculate on how this non connection would fit into the theft of cable services laws it seems to me that unless this case is specifically written into the legislation that the cable company would not have a leg to stand upon in court does anybody out there have any specific legal knowledge on this jim ritterbusch ritterbus wcsu ctstateu edu or ne radiomail net temp rf there is an art the guide says or rather a knack to flying the knack lies in learning how to throw yourself at the ground and miss
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hard drive component costs does anyone have some information on the relative fraction of the final cost of each component in an average hard drive for instance i m pretty sure the heads and the platters are the most expensive parts with the assembly costs running a close third cost of the electronics is likely in the noise any hard numbers or percentage thanks kevin doherty e systems melpar division doherty melpar esys com principal engineer falls church va x kevin doherty e systems melpar division doherty melpar esys com principal engineer falls church va x
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re radar detector detectors alee bmerh bnr ca louis leclerc writes in article oasys dt navy mil you write va ct wash dc and i think bc canada where i ve heard they actually use radar detector detectors nope not in british columbia detectors are legal here in bc i ve even got one in alberta and ontario they re illegal and detection devices are sometimes used i ve heard the police in ontario prefer a much more direct method of detection just trigger the radar gun watch for people slamming on the brakes and search the car david lee leex sfu ca they are illegal here in manitoba as well though i don t know what methods are used to detect them it has always amazed me with the way the laws work it is not illegal to sell them here in manitoba only to have them within a vehicle last i heard they don t have to be installed to be illegal victor inqmind bison mb ca the inquiring mind bbs winnipeg manitoba
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re a question about vac outlet wiring in article apr ecsvax uncecs edu crisp ecsvax uncecs edu russ crisp wrote hello i m considering modernizing some old wiring in my home and i need a little advice on outlet wiring several outlets are the old two prong type without the ground naturally the wire feeding these outlets is without the ground wire i noticed at the fusebox that some circuits have the with ground and that on these circuits the ground wire was tied to the same bus as the neutral white wire so here s my question it seems to me that i d have the same electrical circuit if i hooked the neutral d d d d d d d d d d da jumper from the neutral over to the ground screw on new three prong grounding outlets what s wrong with my reasoning here first it will not pass a national electrical code inspection secondly the neutral wire is current carrying and the ground wire shouldn t be or only during a fault condition the reason the neutral and ground are tied together in the panel is the tranformer on the power pole has a grounded center tap secondary with the grounded center tap the neutral this gives v to neutral ground from each side of the transformer and v across the transformer so in effect the neutral and ground should be at the same potential mark e kilpela email mkilpela mtu edu michigan technological university school of technology
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what do nuclear site s cooling towers do i really don t know where to post this question so i figured that this board would be most appropriate i was wondering about those massive concrete cylinders that are ever present at nuclear poer sites they look like cylinders that have been pinched in the middle does anybody know what the actual purpose of those things are i hear that they re called cooling towers but what the heck do they cool i hope someone can help
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re a question about vac outlet wiring in article apr ecsvax uncecs edu crisp ecsvax uncecs edu russ crisp writes i m considering modernizing some old wiring in my home and i need a little advice on outlet wiring several outlets are the old two prong type without the ground naturally the wire feeding these outlets is without the ground wire i noticed at the fusebox that some circuits have the with ground and that on these circuits the ground wire was tied to the same bus as the neutral white wire so here s my question it seems to me that i d have the same electrical circuit if i hooked the jumper from the neutral over to the ground screw on new three prong grounding outlets what s wrong with my reasoning here no no nooo the ground green wire is for safety no current is supposed to flow in it under normal conditions this means that there s normally no voltage drop in it either it is supposed to be safe to touch the ground wire even if you re grounded in some other way at the same time the neutral white wire is as dave vanderbyl correctly said the return for the hot wire since current flows in it there s a voltage drop if you plug a heavy load into a properly wired grounded outlet you can commonly measure a volt or so of difference between neutral and ground they are supposed to be connected together at the breaker panel but nowhere repeat nowhere else well almost there are strange exceptions for things like sub panels what you can do if you want three prong outlets without additional wiring is to use a gfci outlet or breaker but the outlet will be cheaper in fact depending on where you are putting your new outlet s a gfci may be required there is a faq on electrical wiring posted regularly to rec woodworking and news answers it goes into great detail on these issues including gfcis and you should probably read it before asking any more questions i ll mail a copy to you append a copy here and will ask the writers to cross post it here in the future jamie hanrahan kernel mode systems san diego ca internet jeh cmkrnl com uucp uunet cmkrnl jeh cis
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electrical wiring faq was a question about vac outlet wiring since electrical wiring questions do turn up from time to time on sci electronics and the answers aren t always apparent even to those skilled in electronics i am hijacking the following faq and posting a copy here i ve asked the writers to cross post to sci electronics in the future jeh cmkrnl com x news cmkrnl news answers newsgroups misc consumers house rec woodworking news answers misc answers rec answers subject electrical wiring faq message id wirefaq ecicrl from clewis ferret ocunix on ca chris lewis date apr gmt reply to wirefaq ferret ocunix on ca wiring faq commentary reception followup to poster expires may gmt organization elegant communications inc ottawa canada summary a series of questions and answers about house wiring supersedes wirefaq ecicrl lines archive name electrical wiring last modified sun feb est frequently asked questions on electrical wiring steven bellovin smb ulysses att com chris lewis clewis ferret ocunix on ca comments to automatic if you reply to this article wirefaq ferret ocunix on ca this faq is formatted as a digest most news readers can skip from one question to the next by pressing g answers to many other topics related to houses can be obtained from the misc consumers house archive send an empty piece of mail to house archive dg rtp dg com for information changes to previous issue marked with in left column watch particularly for new in the questions list for new or substantively changed answers note that this is now a registered faq cross posted to news answers and should appear in the faq list of lists subject questions answered in this faq introduction disclaimers what is the nec where can i get a copy what is the cec where can i get a copy can i do my own wiring extra pointers what do i need in the way of tools what is ul listing what is csa approval are there any cheaper easier to read books on wiring inspections how and what why should i get my wiring inspected my house doesn t meet some of these rules and regulations a word on voltages what does an electrical service look like what is a circuit grounding versus grounded versus neutral what does a fuse or breaker do what are the differences breakers can t i use fuses what size wire should i use where do these numbers come from what does mean what is a wirenut marrette marr connector how are they used what is a gfi gfci where should gfcis be used where shouldn t i use a gfci what is the difference between a gfci outlet and a gfci breaker what s the purpose of the ground prong on an outlet then why is one prong wider than the other polarization what kind of outlets do i need in a kitchen where must outlets and switches be in bathrooms what is romex nm nmd what is bx when should i use each should i use plastic or metal boxes junction box positioning can i install a replacement fixture what does it mean when the lights brighten when a motor starts what is phase power should i use it can i get it in my house is it better to run motors at or what is this nonsense about hp on v a circuits how do i convert two prong receptacles to three prong are you sure about gfcis and ungrounded outlets should the test button work how should i wire my shop underground wiring aluminum wiring i m buying a house what should i do what is this weird stuff old style wiring where do i buy stuff subject introduction disclaimers although we ve done a fair bit of wiring we are not electricians and we cannot be responsible for what you do if you re at all uncertain about what is correct or safe don t do it contact someone qualified a licensed electrician or your local electrical inspector electricity is no joke mistakes can result in shocks fires or electrocution furthermore our discussion is based on the u s national electrical code nec and the canadian electrical code cec to the best of our abilities we have confirmed every detail with the electrical code but we don t quote sections simply to keep this thing readable if you think we re wrong we invite you to correct us but please quote references the nec and the cec do not in and of themselves have the force of law many municipalities adopt it en toto others however do not check your with your local building department and provincial hydro inspection offices in canada to find out what applies in your area also your local electrical utility may also have special requirements for electrical service installation bear in mind too that we say here applies primarily to ordinary single family residences multi family dwellings mobile homes commercial establishments etc are sometimes governed by different rules also note that contrary to popular belief in the u s and in some parts of canada canada is not a wholly owned subsidiary of the u s consequently the nec does not apply in canada lots of things are the same including voltages line frequencies and the laws of physics but there are a number of crucial differences in the regulations where we can we ve noted them flagging the relevant passages with nec or cec remember that the cec and nec are minimal standards it is often smart to go beyond their minimal requirements subject what is the nec where can i get a copy the nec is a model electrical code devised and published by the national fire protection association an insurance industry group it s revised every three years the version has been released you can buy a copy at a decent bookstore or by calling them directly at the code exists in several versions there s the full text which is fairly incomprehensible there s an abridged edition which has only the sections likely to apply to most houses and there s the nec handbook which contains the authorized commentary on the code as well as the full text that s the recommended version unfortunately there s no handbook for the abridged edition and the full handbook is expensive us plus shipping and handling subject what is the cec where can i get a copy the canadian standards association is an organization made up of various government agencies power utilities insurance companies electrical manufacturers and other organizations the csa publishes csa standard c which is updated every two or three years each province adopts with some amendments this standard and publishes a province specific code book since each province publishes its own slightly modified standard it would be somewhat confusing to obtain the csa standard itself in this faq cec really means the appropriate provincial standard in particular this faq is derived from the ontario hydro electrical safety code th edition which is in turn based on csa c th edition while differences exist between the provinces an attempt has been made to avoid specific to ontario detail the appropriate provincial code can be obtained from electrical inspection offices of your provincial power authority in ontario it s ontario hydro the ontario hydro book isn t overly fat it s about c and includes mailed updates i hear that these standards are somewhat easier to read than the equivalent nec publications don t bother asking in quebec diy wiring is banned throughout the province subject can i do my own wiring extra pointers in most places homeowners are allowed to do their own wiring in some they re not check with your local electrical inspector most places won t permit you to do wiring on other s homes for money without a license nor are you permitted to do wiring in commercial buildings multiple dwellings eg duplexes are usually considered semi commercial or commercial however many jurisdictions will permit you to work on semi commercial wiring if you re supervised by a licensed electrician if you can find one willing to supervise if you do your own wiring an important point do it neat and well what you really want to aim for is a better job than an electrician will do after all it s your own home and it s you or your family that might get killed if you make a mistake an electrician has time pressures has the skills and knows the tricks of the trade to do a fast safe job in this faq we ve consciously given a few recommendations that are in excess of code because we feel that it s reasonable and will impress the inspector the inspector will know that you re an amateur you have to earn his trust the best way of doing this is to spend your time doing as neat a job as possible don t cut corners exceed specifications otherwise the inspector may get extremely picky and fault you on the slightest transgressions don t try to hide anything from the inspector use the proper tools ie don t use a bread knife to strip wires or twist wires with your fingers the inspector won t like it and the results won t be that safe and it takes longer and you re more likely to stick a hunk of ga wire through your hand that way don t handle house wire when it s very cold eg below c or f thermoplastic house wire particularly older types become very brittle subject what do i