I think the cheap 298 devices on eBay would work for you. They are 2-channel h-bridge. They actually have 6 inputs; forward, reverse, and enable for each channel. They will turn a motor from a single PWM signal, either via the enable input with one direction pin high, one low, or via a direction input with enable high and opposite direction low.
> On Oct 22, 2019, at 1:07 PM, Gene Heskett <[email protected]> wrote: > > Greetings all; > > Now I have to figure out how to drive then slowly. > > It seems like the obvious way is to set up a pwm driver running fast > enough to not make too much noise, and maybe even take advantage of my > carehart notches in my hearing by picking the rep rate to be 4 khz which > I can't hear at all. I can get that out of a 7i76 interface, probably at > logic levels or at field power levels. I fact I thought of driveing it > direct, but the running at 12 volts FLA is around 425 ma, and thats a > bit much, and would need a fast flywheel diode to protect the 7i76 from > the turnoff spikes. > > Searching for brushed motor drivers on fleabay, the choices are quite > limited. Most of the low priced L298 based drivers which could handle > two of these motors, also need 4 inputs, I assume to be mutually > exclusive so as to prevent crossover shorts in the L298. So the signal > drive timing requirements pretty much rule out the L298 things as I need > to use a single signal per motor driven. And that doesn't leave much > else because the vendors aren't listing the specs so one can make a > semi-intelligent purchase. Perhaps they don't even know what they are > selling, IDK. > > Suggestions for something cheap to drive a 12 volt motor labeled as > drawing 5 watts would be appreciated. > > I've even considered a power switch type fet (which I have a couple of in > to-202 formats) with a freewheeling diode to dump the shutoff pulse back > into the psu. I could whack out a pcb for that in an hour or so. I have > already the 12 volt field power supply at more than enough current in > the interface box. That would need a big bypass on the psu to protect > the 7i76 though. > > Which way should I go? Make it or buy it, if buy it, what do I buy? > > Thanks everybody. > > 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 > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
