On Wednesday 20 May 2020 00:03:37 John Dammeyer wrote: > > -----Original Message----- > > From: Gene Heskett [mailto:ghesk...@shentel.net] > > Sent: May-19-20 1:50 PM > > To: emc-users@lists.sourceforge.net > > Subject: Re: [Emc-users] hypothetical, maybe not, switching psu > > question > > > > On Tuesday 19 May 2020 15:44:51 John Dammeyer wrote: > > > Hi Gene, > > > Since I'm running DC Servos I wanted the ability to clamp the back > > > emf from a decelerating motor. I built a small circuit that > > > sensed both high voltage and AC power. It puts a resistor across > > > the DC rail to pull it down and the resistor is connected with > > > both a relay and a FET in parallel. > > > > > > When power vanishes the relay is de-energized and the 105VDC power > > > supply is quickly drained through the NC connection on the relay. > > > The FET does the same but at high speeds to avoid that over > > > voltage condition. > > > > > > Since the little PIC processor senses AC voltage it can also run a > > > relay on a second small board that switches across an inrush > > > resistor. The advantage over a high power thermistor is no heat > > > and you can cycle power without worrying about the inrush > > > thermistor still being way too hot and therefore too low a > > > resistance. > > > > > > Schematics attached. > > > > Both would seem to be more complex than a few lines of hal code I > > can easily write. > > Hey Gene, > That might be unless your PC dies or locks up. But even more > important, in my case I'm running dual boot and there is no HAL file > for MACH3. > I looked at MACH3 as it came with a demo copy for the 6040. Found it couldn't control the spindle at all, and went and got the computer and all the motor drivers stuff that was driving the teeny hf mill and hooked it up to the 6040's motors. All works, and about 190 ipm faster than the crap that came with it in that honking big box you see in the adverts. When I confronted the vendor about it he just shrugged.
Do not buy a 6040 without expecting to buy all new drivers folks. w/o them, it's worth maybe 800$, not the almost $1200 I paid. > Besides. I don't think safety critical stuff should depend on the PC. This is true. But its zero cost. And I'm aware of that safety stuff too. > John > > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users 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) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
