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sci.electronics
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re help with ultra long timing sounds like a job for a universal time reciever i don t know the logisitics of the situation but if you could just place a reciever in snow and place the oscillator in a nice lab somewhere else your problems should be solved just a suggestion wayne martin
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7,001 |
sci.electronics
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re hc problem mdanjou gel ulaval ca martin d anjou writes b votre host est mal configure bonjour sylvain j ai travaille avec le hc il y a ans et je ne me souviens pas de toutes les possibilites mais je vais quand meme essayer de t aider je ne crois pas que downloader une programme directement dans le eeprom soit une bonne idee le eeprom a une duree de vie limitee a cycles il me semble le communication break down vient peut etre du fait que le eeprom est long a programmer ms par bytes mais c est a verifier et que les delais de transfer de programme s vers la memoire sont excedes normalement les transferts en ram du code s est plus rapide car le ram est plus rapide que le eeprom en ecriture c est tout ce que ma memoire me permet de me souvenir bonne chance oh yeah easy for him to say ken thompson n itl ncr corp peripheral products division disk array development n rock road wichita ks ken thompson wichitaks ncr com
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7,002 |
sci.electronics
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re wire wrap questions again in article pascal apr ap apd cpg sony co jp pascal apd cpg sony co jp pascal goguey writes in article blue cis pitt edu macfitz pitt edu mark d fitzsimmos writes after a considerable amount of research review of discussions on this group and mainly fruitless time on breadboards i have decided that the path of least resistance for prototyping my not necessarily someone else s electronic designs is wire wrapping i have no idea about what you want to do but be careful wire wrapping increases a lot the wiring capacitance that shouldn t be a problem for slow applications i e a few mhz but as for quicker ones around mhz i doubt that it can work fortunately wire wrapping is a better wiring technique than most at high frequencies cray computers up to the x mp at least all had wirewrapped backplanes wirewrap gets into trouble at much higher frequencies than any ttl can handle the increase of wiring capacitance is not really relevant you have to use transmission line techniques and the capacitance is no problem where can i get a decent wrapping tool i d like to spend less than for an ac powered unit including bit and sleeve hand powered is the best there are good ac powered ones but rather expensive a low cost one doesn t work very well hand powered is a terrible choice imho unless you are a field maintenance person who will do maybe a dozen connections at a time your hands will cramp battery powered wire wrap guns are available in the range and so are the little twiddle stick manual types for a modest project of a couple hundred connections i d prefer to borrow a professional ac unit or a pneumatic one john whitmore
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sci.electronics
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re pioneer laser player in article apr ee rochester edu neale ee rochester edu reg neale writes i m trying to figure out how to operate a pioneer laserdisc ld that i bought at a surplus store it is reputedly from some kind of computerised viewing and or ordering system there is what may be an hpib connector on the back when i power it up the front panel power light comes on but no activity and the door doesn t open anyone have any experience with this unit or any ideas on how to obtain documentation what you have is one of the ld players from a video game dragon s lair space ace etc call pioneer technicial support at least that s the number i called them at and ask for the ld v interface guide it shows how the parallel interface should be wired and the codes for the commands play pause reject etc the guide is mainly for hooking the player to a computer but with a little work you could build a wired controller jim keais jkeais ucssun sdsu edu
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sci.electronics
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re help with ultra long timing in article pqu pmu sunb ocs mq edu au johnh macadam mpce mq edu au john haddy writes in article c wi g a athena cs uga edu mcovingt aisun ai uga edu michael covington writes don t use big capacitors they are unreliable for timing due to leakage true especially for electrolytic capacitors at high temperature instead use a quartz crystal and divide its frequency by times or something like that wouldn t a crystal be affected by cold my gut feeling is that as a mechanically resonating device extreme cold is likely to affect the compliance terminology of the quartz and hence its resonant frequency low power quartz oscillators are usually khz and these have significant temperature drifts which one doesn t often notice while wearing the watch on one s wrist low temperature sensitivity is available in other crystal types which unfortunately are larger and higher frequency mhz or so and take more battery power programmable timers might be less accurate but they are more power stingy than suitable crystal oscillators john whitmore
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7,005 |
sci.electronics
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level brightness xmas light set for easter yes i know it s nowhere near christmas time but i m gonna loose net access in a few days maybe a week or if i m lucky and wanted to post this for interested people to save till xmas note bell labs is a good place if you have a phd and a good boss i have neither subject xmas light set with levels of brightness another version of a variable brightness xmas light set this set starts with a blinker bulb string diagram orginal way set v b b rtn modified set for level brightness string v k w string b v rtn note no mods to wiring to the right of this point only one blinker is used note that the blinker would not have as much current thru it as the string bulbs because of the second string of bulbs in parallel with it that s why the use of the k w resistor here to add extra current thru the blinker to make up for the current shunted thru the second string while the blinker is glowing and the second string is not glowing when the blinker goes open this resistor has only a slight effect on the brightness of the strings s slightly dimmer s slightly brighter or use a w v bulb in place of the k resistor if you can get one caution do not replace with a standard c bulb as these draw too much current and burn out the blinker c approx w what you ll see when it s working powerup string will light at full brightness and b will be lit bypassing most of the current from the second string making them not light b will open placing both strings in series making the string that was out to glow at a low brightness and the other string that was on before to glow at reduced brightness be sure to wire and insulate the splices resistor leads and cut wires in a safe manner
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7,006 |
sci.electronics
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ftp sites anyone hello netters does anyone out there know any ftp sites for projects plans etc of an electrical nature jason jason blakey blakey ug cs dal ca
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7,007 |
sci.electronics
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intel rmx o s documentation wanted we ve just been donated a large machine for use in our robotics lab this device is complete with a based controller running the intel rmx operating system unfortunately we don t have any documentation on rmx can anybody out there in netland help please reply via email i don t regularly catch up with the news thanks david bull davidb mpce mq edu au
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7,008 |
sci.electronics
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re what is zero db in article sehari vincent iastate edu sehari iastate edu babak sehari writes in c true aa ms uky edu msunde mik uky edu mark underwood writes i am somewhat familiar with the db measurements as they apply to electrical circuits i e it is the gain of for example an amplifier measured on a logarithmic scale however this requires that you have a reference value i e the ouput is db e g with respect to the input signal stuff deleted what you actually talking about here is dbm and not db however the terms are used loosely by most people dbm is power with respact to mw whereas db is a ratio now like these two english statement i am doing well i am doing good similarly people usually use db for dbm another common mistake is spelling db instead of db as you did in your article see the b is for bell company the mother of at t and should be capitalized with highest regards babak sehari good gravy decibels are all ratios the question that remains in any ratio is the reference unit used sometimes this will be a reference power such as milliwatt given a certain circuit impedance which should also be included in the fine print or known like ohms in an rf circuit of that impedance leading to an accepted notation of dbm maybe it might be dbv disregarding the impedance of the circuit and power developed using volt as reference amplitude rather than reference power or it might have an arbitrary or omitted reference that is not included in the notation leading to just plain db so look at it this way db has an implied reference while notation such as dbm has an explicit reference for power db log p measured p reference for amplitude db log a measured a reference b is for bel which is a standard term for a log ratio to the base named after alexander graham bell a deci bel is of a bel it has nothing to do with the bell telephone company except for the common founder s name the small d large b is per si notation convention i don t know anyone that s been crucified for messing it up common references for audio are dbm milliwatt across ohms dbv volt vu a zero on the vu meter dbm pro gear line level vu dbv consumer gear line level often times a power amp vu meter will be aligned using the rated power of the amp as the db point it is all done to whatever reference is reasonable for the application or moment note that in a circuit with a given and maybe unknown linear impedance if the amplitude goes up so many decibels the power will also increase the same amount this proof can be done with the above two identities and ohm s law 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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7,009 |
sci.electronics
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re flyback squeal in video monitors in article mar ssc com markz ssc com mark zenier writes zack lau zlau arrl org wrote in sci electronics xhan uceng uc edu xiaoping han writes in article mar hubcap clemson edu michaet hubcap clemson edu michael d townsend writes brendan macadam mpce mq edu au brendan jones writes my mom s magnavox does this as well i put chewing gum all around the horizontal sync transformer so it wouldn t resonate the board as much don t flame it worked i realize that there is a more suitable substance available for this purpose but i don t remember what and where it is adhesive silicon from hardware store if it smells like vinegar it may damage metal surfaces by promoting corrosion anybody tried superglue cyanoacrylate this should sneak into the cracks better and is stiffer than silicone i ve found this works pretty well on noisy laminated power transformer cores and windings the hz kind likewise if anybody has tried this on a flyback i d like to hear about it i would suspect it would not be as effective as it was on power transformers as the material wouldn t damp as well something i suspect would be critical at the frequencies involved in other words you want absorption rather than prevention which would be real difficult at khz 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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7,010 |
