GET out your trusty ohmmeter and measure it before you make a fool of
yourself.
It is a single coil of wire with a tap.
Call it what you will it is NOT two coils of wire insulated from each
other == transformer
wrote:
Actually, it is not a transformer.
It is ONE coil of wire connected across the AC supply with a variable
tap. Output is tied between tap and (Hopefully) neutral of the AC
input.
I think you should read up on autotransformers. Variac is a trade name
for a variable autotransformer, and they are in fact transformers. The
output of most of them can be adjusted *above* the incoming line
voltage, standard is about 10%. The one I have sitting here accepts 120V
input and outputs 0-140V so it is clearly a transformer.
For a bit more detailed info on the subject here's an article.
http://en.wikipedia.org/wiki/Variac