need in the way of tools first there s the obvious a hammer a drill a few screwdrivers both straight and phillips head if you re lucky enough to live in canada or find a source of csa approved devices you need robertson square recess screwdrivers and instead of phillips for drilling a few holes a or spade bit and or electric drill will do if you re doing a lot or are working with elderly lumber we recommend a drill right angle drills are wonderful can be rented and or screw point auger drill bits these bits pull you through so they re much faster and less fatiguing even in year old hardwood timbers screw driver bits are useful for drills expecially if you install your electrical boxes using screws drywall screws work well for stripping wire use a real wire stripper not a knife or ordinary wire cutters don t buy the k mart combo stripper crimper and bottle opener types you should expect to pay to for a good plier type pair it will have sized stripping holes and won t nick or grab the wire it should be easy to strip wire with it one model has a small hole in the blade for forming exact wire loops for screw terminals there are fancier types autostrip cut but they generally aren t necessary and pros usually don t use them a pair of diagonal side cutter pliers are useful for clipping ends in constricted places don t use these for stripping wire you will need linesman pliers for twisting wires for wire nuts you should have a pair of needle nose pliers for fiddling inside boxes and closing loops but it s better to form wire loops with a loop former hole on your wire stripper more accurate if you re using non metallic cable get a cable stripper for removing the sheath or do what some pros do they nick the end of the sheath grab the ground wire with a pair of pliers and simply rip the sheath back using the ground wire as a zipper and cut the sheath off you shouldn t try to strip the sheath with a knife point because it s too easy to slash the insulation on the conductors apparently stanley utility knives fitted with linoleum cutters hooked blades can be used to strip sheath but there is still the possibility that you ll gouge the conductors for any substantial amount of work with armored cable it s well worth your while to invest in a rotary cable splitter us hack saws are tricky to use without cutting into the wire or the insulation three prong outlet testers are a quick check for properly wired outlets about multimeters tell you more but are a lot more expensive and probably not worth it for most people a simple voltage sensor which can detect potential through an insulated wire not supplying any devices is extremely helpful they cost about us at radio shack you should have a voltage detector to check that the wires are dead before doing work on them neon bulb version are cheap and work well if you get more serious a audible alarm type is good for tracing circuits without a helper though i ve been known to lock the drill on and hit breakers until the scream stops for running wires through existing walls you need fish tape often two tapes are needed though sometimes a bent hanger or a length of thin chain will suffice fish tapes can be rented electrical tape lots of it seriously a good and competent wiring job will need very little tape the tape is useful for wrapping dicy insulation in repair work another use is to wrap around the body of outlets and switches to cover the termination screws i don t do this but drywall contractors prefer it to prevent explosions when the drywall knife collides with a live outlet that has no cover plate subject what is ul listing the ul stands for underwriters laboratory it used to be an insurance industry organization but now it is independent and non profit it tests electrical components and equipment for potential hazards when something is ul listed that means that the ul has tested the device and it meets their requirements for safety ie fire or shock hazard it doesn t necessarily mean that the device actually does what it s supposed to just that it probably won t kill you the ul does not have power of law in the u s you are permitted to buy and install non ul listed devices however insurance policies sometimes have clauses in them that will limit their liability in case of a claim made in response to the failure of a non ul listed device furthermore in many situations the nec will require that a wiring component used for a specific purpose is ul listed for that purpose indirectly this means that certain parts of your wiring must be ul listed before an inspector will approve it and or occupancy permits issued subject what is csa approval every electrical device or component must be certified by the canadian standards association before it can be sold in canada implicit in this is that all wiring must be done with csa approved materials they perform testing similar to the ul a bit more stringent except that csa approval is required by law again like the ul if a fire was caused by non csa approved equipment your insurance company may not have to pay the claim in canada there is a branch organization of the ul called ulc ul of canada ulc does not have power of law and seems to be more a liason group between the csa and insurance companies subject are there any cheaper easier to read books on wiring usa the following three books were suggested by our readers residential wiring by jeff markell craftsman books carlsbad ca for isbn practical electrical wiring residential farm and industrial based on the national electrical code ansi nfpa herbert p richter and w creighton schwan mcgraw hill book co wiring simplified h p richter and w c schwan park publishing co try to make sure that the book is based on the latest nec revision which is currently canada p s knight authors and publishes a book called electrical code simplified there appears to be a version published specific to each province and is very tied into the appropriate provincial code it focuses on residential wiring and is indispensible for canadian diy ers it is better to get this book than the cec unless you do a lot of wiring or answer questions on the net it is updated each time the provincial codes are this book is available at all diy and hardware stores for less than c subject inspections how and what why should i get my wiring inspected most jurisdictions require that you obtain a permit and inspections of any wiring that is done amongst other more mundane bureaucratic reasons like insurance companies not liking to have to pay claims a permit and inspections provides some assurance that you your family your neighbors or subsequent owners of your home don t get killed or lose their homes one night due to a sloppy wiring job most jurisdictions have the power to order you to vacate your home or order you to tear out any wiring done without a permit california for instance is particularly nasty about this if fire starts in your home and un inspected wiring is at fault insurance companies will often refuse to pay the damage claims in general the process goes like this you apply to your local inspections office or building department for a permit you should have a sketch or detailed drawing of what you plan on doing this is a good time to ask questions on any things you re not sure of if you re doing major work they may impose special conditions on you require loading calculations and ask other questions at this point they will tell you which inspections you will need if you re installing a main panel you will need to have the panel and service connections inspected before your power utility will provide a connection this is sometimes done by the local power authority rather than the usual inspectors after installing the boxes and wiring but before the insulation walls go up you will need a rough in inspection after the walls are up and the wiring is complete you will need a final inspection subject my house doesn t meet some of these rules and regulations do i have to upgrade in general there is no requirement to upgrade older dwellings though there are some exceptions ie smoke detectors in some cases however any new work must be done according to the latest electrical code also if you do major work you may be required to upgrade certain existing portions or all of your system check with your local electrical inspector subject a word on voltages one thing where things might get a bit confusing is the different numbers people bandy about for the voltage of a circuit one person might talk about v another v or another v these are all in fact exactly the same thing in north america the utility companies are required to supply a split phase volt feed to your house this works out as two v legs additionally since there are resistive voltage drops in the house wiring it s not unreasonable to find v has dropped to v or v has dropped to v by the time the power reaches a wall outlet especially at the end of an extension cord or long circuit run for a number of reasons some historical some simple personal orneryness different people choose call them by slightly different numbers this faq has chosen to be consistent with calling them v and v except when actually saying what the measured voltage will be confusing a bit just ignore it one thing that might make this a little more understandable is that the nameplates on equipment ofen show the lower ie v instead of v value what this implies is that the device is designed to operate properly when the voltage drops that low v is not the same as v v is the voltage between phases of a phase y circuit that is v from neutral to any hot v is the voltage between phases of a phase y circuit that s v from hot to neutral in keeping with v versus v strangeness motors intended to run on v three phase are often labelled as v subject what does an electrical service look like there are logically four wires involved with supplying the main panel with power three of them will come from the utility pole and a fourth bare wire comes from elsewhere the bare wire is connected to one or more long metal bars pounded into the ground or to a wire buried in the foundation or sometimes to the water supply pipe has to be metal continuous to where the main water pipe entering the house watch out for galvanic action conductivity breaks often between copper and iron pipe this is the grounding conductor it is there to make sure that the third prong on your outlets is connected to ground this wire normally carries no current one of the other wires will be white or black with white or yellow stripes or sometimes simply black it is the neutral wire it is connected to the centre tap cec center tap in the nec of the distribution transformer supplying the power it is connected to the grounding conductor in only one place often inside the panel the neutral and ground should not be connected anywhere else otherwise weird and or dangerous things may happen furthermore there should only be one grounding system in a home some codes require more than one grounding electrode these will be connected together or connected to the neutral at a common point still one grounding system adding additional grounding electrodes connected to other portions of the house wiring is unsafe and contrary to code if you add a subpanel the ground and neutral are usually brought as separate conductors from the main panel and are not connected together in the subpanel ie still only one neutral ground connection however in some situations certain categories of separate buildings you actually do have to provide a second grounding electrode consult your inspector the other two wires will usually be black and are the hot wires they are attached to the distribution transformer as well the two black wires are degrees out of phase with each other this means if you connect something to both hot wires the voltage will be volts if you connect something to the white and either of the two blacks you will get v some panels seem to only have three wires coming into them this is either because the neutral and ground are connected together at a different point eg the meter or pole and one wire is doing dual duty as both neutral and ground or in some rare occasions the service has only one hot wire v only service subject what is a circuit inside the panel connections are made to the incoming wires these connections are then used to supply power to selected portions of the home there are three different combinations one hot one neutral and ground v circuit two hots no neutral and ground v circuit two hots neutral and ground v circuit neutral and or two v circuits with a common neutral is used for most circuits supplying receptacles and lighting within your house is usually used for supplying power to major appliances such as stoves and dryers they often have need for both v and v or for bringing several circuits from the panel box to a distribution point is usually for special v motor circuits electric heaters or air conditioners note in the us the nec frequently permits a circuit similar to be used for stoves and dryers namely that there are two hot wires and a wire that does dual duty as neutral and ground and is connected to the frame as well as providing the neutral for v purposes three prong plugs instead of four only for stoves dryers connected to the main panel when connected to most sub panels prong plugs and receptacles are required in our not so humble opinion this is crazy but the nfpa claims that this practice was re evaluated for the nec and found to be safe check your local codes or inquire as to local practice there are restrictions on when this is permissible is usually wired with three conductor wire black for hot white for neutral and bare for grounding and have one hot wire coloured red the other black a bare wire for grounding and in a white wire for neutral you will sometimes see wired with just a black white and ground wire since the white is hot in this case both the nec and cec requires that the white wire be permanently marked at the ends to indicate that it is a live wire usually done with paint nail polish or sometimes electrical tape each circuit is attached to the main wires coming into the panel through a circuit breaker or fuse there are in a few locales circuits that look like or except that they have two bare ground wires some places require this for hot tubs and the like one ground is frame ground the other attaches to the motor this may or may not be an alternative to gfci protection subject grounding versus grounded versus neutral according to the terminology in the cec and nec the grounding conductor is for the safety ground i e the green or bare wire the word neutral is reserved for the white when you have a circuit with more than one hot wire since the white wire is connected to neutral and the grounding conductor inside the panel the proper term is grounded conductor however the potential confusion between grounded conductor and grounding conductor can lead to potentially lethal mistakes you should never use the bare wire as a grounded conductor or white wire as the grounding conductor even though