On Wed, 16 Sep 2020 11:09:47 +0100, Graeme
wrote:

In message , T i m
writes

Turn the 'Coarse' voltage knob down from 12 to 5V, or as near as you
can get with that control. If required, turn the 'Fine' voltage
control to get a more accurate value.

For my fairly basic use, I just leave both the fine controls and the
amps at maximum, and use the coarse volts knob for control.

Ah, that makes sense for the current (compared with leaving the fine
current control in the middle), as it's a 'upper limit' and assuming
you may need the full output etc.

The huge
advantage is the digital readout which shows both volts and amps
simultaneously, which is important for older motors.

Understood. That said, if I was doing that same job with my Weir PSU's
with a single meter is I would set the voltage to something suitable,
say 12V and then switch it over to current and could then watch the
meter.

Only if I reached full current would the voltage drop.

Just one example
is pre war permanent magnet motors. The magnets tend to degrade over
time, and consume more and more amps for the same performance, which
leads to overheating and damage to motor windings.

Ahh.

Watching amps
consumed, and knowing the usual usage, is therefore important.

Understood. I was doing the exact same thing when testing the Arduino
based MR automated project with BIL [1].

We were both amazed at the differences in current pulled by his older
and newer locos.

Because there was no speed feedback in the project and the vast range
of speeds resulting from said motor efficiencies, rather than going
for the choice of running 'any' of his numerous locos, we selected a
sub-set that all had similar power requirements.

I can't think of any role where the noise from the PSU would be an
issue to me or the controls too coarse. (And I have used what looks
outwardly to be an identical model for a range of power and electronic
things and found it fine).

Cheers, T i m

[1] I actually still have our MR automation test rig here. 4m of
straight track with a bypass section in the middle. 4 digital IR
reflective sensors positioned by the track near the ends and a diode
connected 'dead' section each end of the track to prevent overruns.

Loco, pulls away from end (with inertia) to max speed (adjustable with
pot) to the 1st remote sensor then slows (with inertia) to a creep
speed to the second sensor when it stops.

The two points are set (using bridge drivers and a cap) and loco
drives back the other way and round the bypass and back onto the main
line, to the remote sensors. And it actually works. ;-)