sci.electronics
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re wanted a to d hardware for a pc in ncr mpd ftcollinsco ncr com brad wright writes if you know much about pc s ibm comp you might try the joystick port though i haven t tried this myself i ve been told that the port has built in a d converters this would allow the joystick to be a couple of pots if you could find the specs this might just work for you i guess k connecting pins x y x and y or get an bit da converter merely a couple of transistors and resistors and an opamp to compare its output to the voltage you want to measure connect them to a spared printer port if you have one and do the rest by software stepwise refinement the port addresses for your printer ports are probably h lpt h lpt this should work well enough for your purposes hope this helps gmd schloss birlinghoven postfach d st augustin frg e mail peter hendricks gmd de ph zi gmd dbp de ph gmd de
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sci.electronics
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re wanted a to d hardware for a pc in ncr mpd ftcollinsco ncr com brad wright writes if you know much about pc s ibm comp you might try the joystick port though i haven t tried this myself i ve been told that the port has built in a d converters this would allow the joystick to be a couple of pots if you could find the specs this might just work for you i believe that the a d converters found on a joystick port are really timers that tick off how long it takes an r c circuit the r being your paddle to charge up to something like vcc for games this works pretty well but you certainly wouldn t want to try to take lab measurements off something as non linear as that hmm i suppose you could linearize it in software but the real problem is that the precision of your measurement is no longer constant higher voltages would be more precise on the other hand i could be wrong and perhaps the game card designers splurged for the extra to make a cheap constant current source out of an op amp but i wouldn t expect that joel kolstad
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7,012 |
sci.electronics
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calculating a transformer help needed i want to convert a volt sinewave with frequency between khz and khz to a volt sinewave with the same frequency by means of a transformer the secondary current will be a ma what kind of transformer should i use ferrite can i buy one if so i need a partnumber and supplier if i cannot buy one how do i go about winding one myself what core do i use how big must it be in order not to saturate what thickness copper wire how many turns etc i know little about analog electronics so i hope some kind soul here will help me out pointers to relevant databooks will also be highly appreciated thanks mark de rooi rooi tpd tno nl
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sci.electronics
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re hv diodes in article hpfcso fc hp com myers hpfcso fc hp com bob myers writes nope the dag is on the outside of the tube and is grounded the inside aluminization is the second anode and is connected to the anode suction cup this with the glass of the tube in between is a capacitor and is used as the power supply bypass filter for the hv supply some smaller scope tubes don t have an aquadag coating on the outside if they are in mu metal shields you still have a capacitor actually and i think i said this in the original but perhaps wasn t clear enough there is usually both an internal and an external dag of the two the internal dag is the more important the aluminization of the back of the phosphor is in most cases not adequate to guarantee connection to the anode button and in the case where the gun assembly includes an accelerating electrode at anode potential most definitely does not provide that connection bob is indeed correct here in more than one way a look in the old rca picture tube manual backs this up as does sams reference data handbook the internal coating around the perimeter of the crt not the aluminum or tin crt face coating is referred to as a dag as well as the outer coating thankfully i didn t need to go to a f library to find it either one sparkling water for mr vanderbyl no caffeine in that is there 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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sci.electronics
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re sid chip to ibm system bus mr mc howell g h hippo ru ac za wrote please don t ask questions like why don t you buy a soundblaster the answer is simple overpriced considering the sound quality why not try one of the projects to build a dac connected to the parallel port as documented in some files which come with modplay these vary from a dac design to a simple single dac made only of resistors david hembrow eo europe ltd email dhembrow eoe co uk abberley house granhams road great shelford cambridge cb lq england
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sci.electronics
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heathkit zenith does anyone out there have the toll free catalog request and order line for heathkit zenith please post the number if you ve got it thanks
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7,016 |
sci.electronics
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re info on nec d multisync monitor myers hpfcso fc hp com bob myers writes i am looking for any info i can get on the nec d monitor i know that it is a multisync but that is about all i plan on buying one second hand in a while depending on its specs does anyone know the min max frequencies whether it is interlaced non interlaced or both video compatability etc i have seen a reference to it being pitch with x resolution and that it supports svga from one source and that it doesn t support svga from another source neither source seemed to have much reliable info so i don t want to take a guess i m at home right now and so am away from my monitor files the following is off the top of my head subject to revision worth what ya pay for it sort of info if you don t hear from anyone who has spec sheet in hand e mail me and i ll look it up if i m remembering correctly the d is a mm pitch multisync that covers at least vga khz horizontal hz vertical to x hz which is going to be about khz horizontal it may go somewhat higher than that on the horizontal but you won t be happy with anything beyond x on a tube you probably won t be too thrilled with the x on this tube but it will sync up and display it i prefer at least a for this resolution since svga is x it ll do that too the horizontal range probably goes lower than but i don t know if it goes all the way down to straight ntsc rate tv which need about khz sweep as far as video compatibility if i m reading the question right it won t take anything but analog rgb inputs in other words it has no way to decode ntsc or y c video inputs you would need some sort of board to to this conversion like the sorts of things that let you display ntsc on a vga display hopefully now i ll see this response of mine and it ll remind me to look this stuff up and confirm it or force me to post a hasty retraction ok i was under the impression that it accepted digital input i still don t know for sure if it accepts both interlaced and non interlaced as i have gotten conflicting info victor inqmind bison mb ca the inquiring mind bbs winnipeg manitoba
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7,017 |
sci.electronics
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wide band analog time delay hi there i am looking for a wide band analog time delay not phase delay variable from microseconds to milliseconds please reply via email to rrc firga sun ac za
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7,018 |
sci.electronics
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re a to d hardware for a pc if you can find a copy of assembler language programming the ibm pc by willen and krantz nd ed pub by sams there is a discussion of the game control adapter monostable multivibrators and conversion to other uses as well as an assembler program if you need greater accuracy there is no reason you couldn t modify the approach to suit your needs jim
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7,019 |
sci.electronics
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re homebuilt pal epld programer in sci electronics timd fenian dell com writes anyone know a reasonable circuit for programming pals i am interested in programming a wide range of eplds but would be happy with something that could handle a v or thereabouts i too would be interested in any information on the subject of programing pals etc better to know what your on about before you start something i always say often saves you a packet as well thanks in advance chris name mr chris smith twang on that ole guitar addrs scst uk ac liv uni liverpool university quest to build more and more hardware dgree computer science what ever the sun may be it is certainly not a ball of flaming gas d h lawrence all views expressed are my own and reflect that of private thought
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sci.electronics
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re heathkit zenith in article c egz t austin ibm com login austin ibm com writes does anyone out there have the toll free catalog request and order line for heathkit zenith please post the number if you ve got it thanks
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7,021 |
sci.electronics
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re principle of the breathalyzer william burchill williamb ee ubc ca wrote does anybody out there know how the hand held breathalyzer used by our police works i would like to hear about this and the more general problem of detecting smells by machine thanks william williamb ee ubc ca from what i have read about these little gadgets it works on a electrochemical galvanic principle the sensing unit has a chemical matrix which produces an electrical voltage proportional to the amount of chemical compound it is designed for in this case i believe it is the hydroxyl group i have also heard not tested since common gasoline is also a member of this hydroxyl group it will also cause a failing breathalizer failure next time you get stopped for dui say you just siphoned gas from your neighbors car you know the oklahoma credit card and chances are you won t get a dui ticket jerry long long spk hp com disclaimer opinions are my own and do not reflect those of my employer
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7,022 |
sci.electronics
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rf data transmission i need a off the shelf method of transmitting small amounts of data up to feet the data is low speed and can be encoded as needed low power on the transmitting end would be a plus an fcc certified product would be prefered if you have any pointers to products or companies i d appreciate hearing from you thanks ken
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7,023 |
sci.electronics
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re jacob s ladder in article c z x b murdoch acc virginia edu dgj y kelvin seas virginia edu david glen jacobowitz writes i ve been wanting to build a tesla coil for quite awhile now who doesn t right and i thought it would be a good intermidiate step to build a jacob s ladder first well i have been looking for a high voltage transformer that is reasonable inexpensive neon sign transformers cost mucho in the past i ve managed to buy used neon sign transformers from sign shops for about try calling around warren n massey massey travis llnl gov lawrence livermore national laboratory east ave p o box l livermore calif my opinions are mine alone
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sci.electronics
