@IceChes (Isaac) posted a new topic, subject "WiFi slayer exciter". It read:

   Now that the robot is done, I want to start on the next project.
    
    Because the laser tag project will be pretty expensive, and because my last project was also quite expensive, I wanted to do something a bit cheaper in between.
    
    For a while now, I've been interested in high-voltage, so I popped onto the internet to do some research. Eventually I found an anecdote from a styropyro video which said that a slayer exciter is a great and relatively safe high-voltage project.
    
    After looking through way too many tutorials and articles on Hackaday and Instructables, and poking through one or two Plasma Channel videos, I created a rough CAD model and parts list.
    
    The basic concept is your traditional slayer exciter circuit, but it's controlled by an ESP32 running a web server and a relay, powered by a 24V 10A switching power supply. I calculated voltage output and found this:
    
    V = input voltage = 24  
    O = output voltage = ???  
    P = primary coil turns = 3-6  
    S = secondary coil turns = 1200
    
    V * (S/P) = O  
    24 * (1200/5) = 5760
    
    Output voltage is roughly 5760 at five primary coil turns.
    
    Anyways, I have a couple of questions.
    
      * What power supply do you recommend for a 24V, 10A switching PSU?
      * What kind of noise will the exciter generate? Will the WiFi control be unusable?
      * What risk do I have of severe burns?
      * What is the fire hazard posed by the exciter?
    
    
    
    Thanks in advance.
    
    EDIT - I know styropyro has a different threshold for "safe" than most people.

@aarg (aarg) replied

    5.8kV @ 200W. "What could possibly go wrong?"

After which, @IceChes (Isaac) added

    _From what I've heard_ the high frequency electricity only causes burns because of the skin effect. No idea if this is true.

After which, @Railroader (Railroader) added

    What is Your age, experience, education?  
    Reading Your questions I urge You to turn into something less dangerous. Get educated before taking on high voltage things. The project has the power to kill any human being.

So @IceChes (Isaac) replied

    I'm not experienced in the slightest. That's why I'm here.
    
    I do want to do something with high voltage, but if it's about to kill me maybe I'll look at something else instead

After which, @Railroader (Railroader) added

    IceChes:
    
    > From what I've heard
    
    Where did You "hear" that? Take a close look at commercial high voltage fences for cattle. They certainly don't use that kind of power.

Then @IceChes (Isaac) said

    Railroader:
    
    > Where did You "hear" that?
    
    I... forget. But I know I heard it. That said I don't know what kind of frequency the thing operates at. I don't have an oscilloscope so I wouldn't be able to measure it after building it either.
    
    So if it isn't high frequency, should I just throw a 555 timer on there to make it high frequency?

@aarg (aarg) replied

    Post #100 is mine.

To which @Railroader (Railroader) replied

    IceChes:
    
    > if it's about to kill me maybe I'll look at something else instead 
    
    Yes, please choose another project.
    
    Even as low voltage as 35 volt once killed a guy in a lab. Mains and higher voltage is deadly. You can create static electricity when doing Your hair and get high voltage but there's not 200 Watt available...

After which, @IceChes (Isaac) added

    Do you have any safe project suggestions?
    
    I still want it to be easy and cheap and preferably make light somehow. (Exciting gas tubes comes to mind).
    
    Railroader:
    
    > Even as low voltage as 35 volt once killed a guy in a lab.
    
    AC or DC?

So @aarg (aarg) replied

    IceChes:
    
    > Do you have any safe project suggestions?
    
    https://en.wikipedia.org/wiki/Kelvin_water_dropper

@IceChes (Isaac) replied

    Not gonna lie that's pretty cool.

So @Railroader (Railroader) replied

    The professor giving the university class didn't tell as I remeber. Does it make much difference?
    
    A musician was doing some work around the car battery. Somehow his arm was wet, likely from salt water. When he rested his lower arm across the poles of the battery his arm got badly burned! I saw him afterwards....  
    The salt made the water very conductive and a large current passed through the water and likely made it boil or explode....
    
    Some perspiration, what can that bring.....?

To which @IceChes (Isaac) replied

    Railroader:
    
    > car battery
    
    I know is is besides the point, but aren't car batteries like thousands of amps and only a few volts?
    
    Whatever. I see your point. Don't get close to dangerous power sources.
    
    EDIT - The school I go to has a fuse box in the garage which is where one of my classes is located. There are literally just transformers bolted to the wall with no covering. I don't know what would happen if you touched one of the coils, but I'd rather not find out.

