# Re: sign xformer parameters for a particular Tesla coil?

```Subject:  Re: sign xformer parameters for a particular Tesla coil?
Date:   Tue, 29 Apr 1997 08:51:08 -0400
From:   "Owen Lawrence" <owen-at-iosphere-dot-net>
To:   <tesla-at-pupman-dot-com>

>Subject:  Re: sign xformer parameters for a particular Tesla coil?
>  Date:   Mon, 28 Apr 1997 00:03:31 -0700
>  From:  "DR.RESONANCE" <DR.RESONANCE-at-next-wave-dot-net>
>    To:  "Tesla List" <tesla-at-pupman-dot-com>
>
>The basics go something like this:  You match the impedance of the neon
>xmfr with the impedance of the capacitor (capacitive reactance at 60
>HZ).
>A 30 ma xmfr matches to approx. a .005 MFD cap and a 60 ma xmfr matches
>approx. to a .01 MFD cap.  Step two is to match the resonant freq of the
>primary circuit (combination of cap and primary inductor) such that the
>resonant freq. will match the resonant freq. of the secondary inductor
>with
>HV terminal attached.  If all this sounds like Greek your best bet would
>be

In fact it doesn't sound like Greek, finally.  Here's what I think you
are
doing:

Capacitive Reactance Xc = 1 / (2pifC), and Impedance = Z = E / I

Equating Xc = Z and solving for C,

C = I / (2pifE) = .03A / ( 2 x 3.1415926 x 60Hz x 15000V)
= 5.305164860226e-9
= .005uF

Please correct me where I'm wrong.

I suppose things get more complicated (i.e. formula for
impedance
changes) when more components are added to the circuit, but at least I'm
in
the ballpark.

Yesterday I scored my first neon sign transformer!  I fully
functioning
15KV/30mA Alanson for the staggering sum of \$0.00!  The first two
companies
didn't have any, but the third guy didn't ask any questions; he just
happily reached under a bench, slammed this thing on the floor a few
times
to knock the dust off and gave it to me with a smile.  I promised him
I'd
bring in some pictures of sparks once I got it working and he said he'd
appreciate that.  I was making plasma arcs all evening!

Just one question: why do they give these things away when they
still
work?

- Owen -

owen-at-iosphere-dot-net
http://www.iosphere-dot-net/~owen

```