Recommend a high-voltage generator

Can you recommend a high-voltage generator, either to buy or to build myself. Specification:-
* Up to 100 KV * No need for heavy current, micro amps will do, it is supposed to be just for creating a field, but there is always leakage. * Light weight and robust * Powered by 12 volt battery parti
Michael Bell

"Michael Bell" wrote in message
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Sounds like you need an electric fence generator - not quite 100kv but fulfil the rest of the spec !
Failing that google Tesla generators
AWEM

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Alternatively, you could look at a voltage multiplier circuit - this is probably the simplest and cheapest way of obtaining kilovolts at microampere currents. I made one many years ago to power a laser (admittedly only several kV, not 100 kV) and it was quite simple and effective. See:
http://en.wikipedia.org/wiki/Voltage_multiplier
for an introduction.
David

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Thank you. Let's get down to nitty-gritty. I think 100 KV is probably the upper bound of what I want. I said that "just to be on the safe side".
* Am I justified in assuming at least 80% efficiency. So if the input is 12 V 1 Amp = 12 watts, at 50 KV I should get out 12 * .8 /50,000 0.2 MilliAmps? That should be more than enough.
* Can you recommend components?
Michael Bell

Michael Bell wrote:
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Not only will the components have to be rated at the right voltage, the physical construction will have to be very special indeed. Roughly, the breakdown voltage of dry air is about 30kV per centimetre So the hi voltage connections will have to be 4-5cm apart and away from any other surfaces. The old adage "It the volts that jolt and the mills (milliamps) that kills" is true but the jolt from 100kV won't do you any good at all.
I don't want to cause any offence, but to be honest this is one of those questions where if you have to ask how to do this, then you should possibly not be doing it.
If you are determined, I would certainly suggest you build a lower voltage one first and learn about some of the problems.
Measuring and characterising what you have built will also be non trivial and liable to kill test equipment without suitable precautions.
Bob

writes
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Ditto. In addition corona discharge will be a major problem. I built a 50KV multiplier diode tester for [a TV maker] and had to make all circuit nodes from large spheres to control it. http://www.rmcybernetics.com/science/high_voltage/voltage_mult.htm The job is much easier if you have a metal lathe to turn the shapes. http://electricwiringdiagram.com/wp-content/uploads/2011/06/cockroft-walton-generator.jpg
Suitable wire doesn't just have thick insulation, there is a semiconducting sheath around the copper to reduce the voltage field gradient.
jsw

On 06/02/2012 12:51, Michael Bell wrote: snipped
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I don't think this will be "on the safe side" of anything unless you are familiar with working with these voltages and take appropriate precautions. The tone of the question does not imply familiarity.
Sorry to be a bit harsh, but 100kV can be harsher

"Michael Bell" wrote
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Neon sign transformer and voltage multiplier with a separate inverter for 12V operation.

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I didn't think those things were of any use. I threw four oil-filled ones in the skip last year.

On 02/06/12 17:36, Pete wrote:
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A neon transformer is rated at several milliamps or more and a sure way to kill yourself unless you are familiar with hv technology and very, very carefull. One hand behind the back when making *any* live adjustments etc and don't work alone.
I tend to use Cockroft Walton multipliers to generate hi voltages. Start with as long as required, 1" wide glass epoxy base, with each diode and cap in a zig zag pattern along the length of the strip, using stake on vero pins or similar. Google C/W multiplier to see how it works etc. The nice thing about this method is that each diode and cap only need to withstand approx (Vout / number of stages) voltage, so you can use off the shelf silicon diodes and low cost polypropylene caps. Spray with silicon grease, dry, test, then perhaps encapsulate in your favourite hv compound...
Regards,
Chris