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
