In article ,
(DoN. Nichols) wrote:

According to Joseph Gwinn :
In article ,
(DoN. Nichols) wrote:

[ ... ]

Agreed. I think that my isolation transformer is Triad, and
IIRC it has a rotary switch to make adjustments to the output voltage to
test equipment at slight over-voltage, and slight under-voltage.

I haven't seen that. Does Triad still exist?

Sure. They have a web site which does not work properly with
Opera on a Sun workstation, but here is the URL:

http://www.triadmagnetics.com/Catalog/index.html

Mouser carries a lot of their transformers, but they don't stock
the isolation transformers so I can't pull down any images to see how
they compare to mine. Mine is old enough so it has only a 2-pin jack,
and a "cheater-cord" socket for power to the transformer -- which would
match what you would expect to find in a TV repair shop anyway. :-)

Yeah. I have seen them. But I wonder if it's really Triad, or a front
for Chinese stuff only. I bought a 3-winding "Stancor" audio
transformer that claimed to be able to handle 1,000 volts between any
two windings, but when I measured the capacitance between windings, it
was a few nanofarads between two of them, and 100 picofarads between
those two and the other. Hmm. I bet the first two are bifilar wound,
and will handle only a few hundred volts, whatever the magnet wire
insulation can handle. The datasheet also gave bandwidth and
distortion, but failed to specify the power level at which this
distortion was achieved. I emailed Stancor, and got an incomprehensible
reply: they confounded DC resistance with power, although they did admit
that perhaps the 1,000 volts wasn't for all windings. I never got a
reply to my email asking for clarification of the unclear parts.

Joe Gwinn