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Re: 220V transformers on 120V?

Original poster: "Marry Krutsch by way of Terry Fritz <twftesla-at-qwest-dot-net>" <u236-at-earthlink-dot-net>

Hi Ian.

	Comments below


> A cap in series shifts it to be AC,
> but making a sine wave is harder... and I'm not sure the input
> to the transformer has to be sine anyway.

	If you're talking about a neon (or other 50/60 Hz xfmr), I don't think
a perfect sine wave is needed, although I think the transformer would be
happier with one (flybacks don't care what they're fed).  The leading
edge of the square wave should be rounded nicely by the primary
inductance of the neon.  The only problem I see is the sharp magnetic
field collapse (counter EMF???) when the tail of the square wave cuts
off.  This will cause a big voltage spike on the secondary of the neon
(maybe a few times the normal output voltage), which could cause
internal arcing (killing the xfmr).  If I'm wrong, hopefully someone
will correct me.

> I have a dozen or so small ones and have varied success in getting
> output from them.  I read that either high voltage or low voltage
> with a high frequency will do the same job, but I am not sure
> of why.  

	What kind of transformers are these?  (flybacks, 50/60 Hz, etc.)

> How does one figure out the proper power input into
> an unmarked transformer?  

	I have a method, but it sucks.  Hopefully someone else answers this
one! ;-)

> There has to be a good web page or
> book I can read to show me what I'm missing.  Thanks!


I don't remember whether or not transformers are discussed there, but
it's a great site for everything else electrical.  I've learned a bunch

Good Luck!


> --
> Ian Smith
> www.ian-dot-org
> www.sportsmogul-dot-com