they are connected together in the panel but not in subpanels subpanels are fed neutral and ground separately from the main panel usually in the trade and in common usage the word neutral is used for grounded conductor this faq uses neutral simply to avoid potential confusion we recommend that you use neutral too thus the white wire is always except in some light switch applications neutral not ground subject what does a fuse or breaker do what are the differences fuses and circuit breakers are designed to interrupt the power to a circuit when the current flow exceeds safe levels for example if your toaster shorts out a fuse or breaker should trip protecting the wiring in the walls from melting as such fuses and breakers are primarily intended to protect the wiring ul or csa approval supposedly indicates that the equipment itself won t cause a fire fuses contain a narrow strip of metal which is designed to melt safely when the current exceeds the rated value thereby interrupting the power to the circuit fuses trip relatively fast which can sometimes be a problem with motors which have large startup current surges for motor circuits you can use a time delay fuse one brand is fusetron which will avoid tripping on momentary overloads a fusetron looks like a spring loaded fuse a fuse can only trip once then it must be replaced breakers are fairly complicated mechanical devices they usually consist of one spring loaded contact which is latched into position against another contact when the current flow through the device exceeds the rated value a bimetallic strip heats up and bends by bending it trips the latch and the spring pulls the contacts apart circuit breakers behave similarly to fusetrons that is they tend to take longer to trip at moderate overloads than ordinary fuses with high overloads they trip quickly breakers can be reset a finite number of times each time they trip or are thrown when the circuit is in use some arcing takes place which damages the contacts thus breakers should not be used in place of switches unless they are specially listed for the purpose neither fuses nor breakers limit the current per se a dead short on a circuit can cause hundreds or sometimes even thousands of amperes to flow for a short period of time which can often cause severe damage subject breakers can t i use fuses statistics show that fuse panels have a significantly higher risk of causing a fire than breaker panels this is usually due to the fuse being loosely screwed in or the contacts corroding and heating up over time or the wrong size fuse being installed or the proverbial replace the fuse with a penny trick since breakers are more permanently installed and have better connection mechanisms the risk of fire is considerably less fuses are prone to explode under extremely high overload when a fuse explodes the metallic vapor cloud becomes a conducting path result from complete meltdown of the electrical panel melted service wiring through fires in the electrical distribution transformer and having your house burn down breakers don t do this many jurisdictions particularly in canada no longer permit fuse panels in new installations the nec does permit new fuse panels in some rare circumstances requiring the special inserts to key the fuseholder to specific size fuses some devices notably certain large air conditioners require fuse protection in addition to the breaker at the panel the fuse is there to protect the motor windings from overload check the labeling on the unit this is usually only on large permanently installed motors the installation instructions will tell you if you need one subject what size wire should i use for a amp circuit use gauge wire for a amp circuit you can use gauge wire in most locales for a long run though you should use the next larger size wire to avoid voltage drops gauge is only slightly more expensive than gauge though it s stiffer and harder to work with here s a quick table for normal situations go up a size for more than foot runs when the cable is in conduit or ganged with other wires in a place where they can t dissipate heat easily gauge amps we don t list bigger sizes because it starts getting very dependent on the application and precise wire type subject where do these numbers come from there are two considerations voltage drop and heat buildup the smaller the wire is the higher the resistance is when the resistance is higher the wire heats up more and there is more voltage drop in the wiring the former is why you need higher temperature insulation and or bigger wires for use in conduit the latter is why you should use larger wire for long runs neither effect is very significant over very short distances there are some very specific exceptions where use of smaller wire is allowed the obvious one is the line cord on most lamps don t try this unless you re certain that your use fits one of those exceptions you can never go wrong by using larger wire subject what does mean this is used to describe the size and quantity of conductors in a cable the first number specifies the gauge the second the number of current carrying conductors in the wire but remember there s usually an extra ground wire means gauge two insulated current carrying wires plus bare ground wire usually has a black white and bare ground wire sometimes the white is red instead for v circuits without neutral in the latter case the sheath is usually red too wire usually has a black red white and bare ground wire usually carrying v with neutral subject what is a wirenut marrette marr connector how are they used a wire nut is a cone shaped threaded plastic thingummy that s used to connect wires together marrette or marr connector are trade names you ll usually use a lot of them in diy wiring in essence you strip the end of the wires about an inch twist them together then twist the wirenut on though some wirenuts advertise that you don t need to twist the wire do it anyways it s more mechanically and electrically secure there are many different sizes of wire nut you should check that the wire nut you re using is the correct size for the quantity and sizes of wire you re connecting together don t just gimble the wires together with a pair of pliers or your fingers use a pair of blunt nose linesman pliers and carefully twist the wires tightly and neatly sometimes it s a good idea to trim the resulting end to make sure it goes in the wirenut properly some people wrap the open end of the wirenut with electrical tape this is probably not a good idea the inspector may tear it off during an inspection it s usually done because a bit of bare wire is exposed outside the wire nut instead of taping it the connection should be redone subject what is a gfi gfci a gfci is a ground fault circuit interrupter it measures the current current flowing through the hot wire and the neutral wire if they differ by more than a few milliamps the presumption is that current is leaking to ground via some other path this may be because of a short circuit to the chassis of an appliance or to the ground lead or through a person any of these situations is hazardous so the gfci trips breaking the circuit gfcis do not protect against all kinds of electric shocks if for example you simultaneously touched the hot and neutral leads of a circuit and no part of you was grounded a gfci wouldn t help all of the current that passed from the hot lead into you would return via the neutral lead keeping the gfci happy the two pairs of connections on a gfci outlet are not symmetric one is labeled load the other line the incoming power feed must be connected to the line side or the outlet will not be protected the load side can be used to protect all devices downstream from it thus a whole string of outlets can be covered by a single gfci outlet subject where should gfcis be used the nec mandates gfcis for v a or a single phase outlets in bathrooms kitchens within of the sink garages unfinished basements or crawl spaces outdoors near a pool or just about anywhere else where you re likely to encounter water or dampness there are exceptions for inaccessible outlets those dedicated to appliances occupying fixed space typically refrigerators and freezers and for sump pumps and laundry appliances the cec does not mandate as many gfcis in particular there is no requirement to protect kitchen outlets or most garage or basement outlets basement outlets must be protected if you have a dirt floor garage outlets if they re near the door to outside bathrooms and most exterior outlets must have gfcis even if you are not required to have gfci protection you may want to consider installing it anyway unless you need a gfci breaker see below the cost is low in the u s gfci outlets can cost as little as us costs are a bit higher in canada c evaluate your own risk factors does your finished basement ever get wet do you have small children do you use your garage outlets to power outdoor tools does water or melted snow ever puddle inside your garage subject where shouldn t i use a gfci gfcis are generally not used on circuits that a don t pose a safety risk and b are used to power equipment that must run unattended for long periods of time refrigerators freezers and sump pumps are good examples the rationale is that gfcis are sometimes prone to nuisance trips some people claim that the inductive delay in motor windings can cause a momentary current imbalance tripping the gfci note though that most gfci trips are real if you re getting a lot of trips for no apparent reason you d be well advised to check your wiring before deciding that the gfci is broken or useless subject what is the difference between a gfci outlet and a gfci breaker for most situations you can use either a gfci outlet as the first device on the circuit or you can install a breaker with a built in gfci the former is generally preferred since gfci breakers are quite expensive for example an ordinary ge breaker costs us the gfci model costs us there is one major exception if you need to protect a multi wire branch circuit two or more circuits sharing a common neutral wire such as a canadian style kitchen circuit you ll need a multi pole gfci breaker unfortunately these are expensive the cost can range into the hundreds of dollars depending on what brand of panel box you have but if you must protect such a circuit say for a pool heater you have no choice one more caveat gfci outlets are bulky you may want to use an oversize box when installing them on second thought use large actually deep boxes everywhere you ll thank yourself for it incidentally if you re installing a gfci to ensure that one specific outlet is protected such as a bathroom you don t really have to go to all of the trouble to find the first outlet in the circuit you could simply find the first outlet in the bathroom and not gfci anything upstream of it but protecting the whole circuit is preferred when you install a gfci it s a good idea to use the little ground fault protected stickers that come with it and mark the outlets downstream of the gfci you can figure out which outlets are downstream simply by tripping the gfci with the test button and see which outlets are dead subject what s the purpose of the ground prong on an outlet then apart from their use in electronics which we won t comment on and for certain fluorescent lights they won t turn on without a good ground connection they re intended to guard against insulation failures within the device generally the case of the appliance is connected to the ground lead if there s an insulation failure that shorts the hot lead to the case the ground lead conducts the electricity away safely and possibly trips the circuit breaker in the process if the case is not grounded and such a short occurs the case is live and if you touch it while you re grounded you ll get zapped of course if the circuit is gfci protected it will be a very tiny zap which is why you can use gfcis to replace ungrounded outlets both nec and cec there are some appliances that should never be grounded in particular that applies to toasters and anything else with exposed conductors consider if you touch the heating electrode in a toaster and you re not grounded nothing will happen if you re slightly grounded you ll get a small shock the resistance will be too high but if the case were grounded and you were holding it you d be the perfect path to ground subject why is one prong wider than the other polarization nowadays many two prong devices have one prong wider than the other this is so that the device could rely not guaranteed on one specific wire being neutral and the other hot this is particularly advantageous in light fixtures where the the shell should neutral safety or other devices which want to have an approximate ground reference ie some radios most prong extension cords have wide prongs too this requires that you wire your outlets and plugs the right way around you want the wide prong to be neutral and the narrow one hot most outlets have a darker metal for the hot screw and lighter coloured screw for the neutral if not you can usually figure out which is which by which prong the terminating screw connects to subject what kind of outlets do i need in a kitchen the nec requires at least two amp small appliance circuits for kitchens the cec requires split duplex receptacles outlets must be installed such that no point is more than nec mm cec from an outlet every counter wider than nec or mm cec must have at least one outlet the circuit these outlets are on may not feed any outlets except in the kitchen pantry or dining room furthermore these circuits are in addition to any required for refrigerators stoves microwaves lighting etc non dedicated outlets within of a sink must be protected by a gfci nec only split duplex receptacles are fed with a v circuit the tab is broken on the hot side of the outlet and one hot goes to the upper outlet and the other hot goes to the lower outlet the neutral connects to both outlets through one screw when carrying through to another outlet the neutral must be pigtailed such that removing the outlet or having the neutral connection fall off doesn t cause the neutral to disconnect from downstream outlets subject where must outlets and switches be in bathrooms there must be at least one outlet in each bathroom adjacent to the sink in addition to any outlet that may be incorporated in the light fixture all such outlets must be gfci protected subject what is romex nm nmd what is bx when should i use each romex is a brand name for a type of plastic insulated wire sometimes called non metallic sheath the formal name is nm this is suitable for use in dry protected areas ie inside stud walls on the sides of joists etc that are not subject to mechanical damage or excessive heat most newer homes are wired almost exclusively with nm wire there are several different categories of nm cable bx cable technically known as armored cable or ac has a flexible aluminum or steel sheath over the conductors and is fairly resistant to damage teck cable is ac with an additional external