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re help with ultra long timing in pqu pmu sunb ocs mq edu au johnh macadam mpce mq edu au john haddy writes in article c wi g a athena cs uga edu mcovingt aisun ai uga edu michael covington writes instead use a quartz crystal and divide its frequency by times or something like that wouldn t a crystal be affected by cold my gut feeling is that as a mechanically resonating device extreme cold is likely to affect the compliance terminology of the quartz and hence its resonant frequency yes but in a fairly reproducible way is only a smidgen of the distance to absolute zero and in any case you re going to have to borrow freezer space from a bio lab or someone to test calibrate this darling anyway btw you re probably going to want those big capacitors you found to fire the solenoid high current drain on frozen batteries can be an ugly thing paul
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sci.electronics
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re what is zero db joseph chiu josephc cco caltech edu wrote sehari iastate edu babak sehari writes similarly people usually use db for dbm another common mistake is spelling db instead of db as you did in your article see the b is for bell company the mother of at t and should be capitalized thus a decibell deci l tenth of bell is a fractional part of the original bell for example southwestern bell is a decibell out of what hat did you pull this one db is a ratio not an rboc and the measure of current amp is actually named after both the amp company and the amphenol company both companies revolutionized electronics by simulatenously realizing that the performance of connectors and sockets were affected by the amount of current running through the wires sorry the unit for current is the ampere which is the name of a french man named ampere who studied electrical current the term amp is just an abbreviation of it the company amp came after the ampere unit was already in use the ohmite company was the first to characterize resistances by numbers thus our use of the ohms i don t know about this one but it doesn t sound right alexander graham bell actually is where bell came from well you got one thing right actually bel refers with highest regards babak sehari joseph chiu josephc cco caltech edu os you gotta get this thing msc caltech pasadena ca os the operating system of tomorrow today greg moffatt bell northern research inc ottawa canada my opinions not bnr s
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sci.electronics
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re police radar just how does it work in article apr walter bellcore com deaddio ski bellcore com michael deaddio writes question if i am right about the doppler if i spell it different every time maybe one will be right effect how does the radar get an accurate reading when the car containing it is moving it would seem to me for all thats worth that it would need to be calibrated with the speedometer of the car containing it i am fairly sure this isn t the case so whats the deal essentially this is actually how it is done the radar gun is tied into the speedometer of the car no it is independent of the speedometer the gun processes two doppler returns the speed of the car relative to the pavement and the speed of the target taking the difference between the two some guns with a moving mode actually have a split beam with one beam aimed preferentially at the pavement car and driver had a good article on traffic radar but it was back in i used its contents and references to defend myself against a bogus radar measured ticket it detailed moving mode which is easier to defend against because of the increased amount of variables 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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sci.electronics
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re books info on audio dsp in sci electronics rec audio david s rowell writes i assume these are appropriate newsgroups for this question i am looking for a good book articles anything on audio dsp theory is nice but i m really looking for something very much on the applications side i want to look into it as my new hobby so i need all the direction i can get any comments would be welcome too i m looking to build a dsp for guitar processing hence lots of background information would be really useful if anyone s got any info could they email thanks in advance chris name mr chris smith twang on that ole guitar addrs scst uk ac liv csc uni liverpool university quest to build more and more hardware dgree computer science what ever the sun may be it is certainly not a ball of flaming gas d h lawrence all views expressed are my own and reflect that of private thought
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sci.electronics
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pc games joystick port subject says it all could someone tell me the pinout for a pc type analogue joystick port joystick a vdc button x axis ground ground y axis button vdc joystick b vdc button x axis ground y axis button vdc slmr soft judges make hardened criminals 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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sci.electronics
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re police radar just how does it work in article apr walter bellcore com deaddio ski bellcore com michael deaddio writes the beam is split in two with one beam aimed at the target car sort of and the other at the ground the speeds of each are calulated for the final number actually this is true on the more expensive ones but the cheaper ones just read the speedometer i ve never seen a speedometer reading model are you sure who makes them consider the difficulty of reading the speedo on various makes of cars in use i ve seen single beam moving mode and split beam moving mode 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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sci.electronics
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re hv diodes in article apr mprgate mpr ca vanderby mprgate mpr ca david vanderbyl writes dtmedin catbyte b ingr com dave medin writes the crt in fact does have an intentional built in capacitor for its function just as ic s have built in transistors etc gee mr myers are we going to let this go without a correction two things read your own posts i was agreeing with bob no correction needed don t quote stuff out of context 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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7,031 |
sci.electronics
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re what is zero db moffatt bnr ca john thomson writes out of what hat did you pull this one db is a ratio not an rboc sorry the unit for current is the ampere which is the name of a french man named ampere who studied electrical current the term amp is just an abbreviation of it the company amp came after the ampere unit was already in use i don t know about this one but it doesn t sound right well you got one thing right hello john oh nevermind jeff jeffrey s curtis sidewinder uiuc edu resplendent in full regalia they the power of free at uiucvmd revel in their role as self appointed sony phase linear sanyo sennet critics of the establishment jensen polk streetwires proton inxs welcome to wherever you are
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self modifying hardware permit me to quote fragments of praetzel sunee uwaterloo ca s article out of context newsgroups sci electronics comp lsi cad from praetzel sunee uwaterloo ca eric praetzel date feb gmt currently the xnf format is propierty and i know of at least on person at a university who was able to get it after signing a non disclosure agreement the xilinx bit map format is pretty well top secret i would love to know it because then you could make self modifying hardware as it is i had to reverse eng the xilinx tools to dump the bit map to the fpga because it only runs on the computer with the hardware key self modifying hardware could be very interesting computers that could write thier own programs assemblers compilers were an immense breakthrough from calculators that couldn t i eagerly await a programmable gate array which uses a pd format and does not cost your first born to program till then we will keep on reverse engineering whatever we can as it is one company that i worked at has gone under fpgas are what they needed to make their product competitive they could not afford them in the end you could say that they could not afford to not use them but the management discovered that too late eric my condolences i can t even imagine what i could do with self modifing hardware i can imagine self modifying software and even though all my teachers say that s bad even worse than goto check out what the experts used to say about self modifying code he uses orders rather than opcodes on the principles of large scale computing machines by goldstine and von neumann collected in john von neumann collected works vol v reprinted here with absolutely no permission from anyone we plan to have a full size binary digit word hold either contain full size number equivalent to decimal digits but we will use the first binary digit to denote the sign or two binary digit orders it should be added that this technique of automatic substitutions into orders i e the machine s ability to modify its own orders under the control of other ones among its orders is absolutely necessary for a flexible code thus if part of the memory is used as a function table then looking up a value of that function for a value of the variable which is obtained in the course of the computation requires that the machine itself should modify or rather make up the reference to the memory in the order which controls this looking up and the machine can only make this modification after it has already calculated the value of the variable in question on the other hand this ability of the machine to modify its own orders is one of the things which makes coding the non trivial operation which we have to view it as david cary tenor e and comp engineering finger caryd a cs okstate edu s e ave tulsa ok usa sol universe v david cary tenor e and comp engineering finger caryd a cs okstate edu s e ave tulsa ok usa sol universe v
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sci.electronics
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re what is zero db in article pkveuinnduk gap caltech edu joseph chiu writes the ohmite company was the first to characterize resistances by numbers thus our use of the ohms yeah right and the company was started by george simon ohmite rich
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sci.electronics
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re help with ultra long timing wellison kuhub cc ukans edu writes i have a project that was drooped in my lap that is somewhat a pain to design what i am looking for is a stable ultra long solid state timer what they want to do is to place this thing on the antartic ice shelf and measure the amount of snow fall over a period of six weeks every two weeks they want to trip a selonoid to discharge different colored pellets by gas pressure out across the snow then by digging down into the snow the snow fall amount can be measured as they come to the different color pellets the problem is trying to build a timer that would stand the cold degrees and a power source that wouldn t drain i have looked at the xr timers and the standard ne dual timers but thier temp specs won t go that low also two weeks equates to seconds per firing which means one big timing cap i have found farad yes farad caps that have a working voltage of volts and are small in size why are you fooling around with analog for this job a single chip micro and a crystal will do the job reliably and easily an only costs about that and a crystal and you re in business embed the whole thing in a foam insulated blanket power it from a solar cell use the excess power to heat the assembly during the day and rely on the insulation to hold the heat during darkness if you don t want to try thermal management contact someone like icl and have them cut you a special low temperature crystal it ll cost at most if you use a single chip micro you re looking at a parts count of maybe a processor a crystal two caps on the crystal a power fet to fire the solenoid a flyback diode and a battery this is fewer parts than you can build an analog timer for and is infinitely more reliable add a power zener diode for heat and a solar cell and the parts count screams up to pd assemblers are available for all the common single chip micros this application is so trivial you could even look up the op codes in the programmer s guide and create the binary with a hex editor john john de armond wd oqc interested in high performance mobility performance engineering magazine tm interested in high tech and computers marietta ga send ur snail mail address to jgd dixie com perform dixie com for a free sample mag need usenet public access in atlanta write me for info on dixie com
