Re: Ignition coils as high voltage sources

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Ron Hubbard by way of Terry Fritz <twftesla-at-qwest-dot-net>" <hubbard_ron-at-hotmail-dot-com>




>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: Re: Ignition coils as high voltage sources
>Date: Thu, 30 Aug 2001 19:08:18 -0600
>
>Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-qwest-dot-net>" 
><evp-at-pacbell-dot-net>
>
>Tesla list wrote:
> >
> > Original poster: "Dan Olson by way of Terry Fritz <twftesla-at-qwest-dot-net>"
><dan__olson-at-hotmail-dot-com>
> >
> > I am in the beginning stages of building a smaller (under 100 watts 
>anyway)
> > CO2 laser, and I am having a bear of a time trying to find a neon sign
> > transformer to run the thing with.  I have heard of people using an HEI
> > ignition coil as a power source for these types of lasers, and being 
>that
> > you folks were the high voltage experts, I thought I would ask you how 
>well
> > such a thing would work.  The recomended power source for one of these
> > lasers is generally a neon sign transformer of about 15,000 volts by 60 
>mA,
> > but I have had no luck coming by one of those.  I do have a GM HEI coil
> > though, so I thought if I could get that to work, I would be set.  I 
>have
> > seen a couple of Tesla coils built around that coil, so if anyone would 
>have
> > a schematic or would be able to help me understand how to wire the thing 
>up,
> > I would be really appreciative.  I don't know a whole lot about 
>electronics
> > to be honest, although I have tinkered with them for a while now.  I am 
>very
> > well aware of the dangers of high voltage, and I will excercise extreme
> > caution when playing with this thing, so please don't feel skittish 
>about
> > helping me out.  I've done my fair share of high voltage work with oil
> > burner transformers, and I have learned how to conduct myself in it's
> > presence.  Ideally, I would like to run it either straight from a wall 
>plug
> > or else with a 12 volt battery.  I really don't want to have to build or 
>buy
> > a power supply if I don't have to.  Thanks a whole lot for any help you 
>can
> > provide me.
> >
> > _________________________________________________________________
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>
>	I think you'll be very disappointed if you try this.  The coils can put
>out a very few watts at best, and have quite high secondary inductance.
>Great for nice long sparks, but not for a high-power HV supply.
>
>Ed
>

I built a simple circuit using only three parts: an auto ignition coil, a 
2uF, 660 VAC cap, and a lamp dimmer. Connect one lead from the dimmer to one 
terminal of the cap; the other terminal to the positive (+) terminal on the 
ignition coil. The negative terminal is connected to the AC socket as is the 
other dimmer lead.

This works well, but there is no way to measure the voltage which is 
dependent on the value of the cap somewhat and the type of ignition coil. 
And my guess the current is no more than 20 or 30 ma. Might make for a nice 
Tesla coil if you could be sure to make the capacitors have a high enough 
breakdown voltage for the coil which could produce up to 40 kV.


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