thermoplastic sheath protection for cable in concealed locations where nm or ac cable is run through studs joists or similar wooden members the outer surface of the cable must be kept at least mm cec nec from the edges of the wooden members or the cable should be protected from mechanical injury this latter protection can take the form of metal plates such as spare outlet box ends or conduit note inspector permitted practise in canada suggests that armored cable or flexible conduit can be used as the mechanical protection but this is technically illegal additional protection recommendations these are rules in the canadian codes they are reasonable answers to the vague references to exposed to mechanical damage in both the nec and cec nm cable should be protected against mechanical damage where it passes through floors or on the surface of walls in exposed locations under feet from the floor ie use ac instead flexible conduit wooden guards etc where cable is suspended as in connections to furnaces or water heaters the wire should be protected canadian practise is usually to install a junction or outlet box on the wall and use a short length of ac cable or nm cable in flexible conduit to jump to the appliance stapling nm to a piece of lumber is also sometimes used where nm cable is run in close proximity to heating ducts or pipe heat transfer should be minimized by means of a mm air space or suitable insulation material a wad of fiberglass nm cable shall be supported within mm of every box or fitting and at intervals of no more than m holes in joists or studs are considered supports some slack in the cable should be provided adjacent to each box while fishing cable is technically in violation it is permitted where proper support is impractical conductor nm cable should never be stapled on edge knight also insists on only one cable per staple referring to the workmanship clause but this seems more honoured in the breach cable should never be buried in plaster cement or similar finish cable should be protected where it runs behind baseboards cable may not be run on the upper edge of ceiling joists or the lower edges of rafters where the headroom is more than m whenever bx cable is terminated at a box with a clamp small plastic bushings must be inserted in the end of the cable to prevent the clamps forcing the sharp ends of the armor through the insulation bx is sometimes a good idea in a work shop unless covered by solid wall coverings in places where damage is more likely like on the back wall of a garage you may be required to use conduit a ul or csa approved metal pipe you use various types of fittings to join the pipe or provide entrance exit for the wire service entrances frequently use a plastic conduit in damp places eg buried wiring to outdoor lighting you will need special wire eg cec nmw nec uf nmw looks like very heavy duty nmd you will usually need short lengths of conduit where the wire enters exits the ground see underground wiring section thermoplastic sheath wire such as nm nmw etc should not be exposed to direct sunlight unless explicitly approved for that purpose many electrical codes do not permit the routing of wire through furnace ducts including cold air return plenums constructed by metal sheeting enclosing joist spaces the reason for this is that if there s a fire the ducting will spread toxic gasses from burning insulation very rapidly through the building teflon insulated wire is permitted in plenums in many areas canada appears to use similar wire designations to the us except that canadian wire designations usually include the temperature rating in celsius eg ac versus ac in the us nm b is degrees celcius note local codes vary this is one of the items that changes most often eg chicago codes require conduit everywhere there are very different requirements for mobile homes check your local codes especially if you re doing anything that s the slightest out of the ordinary wire selection table incomplete the real tables are enormous uncommon wire types or applications omitted condition type cec nec exposed concealed dry plastic nmd nm armor ac ac teck exposed concealed damp plastic nmd nmc armor acwu teck exposed concealed wet plastic nmwu armor acwu teck exposed to weather plastic nmwu tw etc armor teck direct earth burial plastic nmwu uf service entrance rwu twu armor ra teck acwu nmwu not for service entrance subject should i use plastic or metal boxes the nec permits use of plastic boxes with non metallic cable only the reasoning is simple with armored cable the box itself provides ground conductor continuity u s plastic boxes don t use metal cable clamps the cec is slightly different the cec never permits cable armor as a grounding conductor however you must still provide ground continuity for metallic sheath the cec also requires grounding of any metal cable clamps on plastic boxes the advantage of plastic boxes is comparatively minor even for non metallic sheathed cable you can avoid making one ground connection and they sometimes cost a little less on the other hand plastic boxes are more vulnerable to impacts for exposed or shop wiring metal boxes are probably better subject junction box positioning a junction box is a box used only for connecting wires together junction boxes must be located in such a way that they re accessible later ie not buried under plaster excessive use of junction boxes is often a sign of sloppy installation and inspectors may get nasty subject can i install a replacement light fixture in general one can replace fixtures freely subject to a few caveats first of course one should check the amperage rating of the circuit if your heart is set on installing half a dozen watt floodlights you may need to run a new wire back to the panel box but there are some more subtle constraints as well for example older house wiring doesn t have high temperature insulation the excess heat generated by a ceiling mounted lamp can and will cause the insulation to deteriorate and crack with obvious bad results some newer fixtures are specifically marked for high temperature wire only you may find in fact that your ceiling wiring already has this problem in which case replacing any devices is a real adventure other concerns include providing a suitable ground for some fluorescent fixtures and making sure that the ceiling box and its mounting are strong enough to support the weight of a heavy chandelier or ceiling fan you may need to install a new box specifically listed for this purpose a x across the ceiling joists makes a good support metal brackets are also available that can be fished into ceilings thru the junction box hole and mounted between the joists there are special rules for recessed light fixtures such as pot lamps or heat lamps when these are installed in insulated ceilings they can present a very substantial fire hazard the cec provides for the installation of pot lamps in insulated ceilings provided that the fixture is boxed in a coffin usually x x made by making a pair of joists high and covering with plywood that doesn t have any insulation yes that s feet long nec rules are somewhat less stringent they require at least clearance between the fixture and any sort of thermal insulation the rules also say that one should not obstruct free air movement which means that a cec style coffin might be worthwhile presumably that s up to the local inspector the cec doesn t actually mandate the coffin per se this seems to be an inspector requirement to make absolutely certain that the fixture can t get accidentally buried in insulation ie if you have insulation blown in later there are now fixtures that contain integral thermal cutouts and fairly large cases that can be buried directly in insulation they are usually limited to watt bulbs and are unfortunately somewhat more expensive than the older types before you use them you should ensure that they have explicit ul or csa approval for such uses follow the installation instructions carefully the prescribed location for the sensor can vary there does not yet appear to be a heat lamp fixture that is approved for use in insulation the coffin appears the only legal approach subject what does it mean when the lights brighten when a motor starts this usually means that the neutral wire in the panel is loose depending on the load balance one hot wire may end up being more than v and the other less than v with respect to ground this is a very hazardous situation it can destroy your electronic equipment possibly start fires and in some situations electrocute you ie some us jurisdictions require the stove frame connected to neutral if this happens contact your electrical authority immediately and have them come and check out the problem note a brief second brightening is sometimes normal with lighting and motors on the same v with neutral circuit a loose main panel neutral will usually show increased brightness far longer than one second in case of doubt get help subject what is phase power should i use it can i get it in my house three phase power has three hot wires degrees out of phase with each other these are usually used for large motors because it is more efficient provides a bit more starting torque and because the motors are simpler and hence cheaper you re most likely to encounter a phase circuit that shows volts between any hot and ground and volts between any two hots the latter shows the difference between a normal v v common neutral circuit which is volts between the two hots there are phase circuits with different voltages bringing in a phase feed to your house is usually ridiculously expensive or impossible if the equipment you want to run has a standard motor mount it is much cheaper to buy a new v or v motor for it in some cases it is possible to run phase equipment on ordinary power if you have a capacitor start unit or use a larger motor as a auto generator these are tricky but are a good solution if the motor is non standard size or too expensive or too big to replace the taunton press book the small shop has an article on how to do this if you must note that you lose any possible electrical efficiency by using such a converter the laws of thermodynamics guarantee that subject is it better to run motors at or theoretically it doesn t make any difference however there is a difference is the amount of power lost in the supply wiring all things being equal a v motor will lose times less power in the house wiring than a v motor this also means that the startup surge loss will be less and the motor will get to speed quicker and in some circumstances the smaller power loss will lead to longer motor life this is usually irrelevant unless the supply wires are more than feet long subject what is this nonsense about hp on v a circuits it is a universal physical law that hp is equal to watts given heating loss power factor and other inefficiencies it is usually best to consider hp is going to need watts a v a circuit can only deliver watts to a motor so it cannot possibly be more than approximately hp given rational efficiency factors hp is more like it some equipment manufacturers sears in particular most router manufacturers in general advertise a hp rating that is far in excess of what is possible they are giving you a stall horsepower or similar that means the power is measured when the motor is just about to stop turning because of the load what they don t mention is that if you kept it in that condition for more than a few seconds hopefully your breaker will trip otherwise the motor will melt it s drawing far more current than it can continuously when comparing motors compare the continuous horsepower this should be on the motor nameplate if you can t find that figure check the amperage rating which is always present subject how do i convert two prong receptacles to three prong older homes frequently have two prong receptacles instead of the more modern three these receptacles have no safety ground and the cabling usually has no ground wire neither the nec or cec permits installing new prong receptacles anymore there are several different approaches to solving this if the wiring is done through conduit or bx and the conduit is continuous back to the panel you can connect the third prong of a new receptacle to the receptacle box nec mainly cec frowns on this practise if there is a copper cold water pipe going nearby and it s continuous to the main house ground point you can run a conductor to it from the third prong run a ground conductor back to the main panel easiest install a gfci receptacle the ground lug should not be connected to anything but the gfci protection itself will serve instead the gfci will also protect downstream possibly also two prong outlets if you do this to protect downstream outlets the grounds must not be connected together since it wouldn t be connected to a real ground a wiring fault could energize the cases of prong devices connected to other outlets be sure though that there aren t indirect ground plug connections such as via the sheath on bx cable the cec permits you to replace a two prong receptacle with a three prong if you fill the u ground with a non conducting goop like caulking compound this is not permitted in the nec subject are you sure about gfcis and ungrounded outlets should the test button work we re sure about what the nec and cec say remember though that your local codes may vary as for the test button there s a resistor connecting the load side of the hot wire to the line side of the neutral wire when you press the test button current through this resistor shows up as an imbalance and trips the gfci this is a simple passive and reliable test and doesn t require a real ground to work if your gfci does not trip when you press the test button it is very probably defective or miswired again if the test button doesn t work something s broken and potentially dangerous the problem should be corrected immediately the instructions that come with some gfcis specify that the ground wire must be connected we do not know why they say this the causes may be as mundane as an old instruction sheet or with the formalities of ul or csa listing perhaps the device was never tested without the ground wire being connected on the other hand ul or csa approval should only have been granted if the device behaves properly in all listed applications including ungrounded outlet replacement one of us called leviton their gfcis are labeled for installation on grounded circuits only the technician was surprised to see that he agreed that the nec does not require it and promised to investigate subject how should i wire my shop as with any other kind of wiring you need enough power for all devices that will be on simultaneously the code specifies that you should stay under of the nominal capacity of the circuit for typical home shop use this means one circuit for the major power tools and possibly one for a dust collector or shop vac use at least gauge wire many power tools have big motors with a big start up surge if you can use amp breakers nec though cec