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radar detector detectors they detect the oscillator operating in the detector saw a story about their use in canada now don t go putting oscillators in your cars
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voltage multiplier problem hi i ve just built a valve preamp and use a diode capacitor voltage multiplier to step the vac supply voltage up to approx vdv as the load resistance increases the rc constant decreases and hence the output voltage drops i need as high an output voltage as possible about v the circuit consists of seven voltage multiplier stages ie diodes and capacitors each capacitor develops about v across them and i take the output from across seven capacitors v each capacitor is mfd at v if i increase each of the capacitors rating mfd that will increase the rc constant and hence alleviate some of the problem these capacitors are going to be a little expensive as i need of them so what would happen if i connected a mfd at v capacitor in parallel with the output and hence in parallel with the seven mfd capacitors will it as i assume increase the c in circuit and hence increase the rc time constant if it does and my output voltage becomes more stable by doing this then i will have killed two birds with one stone as i am experiencing some hz ripple and hence amp hum and this new capacitor will smooth this out and can anyone recomend a suitable value for an inductor choke to be placed in the output line of the power supply to filter out the hz mains hum lowest resistance possible i ve not got my preamp with me at the moment because it is too much of a distraction i m at university and i ve got to get my dissertation finished in two weeks hence i m mailing not playing with my solderoing iron it ll be cheaper too in the long run especially if new large capacitors don t work as planned email please can t always read the net thanks in advance chris name mr chris smith twang on that ole guitar addrs scst uk ac liv csc uni liverpool university quest to build more and more hardware dgree computer science what ever the sun may be it is certainly not a ball of flaming gas d h lawrence all views expressed are my own and reflect that of private thought
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speaker design software hi i m looking for software to aid a friend of mine with designing speakers does this type of software exist if anyone can point me toward a shareware or freeware product with this description that would be ideal steve van der burg using a friend s account p s excuse the terseness of the message i m having difficulty stringing readable sentences together today for some reason luke koops
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sci.electronics
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electric power line balls power lines and airplanes don t mix in areas where lines are strung very high or where a lot of crop dusting takes place or where there is danger of airplanes flying into the lines they place these plastic balls on the lines so they are easier to spot
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re electric power line balls in article apr eagle lerc nasa gov fsset bach lerc nasa gov scott townsend writes i got a question from my dad which i really can t answer and i d appreciate some net wisdom his question is about some diameter balls which are attached to electric power lines in his area he s seen up to a half dozen between two poles neither of us have any experience with electric power distribution my only guess was that they may be a capacitive device to equalize the inductance of the grid but why so many between two poles anyone know what they really are is there a related faq for this is there a better group to submit to we d both appreciate some enlightenment the balls are used to reduce the amplitude of oscillations of the wire during periods of high winds i ve seen what looks like paint cans filled with concrete used for the same purpose mike behnke senior tech advisor quid est illuidin aqua fermi nat accel lab equipment suuport batavia il computing div pistrix pistrix behnke fnalf fnal gov my opinions are my own not of the lab so if you don t like them call uwh iner
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re oscilloscope triggering in article c vs g ux murdoch acc virginia edu dgj y kelvin seas virginia edu david glen jacobowitz writes can someone out there explain exactly what the trigger feature found on oscilloscopes does lots og good explanation deleted lots more deleted is it just me or does anybody else out there not like digital scopes my school has some beauutful mhz hp that are digital with all the bells and whistles including soft keys which i think are a loveley touch that is software keys you don t forget that you are dealing with a computer those scopes even with all their neatness still make the ickyest looking waves lotsa features but ugly output and those are the best digitals i have ever seen i ve seen a lot of cheaper digitals and they look terrible i think the hangup with digital scopes is that you have to know so much more about them and how they work on a scope by scope basis and some of the functions are typically presented in my opinion in a counter intuitive fashion hp has made some strides in their series imo automatic setups are fine for simple repetitive waveforms but can give you some crazy results on more complex events where you need to understand how the scope is actually measuring processing the event for example is the scope in equivalent time or in real time sampling mode equivalent time being a mode where samples are built up slowly by adding a delay to the trigger event each sweep what was the scope s actual sampling rate at the time how is the data being massaged after capture but before display etc one common misconception is the speed of the scope is the hp scope you re using really a mhz scope or is it a mhz sample rate scope mhz single shot significance whose front end including s h can support mhz waveforms important for equivalent time sampling the mhz input in this case really only helps you when your waveform is repetitive or on a single sample when you get lucky and hit a transient event during a sample time so there are a lot more variables in understanding how to get useful information from a digital scope i prefer an analog scope for general use and the digital for events where i need storage for later analysis or comparison when the event is within the capability of the scope now for the price of true mhz digital scopes to fall 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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looking for ad pc board this is for a friend of mine please send answers directly to him e mail adress see below highspeed analog digital pc board hello ladies and gentleman i am looking for a highspeed a d pc board with a sampling rate above mhz an a resolution of bit the sampling rate can be arranged by an interleave mode where the time equivalent sampling yields or times higher sampling rate than the a d converter uses in non interleave mode the board must content an a d converter similar to analog devices ad or ad or if available a faster on if you a pc board bit slot isa with this specification or better please send me an email hansch cdc ikph uni hannover dbp de or a telefax to thanks in advance for your help sincerely matthias hansch ikph university of hannover germany andreas heinbokel heinboke tnt uni hannover de all wisdom is print on t shirts
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re what is zero db in article apr bnr ca moffatt bnr ca john thomson writes joseph chiu josephc cco caltech edu wrote thus a decibell deci l tenth of bell is a fractional part of the original bell for example southwestern bell is a decibell out of what hat did you pull this one db is a ratio not an rboc and the measure of current amp is actually named after both the amp company and the amphenol company both companies revolutionized electronics by simulatenously realizing that the performance of connectors and sockets were affected by the amount of current running through the wires sorry the unit for current is the ampere which is the name of a french man named ampere who studied electrical current the term amp is just an abbreviation of it the company amp came after the ampere unit was already in use the ohmite company was the first to characterize resistances by numbers thus our use of the ohms i don t know about this one but it doesn t sound right alexander graham bell actually is where bell came from well you got one thing right actually i think j chiu knows the score and is just being silly however decibel is in fact th of a bel he is right on that one but i don t know if it was accidental or not strictly defined a bel is the ratio of the log of two power levels and a decibel is th of a bel so you have x decibels for every bel hence bel log p p and decibel xlog p p the bel ohm volt farad ampere watt hertz henry etc are all named for pioneers in the field it s a traditional and fine way to honor researchers who discover new knowledge in a new field hertz was one of the most important of the early electronics explorers but had been left out in having a term or unit named after him until recently s prior to that what is now a hertz was a cps all the other units were defined many decades earlier
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re police radar just how does it work i ve seen several references to split or separate beam radars which i claimed didn t exist gotta eat some crow here i wasn t aware of them all i really knew was that it can be done with one beam i believe the rest of what i said is accurate though mmmmmmm crow oops wrong group
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radar detector detectors here s one i hope some knowledgeable readers will make a comment or contribution to in the state of virginia radar detectors are illegal period if you are caught with one it will be confiscated on the spot and will not be returned until after you appear in court and pay your fine the fine for having a radar detector accessible in a motor vehicle even if it is not on is sorry tourist ignorance of the law is no excuse they will get you too it used to be that the only way the law could be enforced was for an officer to actually see the radar detector not any more many law enforcement agencies are now using radar detector detectors right a super sensitive receiver that is capable of picking up rf from the radar detector itself my first reaction was no way but guess again these little buggers really work and the police are writing citations right and left for people using radar detectors one news story quoted an officer as saying that he had found the radar detector in all of the cars he stopped except one and he could never figure out where it was but he knew it was there this tends to make one assume there are few false arrest now before i get flamed please understand that i do drive at or near the speed limit i do not need a radar detector to keep me from getting a speeding ticket but i do like to know when my speed is being clocked or a speed trap is functioning my radar detector now stays locked in my trunk when i am in virginia which is what they want and yes what the law says and i intend to obey the law and is only used in states where it is legal for my fellow hams i am not a microwave person my mind only works in the hf spectrum between and meters microwave enlightment may be necessary 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 randy t agee ars wb bzx at some point you probably pondered the p o box th floor meaning of life and you came up with a virginia department of education satisfactory answer which has or has not richmond va stood the test of time or you shrugged phone mightily muttered beats the heck out of ragee vdoe vak ed edu me and ordered a cheeseburger
