[GreenKeys] About loop voltage

[Harold Hallikainen]

Mike, KD7VRG, pointed out that his MITE has an internal loop supply that
is only 26 volts instead of the more typical 100 volts or so.

So, of course, this got me thinking (always dangerous). Looking at, say, a
model 15, if it has pulling magnets, the coils are in series. With holding
magnets on a 60 mA loop, the coils are in parallel. This results in 1/2
half the number of turns (the fact that there are two windings in parallel
just makes it look like thicker wire since they are on the same core). So,
if we have half the turns, we have 1/4 the inductance. We can get the same
current rise time with 1/4 the voltage, which happens to be what the MITE
uses! Of course, if you add more machines in the loop, the inductance goes
back up again.

I have not looked inside my model 15 to see if it has pulling or holding
magnets. The Flesher TU-170 uses about 85V for the loop. Does a model 15
with  holding magnets with the coils in parallel work with 25 V (1/4 of
the typical 100 V)?

Harold
https://w6iwi.org