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Re: Small Neon Transformer??



Ted,
	The 'transformers' that you are describing are identical to
some "metal-halide lighting" ballasts that I have. They are 3.5" by
4.5" by 5.75". the secondary is twice the size of the primary and was
connected to a XX?uF 600VAC cap. The topology is identical. Check very
carefully under the plastic between the primary and secondary for a
magnetic shunt. If they are metal-halide ballast transformers they are
shunt limited, give about 600VAC out without the cap. Mine are rated
for 1kW. The primary is tapped for 110, 207, 220, 240, 270, and 440V.
I've not bothered to measure the resistance, the wire looks to be
about A.W.G. # 14.

I've used them for ballasting my pig. Given the magnetic shunt, I
shorted the secondary and used the resultant leakage inductance as a
ballast.

>Each is about the size of my fist and has 2 winding sections.  The secondary
>section appears about twice the size of the primary.  Both sections appear
>to be wound on a single long narrow stack of laminations which runs parallel
>to the length of the transformer, and "in the middle" of the transformer.
>Primary resistance readings are about 25 Ohms.
This seems rather high to me, for any power.
>
>DIFFERENCES:
>TRANSFORMER #1
>Secondary resistance reading is about 8K Ohms.  Does this seem normal??

My 15kV 60mA neon secondary measures ~6K.
>
>TRANSFORMER #2 
>Secondary resistance reading is about 50 Ohms.  Does this seem normal??
>
>Has a third/middle wire lead on the primary and also on the secondary, and
>these "extra" leads seem to be connected to each other, but not to the
>primary or secondary windings.  What's the purpose of these "extra" leads?
>
>At least one of these "extra" leads was originally connected to a 300V/2uF
>cap; could this be for power factor correction?
>
For a resonant ballast, for some kind of vapor lamp. Not quite right
for a large metal-halide "street lamp"; a smaller variant? I'm not
sure.
>

Cheers,

jim