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re why is telephone audio hz telephone systems have the capability of a passband of hz to khz the reason they do not implement this is it is not backward compatable to every telephone system in addition the most effecent mix of electrical effecency and intelegability closly mateches a hz khz passband close but no banana to paraphrase garfield the reason hz is used is that voice channels used to occupy khz bands when multiplexed on a trunk line therefore hz at the bottom and hz at the top of this band were filtered to minimise interference with the next band nowadays digital trunks have made this less relevant but the phone companies still see no reason to improve quality especially for free therefore digital chunk of a trunk segments still have a guaranteed bandwidth of only khz so they can carry the equivalent of one analog line at the clock rate of a standard pcm t or e digital trunk it s all historical here in the uk the bandwidth restriction apparently only apply to local lines ie those used by the average domestic client private lines which are run from the local exchange to the leasing client are usually capable of a higher bandwidth if the exchange is digital don t quote me on that but i think i remember a bt engineer saying something to that effect when i was doing some work shadowing a few years ago byeeeee chris name mr chris smith twang on that ole guitar addrs scst uk ac liv csc uni liverpool university quest to build more and more hardware dgree computer science what ever the sun may be it is certainly not a ball of flaming gas d h lawrence all views expressed are my own and reflect that of private thought
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video io ideas have anyone some idea about how to build a cheap low resolution or high video projector example a lcd and an slide projector
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re books info on audio dsp in article c dsd pb compsci liverpool ac uk scst csc liv ac uk chris smith writes i m looking to build a dsp for guitar processing hence lots of background information would be really useful if anyone s got any info could they email well i m not sure i d use this to process a guitar but there was a audio filter dsp construction article in the sept issue of qst magazine ham radio oriented the dsp is available in kit form for about this particular dsp filter was targetted toward processing audio to remove noise static i built it and it really works well the source code is available too it makes a noisy audio signal much easier to hear note that this is for communication applications and is not high fidelity mike linnig texas instruments inc of all statistics are made phone call n qaw up most of them percent internet mike linnig dseg ti com are wrong
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how to kill ac inductive load spiking is there a fast n dirty way to kill the line spiking that occurs when an inductive load is turned on sometime other than at zero crossing of the ac cycle a capacitor kludged in somehow etc i ve got a microcontroller that is running a bunch of valves and pumps in a big instrument washer and almost everything is being switched with zero crossing solid state relays so that stuff stays quiet ac wise but there s one steam valve that gets turned on by a mechanical relay in the water tank fill thermostat system and it s not under control of my ssrs and it does sometimes generate radiate a spike that resets one of my peripheral chips my software times out and tries again but i d love to just tack in a magic spike killing fix that would avoid having to do some major rewiring redesign a varistor would help but might not be sufficient ideas paul marxhausen university of nebraska lincoln grace happens
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re police radar just how does it work in article apr b news b ingr com dtmedin catbyte b ingr com dave medin writes in article apr walter bellcore com deaddio ski bellcore com michael deaddio writes the beam is split in two with one beam aimed at the target car sort of and the other at the ground the speeds of each are calulated for the final number actually this is true on the more expensive ones but the cheaper ones just read the speedometer i ve never seen a speedometer reading model are you sure who makes them consider the difficulty of reading the speedo on various makes of cars in use i ve seen single beam moving mode and split beam moving mode obviously the police officer reads the speedometer i cannot believe the nit picking in this group there s beams there is not is too etc dave medin s line sig deleted
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re radar detector detectors ragee vdoe vak ed edu randy agee writes it used to be that the only way the law could be enforced was for an officer to actually see the radar detector not any more many law enforcement agencies are now using radar detector detectors right a super sensitive receiver that is capable of picking up rf from the radar detector itself my first reaction was no way but guess again these little buggers really work and the police are writing citations right and left for people using radar detectors one news story quoted an officer as saying that he had found the radar detector in all of the cars he stopped except one and he could never figure out where it was but he knew it was there this tends to make one assume there are few false arrest from what i understand about radar dectectors all they are is a passive device much like the radio in your car they work as an antenna picking up that radar signals that the radar gun sends out therefore there would be no way of detecting a radar detector any more than there would be of detecting whether some one had a radio in their car neal howland nhowland matt ksu ksu edu
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re where do u look in article apr cmkrnl com jeh cmkrnl com writes i might add that collecting last year s data books or even ones two years out of date is usually pretty cheap and has benefits besides you usually don t want to base a design on a brand new chip there may be bugs availability may be limited the data sheets may be missing critical information that will show up in the ap notes in next year s data books kinda like buying version of a major new software package sometimes you get lucky but don t count on it there are two more reasons to save old databooks and then beyond two years obsoleted parts and better application notes and tutorials when a part is dropped from future production planning such as the national mm series white noise generators camera sync generators etc it will disappear from current databooks although it still may be produced for a short time or be available from stock somewhere now if you have some old plans calling for such a device or you have a dead gadget on your workbench and it has such a part in it you ll know the functions so you can troubleshoot and substitute as necessary the old ge thyristor data books contain real good tutorials on scr and triac applications that are not found elsewhere for example in summary read read read that s how you ll know what to design in which parts to use and how to solve the intractable problem that your boss has presented you with it helps to have a prodigous memory for details here here 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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tektronix scope for sale tektronix scope for sale mhz bandwidth portable not one of the xx series boatanchors delayed sweep works fine i don t have the manual they are available from various places no probes shipping email me for more info regards keith keith kanoun wa q kdk radio nl nuwc navy mil
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sci.electronics
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microstrip help wanted i need information on microstrip circuit design especially filter design for the ghz range can you recommend any good books journals or microstrip circuit design software all help appreciated gerry corley ece department univesity of limerick ireland
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sci.electronics
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re wanted a to d hardware for a pc in article apr doug cae wisc edu kolstad cae wisc edu joel kolstad writes in ncr mpd ftcollinsco ncr com brad wright writes if you know much about pc s ibm comp you might try the joystick port though i haven t tried this myself i ve been told that the port i believe that the a d converters found on a joystick port are really timers that tick off how long it takes an r c circuit the r being your paddle to charge up to something like vcc for games this works pretty well but you certainly wouldn t want to try to take lab measurements off something as non linear as that the best info i have seen so far is the article joystick metrics measuring physical properties through the pc s joystick port by michael covington in the may issue of pc tech journal it talks about how to read all kinds of things voltage current resistance in basic and even includes code for a simple oscilloscope display it s possible to read the joystick port directly if you don t want to use basic the detailed information for this is in the pc technical reference under options and adapters you have to provide some millisecond resolution timing functions but that s a subject which has appeared many times in articles from dr dobb s circuit cellar ink etc look for the public domain ztimer package on wuarchive good luck dev palmer dpalmer mcnc org mcnc room p o box rtp nc fax
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sci.electronics
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peltier effect heat pumps i was having a look through a couple of components catalogues when i came across a range of peltier effect heat pumps intended for cooling components for those who have not heard of this effect you put a current through one of these devices and it pumps heat from one side to the other reverse the current and you reverse the effect i think a temperature difference can give you an emf as well anyway it struck me that you could make a nice cool hot box for picnics with one of these a power regulator a thermostat and a couple of heat sinks the biggest device can shift w with an efficiency of which ain t bad although it would flatten my car battery in about half an hour unfortunately the catalogue didn t list anything more than the basic specs as a heat pump i imagine that you would get a back emf as the temperature gradient across the device increases if so presumably its power decreases as the back emf increases until eventually we have a steady state with no current being consumed assuming no leakage if so then the final temperature difference between the two sides could be set by the supply voltage and nothing more although that would be a lousy way to control it what i would like to know is are the above guesses correct what is the open circuit thermal resistance of a typical device i just want to be sure that my coolbox is not going to get warm too fast when i unplug it how does a peltier effect heat pump actually work it looks like magic why don t they use these things in domestic fridges freezers thanks in advance 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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sci.electronics
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re outdoor fm antennas in article beerb ccmail dayton saic com beerb ccmail dayton saic com bradlee beer writes i m interested in buying or building an omnidirectional antenna for the commercial fm band mhz the commonly sold ones are a folded dipole bent in an s shape and one with a pair of crossed dipoles i don t see either of these designs as exhibiting any gain and they probably aren t truely omnidirectional i m intrigued by the discone antenna does anyone have detailed information on how to design one for the fm band with ohm impedence is one commercially available are there other designs that have gain i already own a element fm yagi it works great but requires frequent rotation for those distant stations brad beer castle gate drive beavercreek oh brad for an antenna gain is synonymous with directionality the only way to get gain out of an antenna is to design in directionality the gain of an antenna is defined as the signal increase for a preferred direction over the signal obtained by an isotropic antenna bob sciamanda edinboro univ of pa
