Re: [CAD_CAM_EDM_DRO] Re: 20 Amp 80 V $99 DC Servodrive

Mariss Freimanis wrote:

> You are right, I hadn't thought of that. You would want to introduce
> a much smaller transient than that. It is necessary though to elicit
> loop response in order to set compensation to critically damped or
> slightly underdamped. But use a MUCH smaller transient though.....

I managed to snag a Schlumberger Frequency response analyzer ($13,000
instrument) for $150 (plus a $50 VFD display to get it working again),
and
it injects a small current into the loop to excite a response, and then
reads
phase and magnitude of the result. At the lowest frequencies, it moves
the
machine 1/4" or so, at the higher end the machine hums.

Jon