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Registered Member #518
Joined: Tue Feb 13 2007, 05:20AM
Location: New York
Posts: 168
I found a YouTube video of a hand held EMP / RF device...
Based on the video, I was able to create a schematic...
Please check to see if I did it right.
Here are my coils. I laser cut plexy glass and glued the pieces together. I deviated from the schematic slightly, instead of 24 AWG, I used 18 AWG... Will this make any difference?
Registered Member #4074
Joined: Mon Aug 29 2011, 06:58AM
Location: Australia
Posts: 335
I haven't watched the video yet, but its a basic LC circuit similar to the primary side of a spark-gap Tesla coil.
The capacitor is charged from the HV source, until the potential is high enough to trigger the gap. Then the energy rings back and forth through the coil, producing a RF waveform that decays to zero over a few cycles.
Varying the capacitance or the construction of the coil will simply vary the frequency the circuit oscillates/resonates at. You can use something like JavaTC to calculate the frequency if you'd like, just fill out the relevant fields for the primary circuit. I'm currently typing on my phone, but later I'll try and remember to post the math for easily finding the resonant frequency of an LC circuit (this took way too long to type).
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141
the 'emp circuit' is as described above, so a 'better' capacitor, spark gap etc. will help but the greatest effects will be noticed when the 'emp' frequency matches tuned circuits etc. in r.f. receivers ok for quick fun ... but illegal everywhere due to r.f.i.
Registered Member #518
Joined: Tue Feb 13 2007, 05:20AM
Location: New York
Posts: 168
I got the 7kV module that you have and will use it... last night my "400kV" supply came...
I tried to fry things with it. but no luck. When the gap shorts out it makes loud popping sounds, so I'm guessing there is either an output capacitor in it, or its a cascade with capacitors.
With voltages so high, I probably need a coil that has more turns. However this guy used 5 turns of wire and it worked...
Here is a different version of an EMP. This one works right off the power supply (supply has high internal capacitance) Coil = 10 Turns 18 AWG
Works for lighting an LED but doesn't crash a calculator...
Registered Member #11591
Joined: Wed Mar 20 2013, 08:20PM
Location: UK
Posts: 556
Now what you need is a slapper capacitor from amazing1.com, a low impedance coil and a adjustable spark gap to change the frequency / power. That calculator would never work again.
Registered Member #518
Joined: Tue Feb 13 2007, 05:20AM
Location: New York
Posts: 168
What is a slapper capacitor? What is the capacitance of it and the voltage max? The problem I have with this power supply is I don't know the voltage output...
They claim 400kV, but based on spark gap length, it looks like 30kV ???
edit1: My LED lights up at a max distance of 9 inches...
edit2: Looks like my calculator was hardened or something, I was able to fry other stuff...
edit3: Here is a design I built long time ago and it worked...
Don't feel like fine tuning it though...
edit4: [PULSED EMP]
I just tried using 5 turns instead of 10 ...
LED/COIL works now at 12" @ 5 turns... before it was 9" @ 10 turns
I am able to induce random signals in a calculator at around 3 inches....
I wonder if the power will increase with some capacitors... This is a non resonant version, so this might work well...
[RESONANT EMP]
In a resonant version the cap value has to be tuned...
I'm still waiting for my capacitors and 7kV supply to come. Will keep you updated.
Registered Member #54278
Joined: Sat Jan 17 2015, 04:42AM
Location: Amite, La.
Posts: 367
I bought some of those tiny 7kV modules from ebay (about $4) to, hopefully, charge high voltage caps. At first I got nothing, but after installing a low current high voltage diode in series with the PS output to the capacitor--seems the module is polarized enough that it won't work unless the diode is connected properly--it works After getting all this connected, I could charge one of those 250lb caps fully in a few minutes--800uF @ 4kV. I suggest a power adapter (>= 2A) for the 3VDC to power the module input.--I get almost 10mA HV-out with low low load. NOTE: these things need a load, otherwise will burn out from overvoltage. also when the cap is charged to the max power supply output it is like an open circuit and will overvolt the module--I never got 7kV out of any of these--more like 5-6kV. As for the 400kV modules, they ran hotter, drew more current, and the output was worse than the cooler 7kV units--at least for cap charging. The sparks did seem a bit more violent though. A series diode and parallel spark gap keep it safe. My opinion...can't be beat for the price/performance ratio. The LC EMP gen. is a perfect app--won't give too many Watts---about six max. DOES ANYONE KNOW WHAT THE INTERNAL CIRCUIT IS?? I SUSPECT CW MULTIPLIER.
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Tiny EMP