Then @Railroader (Railroader) said

    12 volt and hundreds of amps available..... That can create heat..  
    A friend was tightening the bolt to the truck battery connector and used a too long swing with the wrench, and shorted the battery. The wrench exploded...
    
    To be an electrician and get old You work with one hand in the pocket..... A joke in that trade.

So @IceChes (Isaac) replied

    Hi.
    
    So is there some way I could get a slightly more impressive spark jump? Could I use a small capacitor bank for example?
    
    EDIT - Obviously high-voltage capacitors. Anything else would explode.

Then @ruilviana (RV mineirin) said

    IceChes:
    
    > Output voltage is roughly 5760 at five primary coil turns.
    
    Hi @IceChes  
    Electricity is a lot of fun.  
    What kills then?
    
      1. The electric current circulating through the heart;
      2. Fall from shock when shocked;
      3. High grade burns;  
    etc etc.
    
    
    
    If it's dry and you get a 127V AC shock between your thumb and pinky finger of the same hand, you'll get scared, but you won't die.  
    Since you have dry skin, the current is relatively small.  
    If you're wet and you get a 127 V AC shock between the thumb of your right hand and the thumb of your left hand, you're in for a big chance of dying.  
    As you have wet skin, the current is high.  
    What changes:  
    In the first case the low current will circulate between the two fingers of your hand and will not affect your heart current.  
    Ah, your heart works with electrocoque pulses, not the same as the Arduino, but similar.  
    In the second case, the high current passing from one hand to the other will also pass through the heart, and then RIP.
    
    A car battery has no potential to cause a large current through the heart, but if the circuit is small, like the hand and elbow of the same arm and the skin is wet with salt water, then the current can be high and provoke burn.  
    If you have a voltage of 5.8KV providing 200W,  
    and you zoom in (no need to touch), you can become a human torch. (If you are going to do this project, leave the filmmaker in automatic that I want to watch the video).
    
    I = E/R ...... W = E*I. Think aboult.
    
    RV mineirin

@IceChes (Isaac) replied

    The only thing I got out of this was one word.
    
    Gloves. I should wear gloves.

Then @IceChes (Isaac) said

    Did some research. Apparently a slayer exciter is not dangerous in the slightest.
    
    Source 1  
    Source 2  
    Source 3

After which, @Paul_B (Paul__B) added

    IceChes:
    
    > Did some research. Apparently a slayer exciter is not dangerous in the slightest.
    
    Not so sure about that, clearly depends on the scale of the device.
    
    IceChes:
    
    > _From what I've heard_ the high frequency electricity only causes burns because of the skin effect.
    
    You mean it burns your skin? 
    
    IceChes:
    
    >   * What power supply do you recommend for a 24V, 10A switching PSU?
    > 
    
    
    240 Watts will certainly do a bit of damage. We mostly use between 20 and 30 W settings on the medical diathermy, up to 50 W for serious stuff.
    
    Railroader:
    
    > A musician was doing some work around the car battery. Somehow his arm was wet, likely from salt water. When he rested his lower arm across the poles of the battery his arm got badly burned! I saw him afterwards....  
    >  The salt made the water very conductive and a large current passed through the water and likely made it boil or explode....
    
    No, the burns were more likely chemical burns due to electrolysis of the salt - chlorine and sodium.
    
    Railroader:
    
    > The wrench exploded...
    
    I don't think it exploded. Arced and heated rapidly perhaps. Wedding rings are a danger for mechanics.
    
    (May be a danger for others as well. )
    
    IceChes:
    
    > So is there some way I could get a slightly more impressive spark jump? Could I use a small capacitor bank for example?
    
    Certainly would make an arc more impressive but capacitors store only **DC**. So - much more dangerous.

After which, @IceChes (Isaac) added

    Paul_B:
    
    > 240 Watts will certainly do a bit of damage. We mostly use between 20 and 30 W settings on the medical diathermy, up to 50 W for serious stuff.
    
    Thanks for answering some questions. Should I use less volts? I was going off of the 30V power supply that a more high-powered one I found had.

So @Paul_KD7HB (Paul_KD7HB) replied

    IceChes:
    
    > So is there some way I could get a slightly more impressive spark jump? Could I use a small capacitor bank for example?
    
    Try a glass rod rubbed on your cat! Many thousands of volts.  
    Paul

So @IceChes (Isaac) replied

    Touching a doorknob and getting a shock is 4-10 thousand volts.

