On Thursday 15 October 2020 18:20:08 Gene Heskett wrote: > On Thursday 15 October 2020 17:17:59 Thaddeus Waldner wrote: > > The reactance and inductance questions are above my pay grade and > > I’d be happy to hear someone explain it. :) I use these for robotics > > class in place of the old BJT L298, which are optimistically rated > > for 2 amps but have more than 2v drop at much less than that > > current. > > > > Maybe I don’t understand your comment but I’m pretty sure that a 50% > > duty cycle PWM waveform will run the motor at half-voltage. > > What I had in mind was a quicker than hal's logic can do it, as hals > direction reversal by controlling the inA and inB inputs will be > plenty slow enough to have it oscillate possibly uncontrollably. This > may not be the ideal device, we'll have to see once they arrive, which > could be as early as Monday. > > What I have in mind is basically a 400 watt or more, class D audio > amplifier. Maybe I've gone looking using the wrong search terms. Yes > and with very similar pricing, a dual 2kw is $25. I'm thinking...
So I've bought one of these too, and will see if I can somehow bypass the input coupling caps and make it run down to to DC. Or better yet, scaled to a 5 volt dc coupled pwm. > > You command the direction with INa and INb according to the Truth > > Table. The PWM signal will then switch either the A or B low-side > > FETs, depending on the INa/INb configuration. > > > > > It would appear that when enabled, and lets say with a pwm > > > frequency near the top of the 10khz range, that a 50% duty cycle > > > pwm waveform would be the equ of a balanced, at rest servo, so my > > > first question is how much additional inductance in series with > > > the motors leakage reactance will be needed to protect the chip > > > from the current surges at the pwm waveforms transition points? > > > > > > My hal file will obviously need to stage an initial enable at the > > > 50% duty points, then let the pid output thru. > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > Cheers, Gene Heskett 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