requires standard a receptacles which means you d have to replug all your equipment lights should either be on a circuit of their own and not shared with circuits in the rest of the house or be on at least two separate circuits the idea is that you want to avoid a situation where a blade is still spinning at several thousand rpm while you re groping in the dark for the off switch do install lots of outlets it s easier to install them in the beginning when you don t have to cut into an existing cable it s useful if at least two circuits are accessible at each point so you can run a shop vac or a compressor at the same time as the tool you really want but use metal boxes and plates and maybe even metal sheathed cable you may have objects flying around at high speeds if something goes a bit wrong note that some jurisdictions have a no horizontal wiring rule in workshops or other unfinished areas that are used for working what this means is that all wiring must be run along structural members ie stapled to studs other possible shop circuits include heater circuits v circuits for some large tools and air compressor circuits don t overload circuits and don t use extension cords if you can help it unless they re rated for high currents a coiled extension cord is not as safe as a straight length of wire of the same gauge also the insulation won t withstand as much heat and heat dissipation is the critical issue if your shop is located at some remove from your main panel you should probably install a subpanel and derive your shop wiring from it if you have young children you may want to equip this panel with a cut off switch and possibly a lock if you want to install individual switches to safe particular circuits make sure you get ones rated high enough for example ordinary light switches are not safely able to handle the start up surge generated by a table saw buy horsepower rated switches instead finally note that most home shops are in garages or unfinished basements hence the nec requirements for gfcis apply and even if you know that you d never use one of your shop outlets to run a lawn mower the next owner of your house might have a different idea note fine woodworking magazine often carries articles on shop wiring april is one place to start subject underground wiring you will need to prepare a trench to specifications use special wire protect the wire with conduit or special plastic tubing and possibly lumber don t use creosoted lumber it rots thermoplastic insulation and acts as a catalyst in the corrosion of lead the transition from in house to underground wire is generally via conduit all outdoor boxes must be specifically listed for the purpose and contain the appropriate gaskets fittings etc if the location of the box is subject to immersion in water a more serious style of water proof box is needed and of course don t forget the gfcis the required depths and other details vary from jurisdiction to jurisdiction so we suggest you consult your inspector about your specific situation a hint buy a roll of bright yellow tape that says buried power line and bury it a few inches above where the wire has been placed subject aluminum wiring during the s aluminum instead of copper wiring became quite popular and was extensively used since that time aluminum wiring has been implicated in a number of house fires and most jurisdictions no longer permit it in new installations we recommend even if you re allowed to that do not use it for new wiring but don t panic if your house has aluminum wiring aluminum wiring when properly installed can be just as safe as copper aluminum wiring is however very unforgiving of improper installation we will cover a bit of the theory behind potential problems and what you can do to make your wiring safe the main problem with aluminum wiring is a phenomenon known as cold creep when aluminum wiring warms up it expands when it cools down it contracts unlike copper when aluminum goes through a number of warm cool cycles it loses a bit of tightness each time to make the problem worse aluminum oxidises or corrodes when in contact with certain types of metal so the resistance of the connection goes up which causes it to heat up and corrode oxidize still more eventually the wire may start getting very hot melt the insulation or fixture it s attached to and possibly even cause a fire since people usually encounter aluminum wiring when they move into a house built during the s we will cover basic points of safe aluminum wiring we suggest that if you re considering purchasing a home with aluminum wiring or have discovered it later that you hire a licensed electrician or inspector to check over the wiring for the following things fixtures eg outlets and switches directly attached to aluminum wiring should be rated for it the device will be stamped with al cu or co alr the latter supersedes the former but both are safe these fixtures are somewhat more expensive than the ordinary ones wires should be properly connected at least way around the screw in a clockwise direction connections should be tight while repeated tightening of the screws can make the problem worse during the inspection it would pay off to snug up each connection note that aluminum wiring is still often used for the main service entrance cable it should be inspected push in terminals are an extreme hazard with aluminum wire any connections using push in terminals should be redone with the proper screw connections immediately there should be no signs of overheating darkened connections melted insulation or baked fixtures any such damage should be repaired connections between aluminum and copper wire need to be handled specially current canadian codes require that the wire nut used must be specially marked for connecting aluminum to copper the nec requires that the wire be connected together using special crimp devices with an anti oxidant grease the tools and materials for the latter are quite expensive not practical to do it yourself unless you can rent the tool any non rated receptacle can be connected to aluminum wiring by means of a short copper pigtail see above shows reasonable workmanship neat wiring properly stripped not nicked wire etc if when considering purchasing a home an inspection of the wiring shows no problems or only one or two we believe that you can consider the wiring safe if there are signs of problems in many places we suggest you look elsewhere if the wrong receptacles are used you can replace them with the proper type or use pigtails having this professionally done can range from to per receptacle switch you can do this yourself too subject i m buying a house what should i do congratulations but it s generally a good idea to hire an inspector to look through the house for hidden gotchas not just for wiring but plumbing and structural as well if an inspection of the wiring shows no problems or only one or two minor ones we believe that you can consider the wiring safe after any minor problems are fixed if there are signs of problems in many places we suggest you look elsewhere here s some hints on what to look for obvious non code wiring can include zip cord wiring either concealed or nailed to walls hot wiring on the identified neutral conductor without proper marking ungrounded grounding outlets except when downstream of a gfci splices hanging in mid air other than proper knob and tube switched neutrals unsecured romex swinging about like grapevines certain wiring practises that are actually to code or were at one time sometimes reveal diy wiring that may have hidden violations switches that seem to control nothing abandoned perhaps not properly terminated wiring a wall switch that shuts off a group of lights that are separately controlled by other wall switches except when it s really convenient switches and outlets in bizarre locations great numbers of junction boxes without outlets or lamps junction boxes with great numbers of wires going into them wiring that passes through a closet instead of a wall or ceiling backwrapped grounding wires subject what is this weird stuff old style wiring in the years since edison invented electricity several different wiring styles have come and gone when you buy an older home you may encounter some of this stuff this section describes the old methods and some of their idiosyncrasies the oldest wiring system you re likely to encounter is called knob and tube k t it is made up of individual conductors with a cloth insulation the wires are run along side structural members eg joists or studs using ceramic stand offs knobs wire is run through structural members using ceramic tubes connections were made by twisting the wire together soldering and wrapping with tape since the hot and neutral were run separately the wiring tends to be rather confusing a neutral often runs down the centre of each room with taps off to each fixture the hot wire tended to run from one fixture to the next in some cases k t isn t colour coded so the neutral is often the same colour as the hot wires you ll see k t in homes built as late as the s comments on k t the people installing k t were pretty paranoid about electricity so the workmanship tends to be pretty good the wire insulation and insulators tend to stand up very well most k t i ve seen for example is in quite good condition no grounding grounding is usually difficult to install boxes are small receptacle replacement particularly with gfci can be difficult no bushing on boxes either so wiring changes need special attention to box entry sometimes the neutral isn t balanced very well between separately hot circuits so it is sometimes possible to overload the neutral without exceeding the fusing on any circuit building code does not permit insulation in walls that contain k t connection to existing k t from new circuits can be tricky consult your inspector modern wiring practise requires considerably more outlets to be installed than k t systems did since k t tends to be in pretty decent condition it generally isn t necessary to replace it simply because it s k t what you should watch out for is renovations that have interfered with it and be cautious about circuit loading in many cases it s perfectly reasonable to leave existing k t alone and add new fixtures on new circuits using modern techniques after k t they invented multi conductor cable the first type you will see is roughly a cloth and varnish insulation it looks much like the romex cable of the last decade or two this stuff was used in the s and s again no grounding conductor it was installed much like modern wiring its major drawback is that this type of insulation embrittles we ve seen whole systems where the insulation would fracture and fall off at a touch bx cable of the same vintage has similar problems this stuff is very fragile and becomes rather hazardous if the wires become bare this wiring should be left untouched as much as possible whenever an opportunity arises replace it a simple receptacle or switch replacement can turn into a several hour long frustrating fight with electrical tape or heat shrink tubing after this wiring technique the more modern romex was invented it s almost a asphalt impregnated cloth often a bit sticky this stuff stands up reasonably well and doesn t present a hazard and is reasonably easy to work with it does not need to be replaced it should be considered as safe as the modern stuff thermoplastic insulation wire just don t abuse it too much subject where do i buy stuff try to find a proper electrical supply outlet near you their prices will often be considerably better than chain hardware stores or diy centres have better quality materials have wider variety including the odd stuff and have people behind the counter that know what you re talking about cultivate friendly knowledgeable sales people they ll give you much valuable information chris lewis clewis ferret ocunix on ca phone canada psroff info psroff request ferret ocunix on ca ferret list ferret request ferret ocunix on ca
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re what do nuclear site s cooling towers do in article qlg o d q sequoia ccsd uts edu au swalker uts edu au s s walker man writes i really don t know where to post this question so i figured that this board would be most appropriate i was wondering about those massive concrete cylinders that are ever present at nuclear poer sites they look like cylinders that have been pinched in the middle does anybody know what the actual purpose of those things are i hear that they re called cooling towers but what the heck do they cool water nuclear stations don t generate electricity directly from the reactor they use the reactor to generate heat the heat is then used to heat water just as in a conventional oil or coal station and the resultant steam drives the turbines the cooling towers are used to cool the steam and recondense it into water to continue the cycle steve steve mckinty sun microsystems icnc meylan france email smckinty france sun com bix smckinty
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re trace size for a amp supply r g keen rg futserv austin ibm com wrote a quick and dirty way to get higher current carrying capacity on pc board traces for one or few of a kind boards is to strip some romex house wiring cable to bare copper form the bare copper to follow the trace and solder it down and if it s not quick and dirty you can get bus bars that are stamped out with leads that insert in the pc board mark zenier markz ssc wa com markz ssc com
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re looking for a good spice book in article canright convex com canright convex com robert canright writes you might try computer aided circuit analysis using spice by walter banzhaf at bookstores paperback lots of examples dr banzhaf is a teacher is there another book i have this one and don t find it helpfull in learning spice it would make a good reference book but i found it lacking for learning spice are there any others craig you took the bull by the horns craig williamson and stepped in something good craig williamson columbiasc ncr com balki bartokomas craig toontown columbiasc ncr com home perfect strangers
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re how do di boxes work in article lancer apr oconnor wpi edu lancer oconnor wpi edu stephe lewis foskett writes i m doing sound for a couple of bands around here and we need direct input boxes for the keyboards these are the little boxes that take a line level out of the keyboard and transform it into low z for the run to the mixer sadly they cost like or more each and i m going to need like or of them i looked inside one belonging to another band and it looks like just a transformer does anyone have any plans for building them perhaps in anderton s electronic projects for musicians book which i am having a hell of a time tracking down an easy way to solve the problem is to use two op amps to form the balanced low z output but this solution does not provide any galvanic isolation between keyboard or whatever plugged and mixer if no tight requiremets are demanded and some hum snap crackle and pop sounds formed by ground loops can be tolerated the op amp solution is just what you are looking for it is cheap somewhat di box not sure but craig anderton did introduce one di box project in guitar player mag years ago transformerless thanks a lot hope this helps email if more details wanted lancer wpi wpi edu modimidofrsaso mein kopf ist ein labyrinth mein leben ist ein minenfeld heikki paananen heke stekt oulu fi the university of oulu department of electrical engineering just a student finland home is where the heart lies but if the heart lies where is home fish
