On Monday 24 December 2018 08:21:57 John Hasler wrote: > Gene writes: > > In a cnc machine running on stepper motors, the current regulating > > of the drivers if the grounding is not truly single point, can > > crosstalk at the regulating frequency, usually well above 20 > > kilohertz, at peak voltages well over what it takes to destroy an > > fpga gate as the ringing in that event often peaks at over 100 MHz > > and 30 > > volts. Trivial to see on the samplers display, but turn off the room > > lights and really study what you see on a 100+ megahertz analogue > > scope. > > For that sort of thing you want a storage scope. Old Nicolets are > readily available for prices that even I can almost justify. > > I used Tektronix analog storage scopes when doing motor control design > in the seventies but the digital ones are orders of magnitude better. > Being able to trigger on things that already happened is cool. > > Before that it was cameras. > > As to TDRs, if you can get by without actually seeing pictures of all > the impedence bumps you can get by with a fast counter, a high > risetime pulse generator, and a couple of fast comparators. Maybe $20 > at Digikey.
I dunno if I could tolerate losing the pix, this old f--- has had a scope probe in one hand since 1951. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene>
