[GreenKeys] Constant current selector magnet loop controller

[Jim Haynes]

By using a transistor in a constant-current connection it is possible
to get good loop signals with a lower supply voltage than the standard
120V 2000 ohm circuit.  Has anyone worked out what supply voltage is
sufficient with a constant-current circuit?

It's all probably irrelevant because what we get out of ITTY or some
other local sources are perfect signals, unaffected by the properties
of a long transmission line, so we don't have to accomodate some of
the things that matter in wire-line service.

But what prompted me to originate this message is an article in the
February 2017 issue of Electric Radio about using a part for constant
current reforming of electrolytic capacitors.  The part is
IXYS IXCP10M90S available from Mouser and others, and is described
as a switchable current regulator.  I haven't had time yet to study
the data sheet, but looks like this gives a constant-current circuit
just by choice of one external resistor.  And it's good for a supply
voltage up to 900V and an output current of up to 300ma.  One thing
I don't see mentioned is how fast it responds to being turned on and
off.

Has anyone on the list played with a device like this?

Jim W6JVE