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re how do di boxes work lancer oconnor wpi edu stephe lewis foskett writes i m doing sound for a couple of bands around here and we need direct input boxes for the keyboards these are the little boxes that take a line level out of the keyboard and transform it into low z for the run to the mixer sadly they cost like or more each and i m going this is indeed one function but more sophisticated ones do level control and ground lift separating the keyboard and mixer earths aswell to need like or of them i looked inside one belonging to another band and it looks like just a transformer does anyone have simple ones are just that a transformer a decent quality audio trans former will cost most of that they are wired thus hot hot input from balanced out to mixer keyboard cold gnd gnd the ground lift switch disconnects the gnd line from the mixer the transformer ratio depends on the precise application but around turns ratio may be a good place to start christopher christopher hicks paradise is a linear gaussian world cmh uk ac cam eng also reported to taste hot and sweaty
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re microphone pre amp low noise phantom powered davidj rahul net david josephson writes in c jjj tf cmcl nyu edu ali cns nyu edu alan macaluso writes i m looking to build a microphone preamp that has very good low noise characteristics large clean gain and incorportates phantom power volts dc for a pzm microphone i m leaning towards a good low cost instrumentation amplifier to maintain the balanced input from the microphone for its good cmrr internal compensation and because i can use a minimal of parts does anyone out there have any experience suggestions advice etc that they d like to pass on i d greatly appreciate it without doing anything really tricky the best i ve seen is the burr brown ina their databook shows a good application of this chip as a phantom power mic pre i ve had very good results from the ssm from pmi part of analogue devices they have also now introduced the ssm which looks good on paper but which i haven t tried yet christopher christopher hicks paradise is a linear gaussian world cmh uk ac cam eng also reported to taste hot and sweaty
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dsp hi is there somebody using a dsp from motorola i am searching for programms concerning audio effects i built a channel mixer adc dsp for audio signals i built some digital filters and echos but now i want to include some effects like harmonic equalizer or chorus the problem is i dont know how these effects work so i cant write a programm so if someone has programms or just knows how such effects work please contact me in the newsgroup or via e mail also if there are books about this problem thanks in advance dwo
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re cable tvi interference in article qevrf t hpscit sc hp com writes as is typical nowadaze you will probably have to do somebody else s job for them although this shouldn t be needed you might take a few minutes to wander around the neighborhood with an ht sniffing for cable leakage on your freq after shutting down your system for a while if you are fortunate enough to the find the hole call the cable company and get the highest link in the chain of command you can explain the problem whose job it really is to maintain their equipment and how much of a nice guy you are to have tracked down their problem for them you may have been lucky and made a new contact that could be helpful in the future you should always try the honey approach before bringing out the jack nicholson impressions this has worked for me in the past with the power company when tring to find loose noisy high voltage lines hardware only once did i have to tell them i was narrowing the problem down to a specific pole by bumping a whole line of poles with my car got em out there that night and they didn t have to meet jack as a disclaimer their method for finding loose hardware was usually whacking the poles with a huge sledgehammer after their high tech arc finding scope couldn t find the problem bill wb rotten zucchini garden here in switzerland the situation is exactly the same the cable tv companies even tried to stop amateur radio in switzerland in the beginning of cable tv they seem to be too stupid to know anything about international frequency conferences or so even today they use the cheapest possible coax running into problems they can t solve anymore as bill noted the only way is to look for a solution with the neighbours before calling for the cable tv guys or the fcc the chance to find neighbours with some sense for reason is by far bigger than with these people especially the first ones as anywhere in an administration people don t like if you tell them to work for the money they get the problem is that radio amateurs don t have the power to put trough their rights in all cases so let s hope they start soon with optical fibers and get out of our freqencies cheers robert hb nby robert ganter universitaet basel i am a fan institut fuer informatik of my plan basel switzerland ganter ifi unibas ch amateurradio hb nby packet hb nby hb eas che eu
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band equalizer i was wondering if anyone out there in net land knew of a simple way to make a band equalizer single channel i need it to accept line inputs tape deck cd player etc and output to the same so input impedance should equal output impedance also since i am driving a line i would need volt p p output final requirement is that i can either control it digitally or control it easily or with few resistors finally if anyone knows of any filter or equalizer chips that might be useful please let me know i have seen a couple of them from national and maxim thanks in advance martin
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re adcom cheap products in article c k bok world std com rogerw world std com roger a williams wrote mdonahue amiganet chi il us mike donahue writes i do not know much about adcom mobil audio products but i do know for a fact that adcom does not make its own high end home audio equptment and that of it comes directly out of tiawan like most high volume manufacturers adcom has most of its pc boards assembled off shore in their case mostly in the far east final assembly and testing are done in east brunswick and of course you older folks on the net will remember way back when adcom got its rave reviews and kudos ca or so their amp and preamp were not only designed here but built here in the usa then they went to mexico and then to taiwan right after their sales skyrocketed because of their stereopile review if you have units that old look for made in stickers on your unit
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receiver system dear netters i want to send emg signals from a running person to a computer each signal is khz wide and there is up to of them on each running person the signal is only to be sent over a few hundred meters it seems to me that the frequency intended for this use is about mhz and about mhz to make the transmitters as light as possible i suppose it will be best the to send the signals in an analog form as this application is rather specialized i do not expect to be able to buy the exact transmitter units i need on the other hand i imagine that i can buy the receiver somewhere i need a multichannel up to channels receiver or complete receivers in some rack system where one can add as many receivers as needed in the particular case do anybody know if there is existing such receiver system on the market baldur rsp is tf bp please respond by email rather than nn
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re telephone on hook off hok ok circuit in article ptolq p e werple apana org au petert zikzak apana org au peter t writes since an on hook line is aprox v and off hook it usually drops below v how about an led in series with a zener say around v on hook led on off hook led off would this work if anyone tries tried it please let me know not recommended your circuit would take too much current when telephone is on hook telephone company does not like it tomi engdahl hut fi lowery s law then niksula hut fi if it jams force it if it breaks it needed replacing anyway this text is provided as is without any express or implied warranty
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re adcom cheap products i want to upgrade my system and was thinking of buying adcom seperates i have heard from alot of people though that adcom sounds great but that the components are made cheaply and therefore won t last very long the time estimates i ve heard are like only or years is this true i own the adcom w power amp as far as i m concerned there s no amp which can touch it at the price range the build quality is very impressive and is far superior to other amps in the price range the whole amplifier is extremely solid with massive heat sinks and very solid casing if you open the amp up there are only very good quality components in and the amp seems to be designed extremely well perfect symmetry for both channels and two transformers one for each channel the binding posts on the back of the amplifier are virtually the same as those on the classe model ie very good i was also sceptical about the amps being built in the far east or where ever but if you look in the amp and see what components they use and how it was designed you can easily see why the amplifiers sound so brilliant i cannot see why people say the amplifier won t last not with those quality components inside sure the amp runs very fairly hot but that s how you get an amp to sound incredibly good my last point i recently auditioned the adcom preamp something like the or something it was two years old and it still sounded like new if you build an amplifier decently like the adcom s they will sound brilliant and last a long time period just my thoughts but then i do own one of adcom s amps alan webber webb itu sun ac za webb itu sun ac za the path you tread is narrow and the drop is sheer and very high the ravens all are watching from a vantage point near by apprehension creeping like a choo train up your spine will the tightrope reach the end will the final couplet rhyme
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high level language compilers for ucontrollers howdy chaps has anybody got any pointers to good c pascal etc compilers for microcontrollers shareware or otherwise my specific need is for c but if the responses are many and varied i will post a summary cheers mike mike abbott mabbot stellenbos csir co za cape town mabbot fred csir co za south africa
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re illusion i missed the first article s on this line due to not having a chance to read the news for a couple of days the idea is commercialized in at least one product the private eye that s a small cube shaped device that the user straps around the head similar to a sweat band there is a boom that comes from the side on which the device is mounted so that it is positioned in front of the user s eye the private eye we had here for evaluation was hercules mda compatible the innards are a row leds that are swept up and down by a galvonometer like movement the result is that the sweeping led bar forms a fused raster there is a virtual image projected in front of the user that the visual system tends to fuse with the background i didn t like the device very much i found it easiest to use if i looked at a blank white wall i had problems with focus tracking if i glanced down to look at my keyboard for an out of the way key the unit also emitted a soft buzz and vibration which i found annoying some people didn t seem to mind the buzz properly used however the image clarity was quite crisp i don t know if the company has taken the technology any further in the last year or two but it did seem to have promise bill mayhew neoucom computer services department rootstown oh usa phone wtm uhura neoucom edu n wed
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re adcom cheap products off shore assembly is one reason that adcom is able to make products that perform as well as those from people like audio research and van alstine and better than hafler and forte but at a much lower cost how do you spell tuna helper i gather by off shore assembly you mean that adcoms are built by blue fin tuna s who are into that squid fi sound i agree on that one my adcom preamp did sound better after installing the famous running the chips class a resistor mod and replacing the metal bottom cover with plexiglass too bad the factory could not make em sound better but better sound unfortunately does not appear to be a priority with adcom else the mods would neither have been necessary nor would they have improved what was already touted as superlative state o d art le sound i really want to hear from all those people out there who have traded up from an sp ii even an sp a to a gfp etc or maybe from those that have dumped their forte amps for a gfa etc
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re adcom cheap products i have an adcom gfa that i got in there certainly isn t anything magic about it the components used are decent but nothing uncommon with respect to consumer grade components the gfa is a nice piece of equipment i m glad that adcom had the guts to not over do the packaging it irks me when i see audiophile oriented equipment whose case and heat sinks probably cost much more and receive more attention than the electronics they are supposed to serve i don t see any big deal about the geographic region in which something is assembled this is especially true for something as low technology as a gfa i d hope that a gfa would still work well after several years except under conditions of extreme abuse there isn t much there to go wrong bill mayhew neoucom computer services department rootstown oh usa phone wtm uhura neoucom edu n wed
