# RE: Micro coil help

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From: 	Tesla List[SMTP:tesla-at-poodle.pupman-dot-com]
Sent: 	Friday, December 06, 1996 00.01
To: 	Tesla-list-subscribers-at-poodle.pupman-dot-com
Subject: 	Re: Micro coil help

> > Subject: Micro coil help
> Subject: RE: Micro coil help
> Subject: Re: Micro coil help
> > Subject: Micro coil help

>From bert.hickman-at-aquila-dot-com Thu Dec  5 22:45:58 1996
Date: Thu, 05 Dec 1996 06:53:59 -0800
From: Bert Hickman <bert.hickman-at-aquila-dot-com>
To: tesla-at-pupman-dot-com
Subject: Re: Micro coil help

<SNIP>

>Remove the cap. Its severely detuning the primary circuit, and also may
>not be able to withstand the higher voltage stress seen during Tesla
>Coil operation.

ok, I see now that you are correct, it does not make sense to have it there.

<SNIP>

>It looks like there's an error in your capacitance calculation - you
>appear to be off by roughly 6 orders of magnitude - the values you are
>predicting are about right if the units are PicoFarads (1e-12F) and not
>MicroFarads. The capacitance of a 2-plate capacitor can be approximated
>by:

>   A = plate area in square inches
>    k = dielectric constant (1 for air)
>    t = dielectric thickness (inches)

No wonder I was getting such weird results!!  I have that equation, but it said

>You need to determine if the transformer self-limits under short circuit
>conditions. My initial "guess" would be that it won't. The easiest way
>would be to place a 1000 ohm 10 Watt resistor directly across the output
>and measure the voltage developed across the resistor. If your
>transformer "limits" current to a relatively low value (say 10 MA), you
>should only see about 10 volts developed across the resistor. If you see
>substantially more, then you may need to externally limit current with a
>series inductor. Keep looking for that neon! :^)

Tried above setup, it does not self limit ( but it sure does get warm! :).
On a transformer like this one, what can I use as an inductor?  If I want
to use a resistive limiter, what resistance should I use?

Again, thanks for the input!
I dunno what I would do without it!
David Knaack
South Texas

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