Jon Elson wrote:
Bob Engelhardt wrote:
I bought a servo amp on eBay ...

I think this is the same as a Copley 412, their setup and install data
may be more understandable and complete.

Thanks - even if it's not the same amp, the Copley instructions could
help my basic understanding.

You will need a DC tach. The motor can have some velocity ripple, the
tach MUST NOT! So, you do need to use an ironless rotor tach. The best
deal is to find a Maxon motor (These are tiny, about 1.25" diameter)
with silver brushes. They sell the same design as a tach. A number of
surplus dealers have them, or look on eBay.

Ah - good to know! Is any Maxon motor OK, or is there something in
particular to look for? I suppose if it says "ironless rotor", I'm set.
But, if not ...?

You will be able to hook a
10-turn pot to either the -10 or +10 V supply with a switch (for
direction) and signal ground, and the wiper of the pot to +ref in.
ground -ref in. Set it up for tach mode as shown in the chart. I think
you want to ground both +inhibit and -inhibit, and put a run-stop switch
on inhibit that grounds it to run. (You could also set up the direction
switch to be center off for the stop setting.)

Damn, it's going to be fun playing with this. 'Just have to wait out
UPS delivery from CA (to Mass.)

Thanks,
Bob

--
Nota for President