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Registered Member #2680
Joined: Wed Feb 10 2010, 09:23PM
Location:
Posts: 45
I built a simple marx generator that produces less than 100kV. Every time the marx generator fires (or misfires), the LCD displays displays nonsense numbers. I tried to increase the distance(to 1.5 meters) between the marx generator and the power supply and that made no difference. I put a TVS diode and a 0.1uF cap in parallel with the marx generator and the power supply, and also an inductor in series, but this made no difference. Is there anyway to fix this problem?
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Marxist (and Communists) tend to be harsh on digital meters with e-fields and M-fields. Yes I agree youll need a faraday cage out of screen-door screen or something similar. Remember its radiating these fields of interference everytime it strikes, so the usuall tricks for conduction interference dont work so well, TVS's, Caps. (at least with out the faraday cage)
Registered Member #2680
Joined: Wed Feb 10 2010, 09:23PM
Location:
Posts: 45
I never built a faraday cage before. Should the cage be grounded to the ground clip of the power supply or to earth ground? How small should the hole/mesh size be? What's the ballpark frequency of the radiation emitted?
Registered Member #1875
Joined: Sun Dec 21 2008, 06:36PM
Location:
Posts: 635
Dosinski wrote ...
I never built a faraday cage before. Should the cage be grounded to the ground clip of the power supply or to earth ground?
They should be the same... And if they aren't, I'd see to it that they are.
Dosinski wrote ...
How small should the hole/mesh size be?
Ideally you could just use a metal box or cover the enclosure with aluminum tape or foil to be safe.
Dosinski wrote ...
What's the ballpark frequency of the radiation emitted?
High. Your resonant circuit is composed of the series sum of your capacitors' capacitance and the stray inductance of your wiring and that of the spark gaps. So, high and not easily measured.
Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
ScotchTapeLord wrote ...
Dosinski wrote ...
What's the ballpark frequency of the radiation emitted?
High. Your resonant circuit is composed of the series sum of your capacitors' capacitance and the stray inductance of your wiring and that of the spark gaps. So, high and not easily measured.
Well it seems like the frequency wouldn't be too high to be measured by a DSO. Even an old 25MHz analog scope can measure a HF vttc which the resonator is much less than 10pf and 20 turns of wire. Im sure the inductance of his wiring and the capacitors would equal a few windings and the capacitance is likely to be over 100pf. But still, the voltage would make it hard to measure
Regardless, that would place the frequency in the MHz which sure would radiate plenty of energy.
Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061
I had a similar problem once with a calculator which failed when "flashed" from across a room with a commercial high power flash unit. This same unit would actually blister black plastic and disks at a range of 1cm (!) to the point that smoke was emitted.
Appears that the light hitting the inadequately shielded chip may have been responsible, as shielding it with cardboard removed the effect. -A
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