# Recommend a high-voltage generator

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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
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## Re: Recommend a high-voltage generator

"Michael Bell"  wrote in message

Sounds like you need an electric fence generator - not quite 100kv but
fulfil the rest of the spec !

Failing that google Tesla generators

AWEM

## Re: Recommend a high-voltage generator

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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David Littlewood

## Re: Recommend a high-voltage generator

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

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## Re: Recommend a high-voltage generator

Michael Bell wrote:

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

## Re: Recommend a high-voltage generator

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

## Re: Recommend a high-voltage generator

On 06/02/2012 12:51, Michael Bell wrote:
snipped

to be on the safe

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

## Re: Recommend a high-voltage generator

"Michael Bell"  wrote

Neon sign transformer and voltage multiplier with a separate inverter for
12V operation.

## Re: Recommend a high-voltage generator

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

## Re: Recommend a high-voltage generator

On 02/06/12 17:36, Pete wrote:

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