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re can microwaves be used to collect xyz coordinates in article apr cc usu edu writes in article c hs j ag bcstec ca boeing com rgc bcstec ca boeing com robert g carpenter writes it seems reasonable to me that a microwave transmitter receiver setup could do the job for example say you want to map an acre lot it d be convenient to place mw transmitters around the lot s periphery either or and then carry a hand held recorder and walk to a point on the lot press a button and the coords of the recorder s location is stored as digital data what s the chance of this working any systems like this already exist what kind of accuracy could you expect what would something like this cost to prototype is there a better alternative than microwaves of course you could develope this system but there is already a system called global positioning satellites it gives three dimensional coordinates anywhere on earth many surveyors use this system with a differential receiver transmitter to get coordinates within centimeters basic receivers with resolution of a few meters on a good day are available from many sources wmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmw weston r beal sldf sol ee usu edu sldf cc usu edu electrical engineer utah state university that s the wonderful thing about crayons they can take you to more places than a starship can guinon thought it means global positioning system there are two precision levels one for army applications killing has to be very accurate today and one for civil ones the civil precision is about to m correct me if i m wrong though it may be insufficiant for mapping buildings but there is a way with an additional reference point e g one fixed gps system in a house to get the same high precision as the military version but it gets pretty complicated then if you use a microwave system actually this means some type of radar you need quite a lot of number crunching to get accurate vectorized data out of your original signals so the gps system seems to be the better and running idea for your application there have been discussions in this newsgroup don t know of an address anymore cheers robert hb nby robert ganter universitaet basel i am a fan institut fuer informatik of my plan basel switzerland ganter ifi unibas ch amateurradio hb nby packet hb nby hb eas che eu
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re mysterious tv problem source if the set is direct line powered try checking the likely to be there hybrid regulator module down stream from the volt supply several sets i ve looked at use a volt regulator the regulators have a tendency to short out making the safety circuits shut down the eht supply section try putting the set on a variac or adjustable transformer and lower the ac input voltage to the set to about volts if the set operates nromally then you know you ve got a shorted regulator there are myriad other areas for problems but i ve seen the one above several times also if the set uses one the trippler module may be shot that s fairly common bill mayhew neoucom computer services department rootstown oh usa phone wtm uhura neoucom edu n wed
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shrunken monitor window does anyone know what causes the ever growing black border around the edges of my computer screen the growth has been gradual so i don t know how long it s taken to get this bad i have a dec color monitor maybe five years old and the black border is about inches on the left and right sides about inches on the bottom and negligible at the top of the screen the only controls are brightness knob contrast knob degauss switch and power switch is there anything to be done or are the monitor s days numbered larry hsu larryhsu mtl mit edu
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re dumb question function generator output offset obtain the service manual for the oscilloscope and adjust the internal output offset contorl there is virtual certainty that there is an internal ajustment for the offset control s zero detent position verify that the function generator is properly loaded many generators expect you to supply a ohm load go to a hamfest flea market and scrounge around for a pass through ohm terminator that has a male and female bnc or whatever connector on it the calibrator on my tektronix scope is designed to put out v into a meg load but volt into a ohm load you may also find that loading the output of the function generator also reduces the harmonic distortion build an attenuator you don t have to use and i wouldn t want to use the input impedance of the device under test as part of the voltage divider to drop the input test voltage consider this k ohm gen ohm d u t loaded think about the ratio of k and then think about the accuracy to which you can read voltages on your oscilloscope you can virtually discount the loading of the d u t also you have the millivolt test generator you want good luck bill mayhew neoucom computer services department rootstown oh usa phone wtm uhura neoucom edu n wed
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ic packages hi i am looking for some help in choosing a package for a high speed silicon adc mhz currently being fabricated this is a phd research project and i have to test the chip at speed on a pcb i expect to have roughly packaged circuits and will do dc low speed and high speed testing using different set ups for the test chip i know for sure that a dip will not work the long lead lines have too high an inductance getting a custom made package is too expensive so i am trying to choose between a flatpak and a leadless chip carrier the flatpack would be hard to test since it has to be soldered on to the test setup and i would spend loads of time soldering as i kept changing the test chip the leadless chip carrier sockets also have long lead lines and may not work at high speeds does anyone out there have experience knowledge of this field i would greatly appreciate help any ideas names of companies manufacturing holders sockets packages would help p s the multi layer fancy gaas packages seem like a bit of overkill seema varma
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re what do nuclear site s cooling towers do just to complete that thought the cooling towers cool water that circulates through heat exchangers that recondense the turbine exhaust back into feedwater for the heat exchangers that transfer energy from the reactor s cooling circuit turbine etc reactor c t the reactor has a closed loop circuit to prevent radioactive contamination of the the turbine feedwater the cooling tower is a separate circuit to avoide contamination of the turbine feedwater with atmospheric contamininats etc purifying boiler feedwater is important business at both fossil fired and nuclear generation facilities bill mayhew neoucom computer services department rootstown oh usa phone wtm uhura neoucom edu n wed
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electrical properties of elastomers hello i am looking for carbon doped rubber or an highly elastic material that changes its resistivity or some other electrical property when streched if you could email me any info you may have on material names or companies that make the stuff it would be highly appreaciated thanx jp biomedical engineering louisiana tech university
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re picking up cable tv with an aerial great the first advantage of cheap coax i ve ever heard cheers robert hb nby robert ganter universitaet basel i am a fan institut fuer informatik of my plan basel switzerland ganter ifi unibas ch amateurradio hb nby packet hb nby hb eas che eu
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re what do nuclear site s cooling towers do in article qlg o d q sequoia ccsd uts edu au writes i really don t know where to post this question so i figured that this board would be most appropriate i was wondering about those massive concrete cylinders that are ever present at nuclear poer sites they look like cylinders that have been pinched in the middle does anybody know what the actual purpose of those things are i hear that they re called cooling towers but what the heck do they cool i hope someone can help this is definitely the wrong newsgroup for this but never mind any machine powered by heat motor steam or gasturbine steamengine thermoelement etc work the better the bigger the temperature difference between input and output is because you never get all thermic energy out of the powering medium steam burning gaz etc you have to eliminate the rest of the energy to keep the efficency high a thermal electric power plant coal oil or atomic power works just the same way you heat water steam to power the turbine and generators because you don t get the whole energy out of the steam efficency is never you have to cool down this steam again by something else most power plants use cooling towers for this purpose some type of mega refrigerator others use water of a river ecologically not unobjectionable got it cheers robert hb nby robert ganter universitaet basel i am a fan institut fuer informatik of my plan basel switzerland ganter ifi unibas ch amateurradio hb nby packet hb nby hb eas che eu
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re a question about v so here s my question it seems to me that i d have the same electrical circuit if i hooked the neutral jumper from the neutral over to the ground screw on new three prong grounding outlets what s wrong with my reasoning here first go to the local hardware store and pick up a copy of wiring simplified by h l richter now if your house is wired with metal conduit you don t need a seperate ground wire assuming the house is wired correctly and the pipes are connected to a cold water pipe in your basement the outlets that have a neutral hooked to the ground screw seem wrong anyone else think so back in the s i was a service technician for a cash register company the cash registers used microprocessor circuits and back then they were very susceptible to electrostatic discharge and line noise the biggest problems came from outlets that were not properly grounded in almost every place we went to do an installation we found outlets with the ground connected to the neutral for of the things you can plug into one of these they work fine for our cash registers they were a nightmare line noise tended to scramble the memory periodically with modern electronics using switching power supplies this should be less of a problem even the company i used to work for is no longer recommending a dedicated line with a seperate ground for their equipment i imagine if you check most household wiring you will find that the ground and neutral are connected although not ideal it should be o k for most applications slmr my reality check just bounced the ozone hole bbs a private bulletin board service full service nodes usrobotics k bps gigs files skydive new orleans rime network mail hub usenet newsgroups please route all questions or inquiries to postmaster ozonehole com
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husky programmer bits req d help i m looking for a isa driver card and driver software for a logical devices husky programmer it aint mush good without these can anyone help with either of these items cheers mike
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re receiver system one thing to consider is time division multiplexing the emg channels to reduce the number of rf carriers you have to generate if you multiplexed the emg inputs at khz that would probably be sufficient for most physiology studies you d have hz per channel sampling rate that level of analog multiplexing should be rather easy to accomplish combining a lot of rf carriers is pretty tricky to do without generating intermodulation a system to be carried by a runner is in a fairly harsh environment and would probably be difficult to keep balanced a commercial hand held transciever could probably be employed with a little modification to accomodate widening the bandwidth obviously this has to be done in accordance with whatever laws govern the use of transeivers in your location bill mayhew neoucom computer services department rootstown oh usa phone wtm uhura neoucom edu n wed
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casio sf serial link the casio lectric diary has a wire serial interface with param setting like rs for which one get a magic but expensive cable to connect to a pc does anyone know the spec of this interface e g it needs inverting and boosting from cmos signals to match rs lines chris malcolm cam uk ac ed aifh department of artificial intelligence edinburgh university forrest hill edinburgh eh ql uk dod
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re a question about vac outlet wiring in article cmkrnl com jeh cmkrnl com writes in article apr ecsvax uncecs edu crisp ecsvax uncecs edu russ crisp writes so here s my question it seems to me that i d have the same electrical circuit if i hooked the jumper from the neutral over to the ground screw on new three prong grounding outlets what s wrong with my reasoning here what you can do if you want three prong outlets without additional wiring is to use a gfci outlet or breaker but the outlet will be cheaper in fact depending on where you are putting your new outlet s a gfci may be required you still need to supply a proper ground for a ground fault circuit interrupter so rewiring is still a part of this job however the ground may be connected to a local earth ground rather than back at the breaker box as jamie said gfci devices are required by code in a number of places most notably bathrooms and outside the house i do suggest the use of gfci outlets rather than the breakers you will end up with much less headaches noise pickup in long cable runs is sometimes enough to cause frequent tripping of the breakers gfci devices do save lives if you decide to install them be sure to check them regularly using the test button running the family business electrical supplies and lighting for many years i have seen too many seasoned electricians fried because they forgot to double check their common sense list please exercise caution gary gendel vice president current consulting assignment genashor corp mentor graphics corporation piney woods drive independence boulevard belle mead nj warren nj phone phone fax email garyg warren mentorg com
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chip chipset for code barcode distribution usa reply to lihan ccwf cc utexas edu while i m on the net bugging everyone is there such a thing as a chip or chipset to decode code barcode i ask for a couple of reasons mainly i want a reasonably compact encoding scheme to write information on magstripe cards and code appears to be about right if the right way to do it is something else and it s reasonably easy can someone let me know i might not get a chance to reply too quickly to this or my earlier post but i ll get to them within a couple days i think thanx everyone bgb lihan ccwf cc utexas edu
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7,182 |
sci.electronics
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radio shack battery of the month club radio shack has canceled their battery of the month club does anyone know why they say they ll honor existing cards in customer hands but no new cards will be issued don montgomery donrm sr hp com