After which, @aarg (aarg) added

    For about 200 nanoseconds. So the total energy is not close to what could harm you. Also it's an "open circuit" connection, your body is insulated and so the spark current is just treating your body as a very small value capacitor.

So @aarg (aarg) replied

    IceChes:
    
    > Should I use less volts? I was going off of the 30V power supply that a more high-powered one I found had.
    
    This sounds like a change of tune from reply #5. There, it sounded like you had wisely abandoned the idea.

@IceChes (Isaac) replied

    I want to attain roughly the power shown in this article/video:
    
    Hackaday – 21 Mar 20
    
    ### Compact Slayer Exciter For Your High Voltage Needs
    
    Tesla coils are incredible pieces of hardware, but they can be tricky to build. Between the spark gap, capacitors, and finely tuned coils, it's not exactly a beginners project. Luckily, there…
    
    27V at 3A was used here. Maybe I should just power it off of those USB rechargeable 9V batteries?

Then @aarg (aarg) said

    Got a spare $2 in loose change?:  
    https://www.aliexpress.com/item/1005002483526260.html  
    Then you can play around with high voltage without necessarily killing someone.
    
    Doesn't "slay" mean kill? So a "slayer" is something that kills? Just saying...

After which, @IceChes (Isaac) added

    That's...
    
    Just a slayer exciter. Maybe with a couple more components added for compactness.

After which, @aarg (aarg) added

    I always heard it called, a "Tesla coil". But giving ordinary circuits creative names could be fun. I think I'll call resistors, "vampire toothpicks" from now on.

After which, @IceChes (Isaac) added

    A tesla coil and slayer exciter are two different things. Tesla coils have a transformer in their drive circuit and will KILL YOU. Slayer exciters have a very simple schematic. No transformer or spark gap, just a transistor.
    
    aarg:
    
    > I think I'll call resistors, "vampire toothpicks" from now on.
    
    I think I'm going to call diodes "policemen".

To which @Paul_B (Paul__B) replied

    aarg:
    
    > Got a spare $2 in loose change?:  
    >  https://www.aliexpress.com/item/1005002483526260.html   
    >  Then you can play around with high voltage without necessarily killing someone.
    
    The kit is sitting around here somewhere, just _waiting_ to be assembled (and frankly, it is not the only one ). Hmmm, perhaps when I sort out the washing machine I will have a go at it!

@IceChes (Isaac) replied

    Screenshot 2021-10-02 8.29.47 PM674×538 39.3 KB
    
      
    Reddit seems to disagree on the dangers.
    
    Posted in reddit.com/r/highvoltage

Then @IceChes (Isaac) said

    I just bought one. Along with a replacement for an RF nano I torched. Check out my post about my 1lb combat robot.

So @er_name_not_found (Oh say can uC?) replied

    IceChes:
    
    > Reddit seems to di
    
    Stopped reading at Reddit

To which @IceChes (Isaac) replied

    Heh. Reddit has the dumbest and smartest people at the same time. I'll just see what kind of info I get elsewhere, maybe on a more specialized forum specifically for high-voltage projects.
    
    Oh, I also got this. Seems to know what he was talking about.
    
    Screenshot 2021-10-02 11.48.50 PM664×576 74.9 KB
    
    About the first part, in the post I mentioned that it ran on 10A, and the respondant mistook that for the output power. _MY GOD_ that would be dangerous.
    
    Anyways but from what I found, yes it can be dangerous. But only if I build it to be.

@aarg (aarg) replied

    IceChes:
    
    > Slayer exciters have a very simple schematic. No transformer or spark gap, just a transistor.
    
    REALLY!!!????

So @IceChes (Isaac) replied

    

So @aarg (aarg) replied

    Well, what do you think L1 and L2 are? NM, it's a transformer. It's also a transmitter that will blitz radios for several blocks. Not sure if I should have told you that.
    
    By the way, we're now on reply #38 of a thread concerning a relatively simple question. Has it been answered? What have you done?

@IceChes (Isaac) replied

    Yeah it's a transformer.
    
    aarg:
    
    > blitz radios for several blocks
    
    Who listens to the radio anyways?
    
    And yeah, I have answered pretty much everything.
    
      * 9V batteries
      * Yes.
      * Low.
      * Low.
    
    
    
    EDIT - Unfortunately I don't have an oscilloscope so I can't figure out what kind of signals would break under the influence of the device.

After which, @aarg (aarg) added

    IceChes:
    
    > Who listens to the radio anyways?
    
    That is a really bad attitude. Anyone who uses wireless devices too, just because they're digital doesn't mean they are immune to interference. Just more resistant.
    
