Re: High frequency impedance of a neon sign transformer

tesla-at-grendel.objinc-dot-com On Mon, 1 Apr 1996 09:00:51 +0700, you wrote:

>>From ed-at-alumni.caltech.edu Sat Mar 30 11:13 MST 1996
>From: ed-at-alumni.caltech.edu
>>Received: from alumni.caltech.edu (alumni.caltech.edu []) by uucp-1.csn-dot-net (8.6.12/8.6.12) with ESMTP id JAA14718 for <tesla-at-grendel.objinc-dot-com>; Sat, 30 Mar 1996 09:22:01 -0700
>Date: Sat, 30 Mar 1996 08:21:14 -0800
>To: tesla-at-grendel.objinc-dot-com
>Subject: Re: High frequency impedance of a neon sign transformer
[big snip]
> My assumption is that the transformer secondary
>input impedance should look capacitive above resonance (wherever
>that occurs, and I would think it would be pretty low with the
>high inductance and inter-winding capacitance).  Since your
>measurements appear to show otherwise I guess I will be forced

ditto at this end. I've been home with a cold today and the cold
medication has got me so wigged out that I actually cleaned the garage
before I was forced to!

> so I can put a
>transformer on it and make similar measurements before I comment
>	Subject is of current interest as I am looking into protective
>filters for the neon xformers, and trying to guess what will really
>happen with different configurations.  I am pretty sure that under
>some circumstances a typical L section LC filter may have transient
>response which will actually stress the transformer more than
>operation without it, but the approximations for transformer
>impedance at high frequency aren't good enough to trust.
>More later,
When I built my RFI filter, by just sheer bad luck I wound up with
values that resonated at the same frequency as my TC's primary. This
resulted in an increase of the 7.5Kv per side voltage to over 80Kv on
a spice model.  Of course, something, like the neon, would have blown
well before the voltage rise reached 80Kv! I put 2.25K ohms in series
with my RFI choke to dampen out any resonance.