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sci.electronics
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re help with ultra long timing in article apr kuhub cc ukans edu wellison kuhub cc ukans e du writes i have a project that was drooped in my lap that is somewhat a pain to design what i am looking for is a stable ultra long solid state timer what they want to do is to place this thing on the antartic ice shelf and measure the amount of snow fall over a period of six weeks every two weeks they want to trip a selonoid to discharge different colored pellets by gas pressure out across the snow then by digging down into the snow the snow fall amount can be measured as they come to the different color pellets the problem is trying to build a timer that would stand the cold degrees and a power source that wouldn t drain i have looked at the xr timers and the standard ne dual timers but thier temp specs won t go that low also two weeks equates to seconds per firing which means one big timing cap i have found farad yes farad caps that have a working voltage of volts and are small in size but again the time of discharge at or lower degrees isn t linear i was thinking of using several timers chained together to fire the selonid at the end of the timing period but that blasted cold and the drain on a battery over six weeks is the pain one possibility would be to use solar panels but this is during the six month twilight anyone have any good ideas thanks in advance wes just a suggestion take a motorola mc b set it up to give you a pulse once every sec or ten secs with either a rc or xtal clock input then feed to a mc b as clock input and decode output for sec output might have to add a few and gates or decoder chips to get output and reset pulse back to the to restart cycle trigger a oneshot from the decoded riseing edge the one shot then goes to a mosfet to drive the mechanism to fire the pellet launcher these ckts require uamps of current between volts so a volt gel cell of a few amphours would last the six weeks then take the ckt board battery wrap in or of foam or build a box of out of the stuff with plywood or metal exterior build a small heater out of watt resistors in series to keep the battery and ckts warm nd thought use batteries one for heater one for timer and pellet trigger insolate insolate even though the chips state that the al rated devices are good to c the batteries have a considerable reduction in capacity oh make sure the area inside has minium air leakage hope this helps rw is this to long winded for the net be gentle
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sci.electronics
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re all electronics press and peel pcb transfer i think there is a huge difference in the materials and process for printer toner pcb s i get first time everytime results from a local hp postscript and hardly ever works from copies of the same artwork the printer results are so good that i have quit even looking for pc board processes if i had to use the copier version i would think i would look elsewhere the moral experiment and find what works toner transfer can give excellent results it like any process gives erratic results with variable inputs r g
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sci.electronics
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electric power line balls i got a question from my dad which i really can t answer and i d appreciate some net wisdom his question is about some diameter balls which are attached to electric power lines in his area he s seen up to a half dozen between two poles neither of us have any experience with electric power distribution my only guess was that they may be a capacitive device to equalize the inductance of the grid but why so many between two poles anyone know what they really are is there a related faq for this is there a better group to submit to we d both appreciate some enlightenment scott townsend sverdrup technology inc nasa lewis research center group fsset bach lerc nasa gov
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sci.electronics
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composite video what are hd and vd i ve got an rgb mistubishi monitor and on the back it has bnc connectors labeled like this composite hd vd sync red green blue i ve used it as a straight rgb monsitor but i can t figure out how to use it for composite could someone explain what these markings mean thanks for any help tom tom rodriguez jack cc gatech edu multimedia computing group gvu lab georgia institute of technology atlanta georgia
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sci.electronics
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re radar detector detectors nhowland matt ksu ksu edu neal patrick howland writes from what i understand about radar dectectors all they are is a passive device much like the radio in your car they work as an antenna picking up that radar signals that the radar gun sends out therefore there would be no way of detecting a radar detector any more than there would be of detecting whether some one had a radio in their car unfortunately you re wrong on both counts the most common method of implementing a tunable receiver is to have a local oscillator the local oscillator s frequency can be radiated out of the receiver via the antenna unless the circuit is designed and constructed with great care for a reference on detecting radios get the paperback book spy catcher the author discovered how to detect radio receivers from their local oscillator emissions back in the s while he worked for british intelligence greg greg andrews gerg netcom com fortune cookie radioactive cats have half lives
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re peltier effect heat pumps in article snap paj uk co gec mrc paul johnson writes i was having a look through a couple of components catalogues when i came across a range of peltier effect heat pumps intended for cooling components for those who have not heard of this effect you put a current through one of these devices and it pumps heat from one side to the other reverse the current and you reverse the effect i think a temperature difference can give you an emf as well anyway it struck me that you could make a nice cool hot box for picnics with one of these a power regulator a thermostat and a couple of heat sinks the biggest device can shift w with an efficiency of which ain t bad although it would flatten my car battery in about half an hour so called cool hot boxes have been advetised for several years i recall damark advertising them in a recent catalog problem with the units is they do a sh y job of keeping food cold warm the peliter devices used just don t seem to have enough punch to keep up if you want something hot you need to heat it up before you put it in the box and end up hours later with food thats only moderately warm same goes for cold items unfortunately the catalogue didn t list anything more than the basic specs as a heat pump i imagine that you would get a back emf as the temperature gradient across the device increases if so presumably its power decreases as the back emf increases until eventually we have a steady state with no current being consumed assuming no leakage if so then the final temperature difference between the two sides could be set by the supply voltage and nothing more although that would be a lousy way to control it what i would like to know is are the above guesses correct what is the open circuit thermal resistance of a typical device i just want to be sure that my coolbox is not going to get warm too fast when i unplug it you de probably be better off getting a good coleman tm cooler and stocking up on blue ice blocks how does a peltier effect heat pump actually work it looks like magic why don t they use these things in domestic fridges freezers same as above not enough punch in them to keep get things cold hot thanks in advance 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 mike behnke senior tech advisor quid est illuidin aqua fermi nat accel lab equipment suuport batavia il computing div pistrix pistrix behnke fnalf fnal gov my opinions are my own not of the lab so if you don t like them call uwh iner
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sci.electronics
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dimming incand lamps what s the latest and greatest way to dim incandescent lamps march circuit cellar has part one of an article about dimming vac lamps but it seems to lead into phase control as the best method for controlling brightness i ve always hated phase control for the rfi buzzing filaments and non linear adjustment range i had heard that you can modulate the ac line on a cycle by cycle basis to get better results to cut the lamp s power to you would givemsay cycles of ac then nothing for another cycles i wonder if anyone has tried this or knows what the pro stuff is using any advice is appreciated ken email sidhu bode ee ualberta ca
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sci.electronics
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low cost oscilloscopes i am looking at buying a low cost scope for general purpose use any recommendations is this info in a faq somewhere any pointers appreciated thanks gerard gerard talatinian network systems gtalatin ucs indiana edu university computing services fax indiana university voice
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sci.electronics
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seeking thermocouple amplifier circuit i would like to be able to amplify a voltage signal which is output from a thermocouple preferably by a factor of or so that the resulting voltage can be fed more easily into a personal computer based adc data acquisition card might anyone be able to point me to references to such circuits i have seen simple amplifier circuits before but i am not sure how well they work in practice in this case i d like something which will amplify sufficiently nicely to be used for thermocouples say a few degrees accuracy or better any pointers would be greatly appreciated
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sci.electronics
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re jacob s ladder hi all i ve been following this thread about jacob s ladder for a few weeks and i happened to come across one of the best project books that i ve seen in a while the book gadgeteer s goldmine by gordon mccomb offers over excellent low cost projects including jacob s ladder tesla coils plasma spheres a van de graaff generator robots an ir scope and several laser projects the instructions come with complete part lists warnings and diagrams for those of you who are interested in building any of the above listed projects you should seriously consider getting this book the paperback version is only too for those who want more information title gadgeteer s goldmine space age projects auth gordon mccomb pub tab books cw isbn x paperback price paperback scott scott a bailey include std disclaimer h ecl operator computer engineering i m just a knight who chases the moon university of rhode island haven t caught it yet but i haven t let that bailey vader egr uri edu keep me from still trying each day and night bailey ecl uri edu
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re what is zero db in article apr sei cmu edu rsd sei cmu edu richard s d ippolito writes in article pkveuinnduk gap caltech edu joseph chiu writes the ohmite company was the first to characterize resistances by numbers thus our use of the ohms yeah right and the company was started by george simon ohmite that s completely inaccurate the ohm was an original standard made equal to a the resistance of a standardized electric stove heating element that s where the song ohm on the range came from of course scott