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7,183 |
sci.electronics
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re what do nuclear site s cooling towers do s s walker man swalker uts edu au wrote i really don t know where to post this question so i figured that this board would be most appropriate i was wondering about those massive concrete cylinders that are ever present at nuclear poer sites they look like cylinders that have been pinched in the middle does anybody know what the actual purpose of those things are i hear that they re called cooling towers but what the heck do they cool i hope someone can help during the nuclear fission reaction the uranium fuel can get hot enough to melt when this happens the liquid uranium is pumped to the cooling tower where it is sprayed into the air contact with the cool outside air will condense the mist and it will fall back to the cooling tower floor there it is collected by a cleaning crew using shop vacs and is then reformed into pellets for reactor use the next day cooling towers are a lot taller than they really need to be power companies are forced to make them that tall by some enviromental law that requires the raw uranium emisions to be held to under this law is now under attack by lawyers arguing that the should be measured at the edge of the property rather than the edge of the cooling tower eliminating this law will save power companies thousands of dollars in concrete costs for new nukes john eaton hp vcd johne
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7,184 |
sci.electronics
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ungrounded gfcis was re a question about vac outlet wiring in article qmisf odp sdl warren mentorg com garyg warren mentorg com writes what you can do if you want three prong outlets without additional wiring is to use a gfci outlet or breaker but the outlet will be cheaper in fact depending on where you are putting your new outlet s a gfci may be required you still need to supply a proper ground for a ground fault circuit interrupter oddly enough you don t at least according to the wiring faq that is regularly posted on misc consumers house a gfci senses discrepancies between the live and neutral wire currents and cuts them both off if a discrepancy is found no ground connection is needed for it to function michael a covington associate research scientist artificial intelligence programs mcovingt ai uga edu the university of georgia phone athens georgia u s a amateur radio n tmi
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7,185 |
sci.electronics
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re looking for a good spice book in c gia x acsu buffalo edu neil b gandler v mb k ubvmsb cc buffalo edu wrote i am an electrical engineering student and its a must that i get familiar with spice i have been using it and getting used to it but it would be great to have a good reference manual that explains everything in an organized and concise i current have a guide to circuit simulation analysis using spice i feel it has the information is just randomly placed in the book and its not easy to look up small things when you just need a good reference book i would appreciate any info thanks there is a postscript manual at ic berkeley edu in pub spice um f ps directory about kbytes pages juhan poeldvere es qx juhan chem ut ee tartu university dept of chemistry fax jakobi st ee tartu estonia via stockholm voice
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7,186 |
sci.electronics
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sc sa specs hi could some kind soul post me the max power voltage current ratings of sc and sa transistors their conductance types and pinouts they are used in the sweep portion of a tv set thanks in advance juhan poeldvere es qx juhan chem ut ee tartu university dept of chemistry fax jakobi st ee tartu estonia via stockholm voice
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7,187 |
sci.electronics
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polaroid range finder interference help we have a setup with with polaroid transducers and rangefinders we would like to fire these three at a time with about ms between firings the three that are being fired do not fire in the same direction to further explain the situation assume we are firing sonars a b c ms apart each other we should normally see an echo on a that corresponds to the distance however sonar a detects the init line of sonar b the detection is actually through the transducer of sonar a we can see a very faint khz signal on the transducer exactly at the time the init line of sonar b is activated we feel that there is some ground coupling that is causing this interference we came to this conclusion since we are using a separate power supply for sonars b and c has anyone else had any problems with these particular units and this type of experience your suggestions for remedies will be greatly appreciated caglan m aras aras eceris ece ncsu edu ece department ph north carolina state university fx raleigh nc
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7,188 |
sci.electronics
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single chip receiver for fsk my next project is to come up with an if detector module for fast to kb sec packet radio use no fancy modulation scheme just wide fsk for use at or mhz i m a bit familiar with the motorola chip but i wonder if there are newer designs that might work at higher input frequencies my goal is to come up with an inexpensive design for a receiver back end with if input on one end and an fsk demondulator on the other i m particularly interested in ways to use a higher if than do any current chips work up to say mhz with internal downconversion so a normal if filter can be used any suggestions john john r ackermann jr law department ncr corporation dayton ohio john ackermann daytonoh ncr com packet radio ag v n acv oh tcp ip ag v ag v ampr
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7,189 |
sci.electronics
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re history question in article kazel uiuc edu kazel uiuc edu mitch kazel writes sorry if this isn t the correct news group but a colleague of mine is trying to find out when the first public use of electronic voice amplification was i e a p a system any reference would be appreciated please reply via e mail mitch kazel n hdq internet kazel uiuc edu this is vague so i am posting it in case anyone else knows more i recall reading of a phonograph which used mechanical amplification compressed air was squirted out of a valve which was controlled by the pickup the result was noisy and distinctly lo fi but much louder than a conventional phonograph it tended to wear the disks out pretty quickly though paul paul johnson paj gec mrc co uk tel ext these ideas and others like them can be had gec marconi research is not for each from any reputable idealist responsible for my opinions
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7,190 |
sci.electronics
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thermal fuse supplier wanted i have a thermal fuse from a apple laserwriter ii power supply made by cannon that i need to replace the fuse is not the standard tubular thermal fuse like those found in hair driers etc but is a rectangular plastic package much like a transistor or diode it is about x x with both leads coming out of one of the x sides i have been told that it was made by miti a asian company but i can find no information as to a supplier this fuse is rated at a c does anyone have a source for this fuse i only need or so which means that the manufacturer wouldn t even want to talk to me let alone deal with me please advise via e mail thanks pat i like boats and bicycles they re healthier than valium pat horne network manager shop supervisor hardware guru cs dept university of texas austin tx usa voice fax uucp cs utexas edu horne
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7,191 |
sci.electronics
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re network the same folks now have out lbl little big lan for i think you get it for if you already own network lbl works with arcnet parallel ports and serial ports in any combination for up to or so nodes no flames please but i picked up this discussion a bit late and i am really curious what exactly is the network something to hack together n serial cables something with n serial drivers thanks pat
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7,192 |
sci.electronics
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tdr plug in if anyone out there has an hp series scope or mainframe i have the tdr plug in the i believe for it and have no need to keep it interested e mail me dave medin phone w ssd networking h intergraph corp m s gd internet dtmedin catbyte b ingr com huntsville al uucp uunet ingr b catbyte dtmedin everywhere you look at least around my office the opinions expressed here are mine or those of my machine
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7,193 |
sci.electronics
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emulator pods a surplus dealing buddy of mine came up with two emulator pods hp c for hp development station target processor dip head does not include board that plugs into the applied microsystems c pod lcc head if you have an interest in either let me know they look to be in excellent condition he doesn t know what to do with them which may mean that they ll be cheap dave medin phone w ssd networking h intergraph corp m s gd internet dtmedin catbyte b ingr com huntsville al uucp uunet ingr b catbyte dtmedin everywhere you look at least around my office the opinions expressed here are mine or those of my machine
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7,194 |
sci.electronics
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re help how to construct home built battery for rd grade sci report dean anneser anneser pwa b uucp wrote my yr old son has signed up to do a science report on batteries i was wondering if anyone could provide me with some information as to how to construct a home built battery in my grade school days i remember seeing the ice cube tray version but i don t remember what to use as a good electrolyte or what the easily obtainable metals were thank you in advance dean w anneser pratt whitney aircraft computer system specialist m s desk fax main st ooo v uucp uunet pwa b anneser east hartford ct live to ride internet anneser pwfire pweh utc com one test result is worth one thousand expert opinions wernher von braun dean w anneser pratt whitney aircraft computer system specialist m s desk fax main st ooo v uucp uunet pwa b anneser east hartford ct live to ride the simplest one is easy take a lemon or other citrus type fruit and stick a pair of metal strips into it for the contacts the two strips must be of disimelar metals like copper and zinc then connect a voltmeter to the contacts and read the voltage bill xpresso uucp bill vance bothell wa rwing xpresso bill you listen when i xpresso i listen when uuxpresso
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7,195 |
sci.electronics
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re in article apr serval net wsu edu rwilley eecs wsu edu ronald willey cs writes the supra accelerator that is mentioned in one of the pervious articles is not or based it runs on a at mhz and the design they are using is very simple if you were referring to the a exteranal model hmm i don t think you and i are thinking of the same thing i was the original poster btw the accelerator that i m talking about almost certainly uses a hc according to the footnotes in the supra ad it only costs list so i really doubt if it has a mhz inside it s called the supra or supra turbo there s an external a model and an internal a model btw does anyone know if a mhz hc exists griff miller griff miller waii com use this for email my opinions are mine not western s dear friend do not imitate what is evil but what is good anyone who does what is good is from god anyone who does evil has not seen god john
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7,196 |
sci.electronics
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re a question about vac outlet wiring in article apr cmkrnl com jeh cmkrnl com writes in article apr ecsvax uncecs edu crisp ecsvax uncecs edu russ crisp writes i m considering modernizing some old wiring in my home and i need a little advice on outlet wiring several outlets are the old two prong type without the ground naturally the wire feeding these outlets is without the ground wire i noticed at the fusebox that some circuits have the with ground and that on these circuits the ground wire was tied to the same bus as the neutral white wire they are supposed to be connected together at the breaker panel but nowhere repeat nowhere else well almost there are strange exceptions for things like sub panels jamie hanrahan kernel mode systems san diego ca internet jeh cmkrnl com uucp uunet cmkrnl jeh cis not even in sub panels the only place the neutral should be connected to the ground is in a service disconnect in your house the main panel serves as the service disconnect sub panles in your garage or workshop for example must maintain seperate neutral and ground busses because they are not service disconnect equipment steve woodard kd kq not a licensed electrician but i can read the nec book my brother is though
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7,197 |
sci.electronics
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re exploding tv in article qk hj qos vtserf cc vt edu prasad vtaix cc vt edu prasad ramakrishna writes why would the picture tube explode or even smoke it s not the picture tube more likely the flyback emerson can t admire han prasad prasadr vtvm cc vt edu
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7,198 |
sci.electronics
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re making copy of a video tape victor inqmind bison mb ca victor laking writes you are experiencing what is called macrovision it is the protection that they use on the video tapes there are two ways around this that i know of first of all you can try using a different vcr to copy onto it is the input of the vcr that reacts to the protection so sometimes just switching the two vcrs around will take care of it some models just don t react to it does this also affect the viewing of tapes i have had problems with a couple of rented tapes they were virtually unviewable i fiddled with the tuning tracking and vertical hold but it was no good
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7,199 |
sci.electronics
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re beam robot olympic games next week in toronto does anybody know if there is a mailing list or newsgroup for power systems and related areas thanks luis g perez lperez eecs wsu edu
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