    Again, as this thread is dragging on, what is the question or problem, exactly? Has it been answered/solved, if not, why not?

@IceChes (Isaac) replied

    True. I might want to build a faraday cage.
    
    Then again some people report signals being totally fine, so I guess there's only one way to find out. Thanks for the help!

So @aarg (aarg) replied

    I have a spectrum display on my radio so I can see all the interference from the consumer and commercial junk around my location. Usually it doesn't bother me, but there are a few sources that really make it hard to use.
    
    The international regulations concerning RFI emissions partly protects the extremely valuable resource of the RF spectrum from careless or unintentional abuse. Athough there are no specific regulations covering science experiments, there is an assumption of "good faith" and an understanding of the effects, that would guide a "common sense" avoidance of interference with existing spectrum users.

Then @IceChes (Isaac) said

    So basically you are telling me to get an old ATX power supply and put the thing inside the case to block interference?
    
    Oh, and I can get some free voltage regulators and diodes and crap.

Then @aarg (aarg) said

    We're on reply #43 now and it feels more like a chat room, than a help topic. Please provide a list of specific questions that are aimed at solving some specific problem.
    
    I don't care what "you can do". I want to know "what you are doing" or "what you have done".
    
    At the moment, it appears that you are requesting information about how to build a device that you are clearly unqualified to work with, for safety reasons. This would be the second time, the first time you wanted to play with high powered invisible lasers. Nothing has changed.

@IceChes (Isaac) replied

    No, I'm pretty much done. I'll just have to break out a radio to see how unusable signals become after putting it together (I bought one off Aliexpress to test before I make my own).

After which, @aarg (aarg) added

    IceChes:
    
    > before I make my own
    
    It really does seem like you're fishing for information about how to make it more powerful. That is the problem.

Then @IceChes (Isaac) said

    Eh, not really. I just want to have one that I built rather than just buying one.
    
    Working on my combat robot I learned that there is such thing as too powerful.

To which @aarg (aarg) replied

    Can you mark this thread as "solved" then?

After which, @IceChes (Isaac) added

    Already did.

To which @Paul_B (Paul__B) replied

    IceChes:
    
    > Unfortunately I don't have an oscilloscope so I can't figure out what kind of signals would break under the influence of the device.
    
    An oscilloscope will not tell you **anything** about radio frequency radiation. A Spectrum Analyser would.
    
    aarg:
    
    > Anyone who uses wireless devices too, just because they're digital doesn't mean they are immune to interference. Just more resistant.
    
    WiFi is not going to be affected - it is way beyond the frequency response of the transistor in question.
    
    Except for the sparks, this device will not be "broadband", just a few harmonics of its primary frequency - whatever that is and which will likely move around a bit when you play with it.
    
    And it only has an antenna to the extent that you connect things to the output. Note the inverse square law.
    
    IceChes:
    
    > True. I might want to build a Faraday cage.
    
    Remember that **everything** including whatever bits and pieces you draw sparks to - and yourself if you are holding things - must be inside the Faraday cage. Not sure **you** will fit in an ATX casing.

To which @IceChes (Isaac) replied

    Paul_B:
    
    > Not sure **you** will fit in an ATX casing
    
    Shrink ray confirmed?
    
    Paul_B:
    
    > An oscilloscope will not tell you **anything** about radio frequency radiation. A Spectrum Analyser would.
    
    Or just a radio, no? Flip it on and see what channels are broken.

So @Paul_B (Paul__B) replied

    IceChes:
    
    > Or just a radio, no? Flip it on and see what channels are broken.
    
    A spectrum analyser is a radio that _automatically_ tunes itself across the **whole** relevant radio band.

After which, @system (system) added

    This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.


{'source': 'discourse', 'url': 'https://forum.arduino.cc/t/wifi-slayer-exciter/910834', 'title': 'WiFi slayer exciter', 'views': 1704, 'has_accepted_answer': True, 'word_count': 3108, 'like_count': 2, 'reply_count': 47, 'participant_count': 7, 'posts': 53, 'tags': '', 'author': '@IceChes (Isaac)', 'participants': '@IceChes (Isaac), @aarg (aarg), @Railroader (Railroader), @ruilviana (RV mineirin), @Paul_B (Paul__B), @Paul_KD7HB (Paul_KD7HB), @er_name_not_found (Oh say can uC?), @system (system)', 'image_url': [None], 'created_at': '2021-10-01T17:01:35.363Z', 'last_posted_at': '2022-04-02T21:42:51.329Z'}