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re police radar just how does it work the father of a friend of mine is a police officer in west virginia not only is his word as a skilled observer good in court but his skill as an observer has been tested to be more accurate than the radar gun in some cases no foolin he can guess a car s speed to within mph just by watching it blow by whether he s standing still or moving too yes how was this testing done and how many times calibrated speedometer it s not the some cases that worry me it s the other cases eg suboptimal viewing conditions even the best subjective viewer can only partial compensate for certain distortions and optical illusions
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sci.electronics
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re electric power line balls fsset bach lerc nasa gov scott townsend writes i got a question from my dad which i really can t answer and i d appreciate some net wisdom his question is about some diameter balls which are attached to electric power lines in his area he s seen up to a half dozen between two poles neither of us have any experience with electric power distribution my only guess was that they may be a capacitive device to equalize the inductance of the grid but why so many between two poles anyone know what they really are is there a related faq for this is there a better group to submit to we d both appreciate some enlightenment i think those are to make the lines more visible to airplanes and helicopters cheaper than blinking red lights course i could be wrong kris
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7,070 |
sci.electronics
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need manual for hp scope i have a hp scope that i think has a problem in the hv section symptom started turning on and off on its own making intermittant bright flashes on the crt and then finally passed away if you have a manual or any suggestions please send me mail will gladly pay reproduction shipping costs plus a little for your efforts for the manual thanks in advance jeff jeff depolo wn a twisted pair h w depolo eniac seas upenn edu rf mhz mhz ghz university of pennsylvania
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sci.electronics
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re what is zero db the ohmite company was the first to characterize resistances by numbers thus our use of the ohms i don t know about this one but it doesn t sound right damn right it doesn t ohm s come from the greek letter omega which is used for resistance impedance of course the original poster may have been being facetious let s hope so mark neidengard mneideng cosmos acs calpoly edu
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7,072 |
sci.electronics
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re few video questions in article hpfcso fc hp com myers hpfcso fc hp com bob myers writes situation sometimes called block sync you can generate such a combined or composite sync in two simple ways or the h and v syncs together which gives you the non serrated block sync or exor them which makes serrations try it actually the exor doesn t really do kosher serrated sync since it puts the rising and falling for that matter edge of the h sync pulse off by a pulse width but that usually makes no difference sometimes it depends on your monitor and your timing if you don t have enough vertical front porch and you use xor composite sync you can get even odd tearing at the top of the screen which is very sensitive to the hhold control it looks like what you would expect if you scanned the even fields say onto a sheet of mylar and had pinched the upper left corner with your fingers and started to tear it off the tube with proper composite sync equalizing pulses the interlace is rock solid ii cccccc jim cathey ii sssscc isc bunker ramo ii cc taf c spokane wa iissss cc uucp uunet isc br jimc jimc isc br isc br com ii cccccc one design to rule them all one design to find them one design to bring them all and in the darkness bind them in the land of mediocrity where the pc s lie
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7,073 |
sci.electronics
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videotext teletext descrambler hi i am looking for a pc card which does european videotext teletext descrambling pal does anyone in the us sell such a card i once saw an article about a card with the same functionallity in a european elektor magazine but i wasn t able to track it down thanx in advance dan
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sci.electronics
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re electric power line balls in article apr eagle lerc nasa gov fsset bach lerc nasa gov scott townsend wrote i got a question from my dad which i really can t answer and i d appreciate some net wisdom his question is about some diameter balls which are attached to electric power lines in his area he s seen up to a half dozen between two poles neither of us have any experience with electric power distribution my only guess was that they may be a capacitive device to equalize the inductance of the grid but why so many between two poles i ll bet there s a runway nearby jeff babb babb sciences sdsu edu babb ucssun sdsu edu programmer sdsu larc
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7,075 |
sci.electronics
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re conductive plastic what happened if you re thinking of reactive polymers they re making esd safe contau iners out of it as far as being conductive goes anything with a resistance less than to the fouth rth power ohms per cubic measure is classed as conductive per mil std for esd protection my us bob
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sci.electronics
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attn h wheaton ucal davis i tried to e mail you but the message bounced motorola has a university support program through which i ve been told folks at schools can get sample quantities of parts if you d like to try this route e mail me for the address phone i don t wish to post it for all the world to see dick young motorola inc who doesn t have a thing to do with my opinions they re my own fault
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sci.electronics
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re radar detector detectors in article pslckinnmn matt ksu ksu edu nhowland matt ksu ksu edu neal patrick howland writes from what i understand about radar dectectors all they are is a passive device much like the radio in your car they work as an antenna picking up that radar signals that the radar gun sends out therefore there would be no way of detecting a radar detector any more than there would be of detecting whether some one had a radio in their car from my rather rusty knowledge of radio most radio receivers use a superhet circuit so that the incoming signal is mixed with a local oscillator giving a fixed intermediate frequency if that is more easily amplified the detector detectors work by picking up if re radiated from your radar detector in britain where one has used to pay for a tv licence there are were tv detector vans prowling the streets looking for people who hadn t paid their licence fee they had a couple of long solenoid antennae on the roof and i believe could triangulate an operating tv from the if i wonder how much of the if is radiated back from the detector antenna and how much from the rest of the module it might be worth putting the detector in a proper rf shielded enclosure andrew daviel vancouver canada advax triumf ca finger advax reg triumf ca for pgp key
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sci.electronics
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re rumors in article apr cs unca edu kepley photon phys unca edu brad kepley writes i just heard an unbelievable rumor that motorola has decided to drop their integrated circuit manufacture business apparently a digikey rep called one of our production coordinators for out information so that we could make plans to deal with this that moto was getting out anybody else get a call about this too much for me it s about like intel announcing they were getting out of the ic business this rumor didn t happen to appear on april st if this digikey rep was serious i think i will buy my parts elsewhere if that is the way they do business you cannot trust them mark
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7,079 |
sci.electronics
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re electric power line balls do you know if there is an airport nearby they may just be markers to tell pilots of small planes that there are power lines nearby joe
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sci.electronics
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home made ir remote extender here s a question for all you electrical engineers out there i bought an infrared detector module at radio shack for it is a little gizmo that senses infrared remotes and produces an output signal then i hooked the output through a transistor to an infrared led the circuit works like a minature remote control extender in my car all remote commands are relayed to the cd player hidden in the glove compartment it works fine with my denon cd player but when i tried to build the same circuit for a friend s vcr it didn t work the circuit appears to work for other remotes you can see infrared with a sony ccd camcorder but coincidentally it only seems to work for my cd player any advice would be appreciated brian ubsiler msuvx memst edu
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7,081 |
sci.electronics
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holes practical questions was philosophical question in article sun scri fsu edu jac ds scri fsu edu jim carr writes i agree i come at this from nuclear physics where one often discusses particle hole excitations and certain reactions have the effect of applying an annihilation operator and creating a hole and it is a subtle question the longer one works with them the more real they become there are also quasi particles which raise the same sort of question about how real the entity is the phenomenon is most certainly a real one ok i ve asked this before and with a new thread on these lines i ask this again if a large hole current is run thru a resistor will there be i r cooling instead of heating can anyone design an amplifier that preferentially amplifies hole currents over normal electron currents what semiconductor materials have the highest ratio of hole mobility to electron mobility please quote actual test samples rather than estimates based on theory also don t be limited to semiconductors consider also insulators resistors dielectrics piezo electrics conductors magnets metal ceramic magnetostrictives etc notes to summarize this thread has so far stated that the only area where holes are not detectable is the vacuum that is hole particles only exist in the presence of matter previous threads have stated that holes only exist in certain semi conductors the question that naturally arises is if the hole currents inside a semi conductor vanish at the point where the semiconductor is joined to a conductor say copper i don t want a theoretical discussion here about whether holes could exist inside metal conductors rather i ask for an experimental discussion on how to amplify and detect such currents if they exist also note that i have cross posted this to sci electronics since this is now becoming an electronic discussion thanx eric et a force of nature
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sci.electronics
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re need tone decoder circuit in article hplsla hp com tomb hplsla hp com tom bruhns writes does anybody out there have a circuit that will decode a hz tone use a ne tone decoder pll chip my impression it s not an area i ve played with much is that the much beloved ne is basically obsolete if you want to detect a khz tone set a switched capacitor filter chip to that frequency feed your input to it and see if anything comes out the other end the ne was what you used when good clean bandpass filters were hard to do nowadays they re easy and the results are better all work is one man s work henry spencer u of toronto zoology kipling henry zoo toronto edu utzoo henry
