[GreenKeys] Looking For Bits

[Jim Haynes]

I guess ideally you'd like less than a 1:1 transformer to get 120V for
the loop.  Like if you can find a spare M28 power supply, or even one
of the old boxes used with M15s.

However you can get 1:1 transformers.  One sitting on my desk for
future use is a Stancor GIS100  100VA.  Don't know if you can still
get Stancor.

You can get a Triad FD6-12 made in China from Mouser and other suppliers.
This is a transformer with dual primaries for 115/230 volt use; but with
plenty of iron in the core I use just one of the primaries and use the
other primary as a secondary.  And then it has some low voltage windings
that I use to run transistors circuits that drive the loop.  Which maybe
are not needed anymore now that we have optoisolators.