On 06/07/2010 10:09 PM, Ignoramus14096 wrote:
I found a DC power supply among the stuff that I had. This is a Syncor
PP-1659A/G military power supply called "battery charger". It is a multitap
transformer and a rectifier. Goes up to 150 volts and up to 20 amps.

I fixed up whatever physical damage it had (missing banana plug) and
now it seems to work well, except that on some settings it does not
seem to have good contact. Probably needs some multitap contacts
cleaned.

Anyway, I can set it to, say, 76 volts DC and just user it? Do I need
to put in any capacitors, since this is a pretty bare rectifier?

It may work great, but if you didn't remove any resistors from it you
may find that it has poor regulation under a varying load. Most battery
chargers need some sort of current limiting; you can do this in the
transformer by designing in a healthy amount of leakage inductance
(microwave oven power transformers usually have a slug of transformer
material wedged or spot-welded into the core between primary and
secondary for this purpose). So you may find that the transformer it
inherently incapable of good regulation.

And poor regulation to your servo amplifiers could cause all sorts of
weird problems.

I'd try it, but I wouldn't be surprised if it wasn't good enough.

And yes, put some filter caps in there.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com