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sci.electronics
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motorola mc and mc does anyone out there know of any products using motorola s neuron r chips mc or mc if so what are they and are they utilizing standard network variable types snvt ted van den heuvel heuvel neptune iex com kx p
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7,084 |
sci.electronics
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re electronic odometers was used bmw question the bmw speedo is triggered by a reed switch magnet assembly in the differential i would think that this signal would be easy to reproduce
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7,085 |
sci.electronics
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ibm pc xt switch settings 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 thankx jim
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7,086 |
sci.electronics
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re adcom cheap products in article mdonahue x amiganet chi il us mdonahue amiganet chi il us mike donahue writes as for adcoms mobil they are going with amps that canb use balanced inputs a very nice toy but i m afraid its goig to push their amps beyound resonable price ranges especialy because taking advantage of those balanced inputs requires a rca to balanced adapter umm when i was doing sound reinforcement for a living i used to get direct boxes which convert unbalanced jacks to balanced xlrs for about each or a little more for higher quality you ll need two for a stereo signal of course and a little adapter thingy from radio sh t to convert from rca to total cost should be around you can also buy transformers for quite a bit less and wire them yourself total cost there should be under you can get all this stuff from any pro music shop that sells sound reinforcement gear the benefit no noise that you can hear will be generated in the cables going to the component with the balanced inputs even when you run them in bad places like next to power lines john bell nasa langley research center bell hops larc nasa gov
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7,087 |
sci.electronics
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re telephone on hook off hok ok circuit tony kidson tony morgan demon co uk wrote in article ohzs b w w k qwb lonestar org lrk k qwb lonestar org writes mcovingt aisun ai uga edu michael covington writes in article ptolq p e werple apana org au petert zikzak apana org au peter 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 greggo greg moffatt moffatt bnr ca bell northern resarch inc ottawa canada my opinions not bnr s
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sci.electronics
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dumb question function generator i have a new scope and i thought i d save a few bucks by buying one with a function generator built in after having it awhile i noticed two things about the function generator for one there seems to be a bias even when the pull offset is pushed in that is i have to pull that know and adjust it to get a signal sans some random mv bias the other really annoying thing is that the damn output won t go below about v p p i am a student you may have guessed from my previous posts and i often have to measure the input impedances of various circuits i build many of the circuits have maximum input signals of way less than mv amplitude and most have input impedances in the s of kohm range the thing is in order to use my function generator i have to divide the voltage to some thing reasonable then of course to measurethe input impedance of my circuit i am going to have to throw in another resistor in series with the ohm output of the generator i could just ignore it but now with this little divider there i have to figure that in it s kind of a pain in the ass is there any way i could make myself a little box that could solve this little problem the box would tkae the function generator input lower the voltage and give an output impedance that is some low unchanging number i would want to lower the voltage by a factor of one hundred or so i could just build a little buffer amp but i d like to have this box not be active any quick ideas the scope s not broken for other reasons i had sent it to the shop to get repaired and they replaced it the function generator was the same way on that one too please help as i am feeling very stupid today dave dgj y virginia edu
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7,089 |
sci.electronics
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can i use a cd analog multiplexer for digital signals as the subject says can i use a for digital signals i don t see why it couldn t handle digital signals but i could be wrong anyone have any advice thanks i i raymond yeung internet nimbus uiuc edu rky uxa cso uiuc edu ee student at the university of illinois compuserve at urbana champaign i i
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7,090 |
sci.electronics
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re emergency vehicle sensors traffic light phreaks in article linnig apr m dseg ti com linnig m dseg ti com mike linnig writes folks here in the dallas area i have noticed that it is quite common to see an odd sensor on top of traffic lights these have been here for at least six years i ve often wondered what they are mike linnig texas instruments inc of all statistics are made here in erie pa there is a system in the inner city called rado lite a trade name which allows police and ambulance vehicles to gain right of way by controlling traffic lights through radio signals the receivers look much like what you describe but they include a uhf whip antenna less than a foot tall and a light which flashes on and off to let traffic know that an emergency vehicle has taken control and is approaching local folklore says this system was invented here i don t know if this company has any other installations it has been in operation for at least years going only by my memory bob sciamanda edinboro univ of pa
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7,091 |
sci.electronics
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faq corrections greetings i received a reply stating that unless someone else confirms that the following company is operating i should remove it from my lst pcb prototypes of sandy ut ronald baker south east sandy ut tel read below this is from the comm pcb faq commercial pcb makers also i don t have time to get the faq onto the sci answers because of what i like to refer to is red tape after the finals i ll see what i can do in the mean time anyone know of an ftp site that wouldn t mind a k file and last i have some new entries for the simusoft list mostly commercial institutional stuff but was wondering should i keep the restrictions on the price of the software to be considered under or should i include all those in digit prices also 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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7,092 |
sci.electronics
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re illusion this is not a new idea at least years ago i got this little gadget with a keyboard on the back and led s in a vertical row on the front it has a long handle and when you wave it in the air it writes the message you typed on the keyboard in the air this is not news in fact it s where i got the idea from since it was such a neat item mattell made it i believe modeled after a space saber or light sword or something likewise theme y my addition was using a motor for continuous display and polar effects in addition to character graphics i should have protected it when i had the chance no one to kick but myself ten years ago is about right since i built mine in or
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7,093 |
sci.electronics
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re need help with car stereo just a shot here but ya never know i once bought a real cheap equalizer power amp for my car tape player at one of those motel room truckload sales and it sounded great for a while that is then one channel quit entirely i opened it up and the amplifier chip for the bad channel had simply melted some of its solder joints attaching it to the pcb i soldered them back and it worked fine i just had to keep the volume a bit lower than i did before probably lousy heat sinking you said a nice alpine which i m sure is a few orders of mag higher in quality than the p o s i had but the point is look inside before you scrap it since you occasionally find something you can repair maybe even the same thing i found good luck
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7,094 |
sci.electronics
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re uninterruptible power supply 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 just some ideas can t guarantee what ll work or not but hope at least some of this helped
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7,095 |
sci.electronics
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exploding tv 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 w my prasad prasadr vtvm cc vt edu
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sci.electronics
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re can microwaves be used to collect xyz coordinates 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
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7,097 |
sci.electronics
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low voltage lighting and x questions can low voltage lights be controlled with an x module by putting it before the transformer it seems to work even the dimmer works not very reliable will it damage the module can it be done reliably i put a motion switch heath to a low voltage light it worked but now it is broken too much current how can i get arround that how can i increase the intensity of a light using the x pc computer interface without having it go on first and then down i am doing my own programing not the x program thanks c montenegro
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7,098 |
sci.electronics
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re dumb question function generator in article c j b murdoch acc virginia edu dgj y kelvin seas virginia edu david glen jacobowitz writes i have a new scope and i thought i d save a few bucks by buying one with a function generator built in hmm now where was that ad for the combination radio hand cranked generator flashlight siren i saw function generator has a mv offset and the amplitude s too high is there any way i could make myself a little box that could solve this little problem the box would tkae the function generator input lower the voltage and give an output impedance that is some low unchanging number i would want to lower the voltage by a factor of one hundred or so i could just build a little buffer amp but i d like to have this box not be active sure you ve already got the right idea ignoring the ohm internal resistance of the generator for a second just run it into say a voltage divider made of ohms in series with ohms this new circuit is the thevenin equivalent of one that puts out of the original voltage and has an output impedence of negligibly less than ohms you may want to monkey with the values a little depending on whether you care more about the exact dividing ratio or the availability of parts hows that sound joel kolstad p s this is why those high voltage probes for multimeters can be accurate but still cheap they have something like megs in series with k which doesn t load the often high impedence source much as well as keeping the probably meg impedance multimeter happy
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7,099 |
sci.electronics
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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 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 wex
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