On Tuesday 22 October 2019 23:21:19 Thaddeus Waldner wrote: > My own experience has been to use them as drivers for small SUMO cars > for a school robotics class that I teach. I wasn’t happy them them in > that application because they incurred a nearly 2-volt drop at 12v. > Though I didn’t mind students discovering that their drivers are > overheating and wondering why.
2 volts! Yikes! Thats bipolar and not being turned on near hard enough. They should at that point, take a detour and learn how to design a good power switch. > > The other application where I was surprised to find these is on a > Stratasys Dimension 3D printer as drivers for the extruder motors. > These extruders use tiny, lightweight dc motors with encoders and gear > reductions in lieu of the NEMA 17 found on nearly every printer. Of > course these printers are dinosaurs themselves, but this is why I > figured the drivers would work for other low power applications. I > agree that MOSFETS are a better option. > With a rail to rail logic drive meaning a 5 volt fwd bias when on, I doubt these IRF520's will lose 50 millivolts, negligable heat at .5 amps. I didn't figure 2 for 7 dollars was all that bad a deal. > Sent from my iPhone > > > On Oct 22, 2019, at 8:24 PM, Gene Heskett <[email protected]> > > wrote: > > > > On Tuesday 22 October 2019 19:31:59 Thaddeus Waldner wrote: > >> 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. > > > > That may be so, but indicates a smarter version of the L298 than I > > tried to use 20 some years ago, generating a pwm in a pc to drive it > > with then, and the thing I most remember is burning my fingers on > > the heat sink at 12 volts applied dc. The motor didn't fair much > > better, no current regulation resistor change made any diff. Fooled > > with it for about a week, made up my mind it would never find a home > > in any of my stuff. 3 of them acted exactly the same. And it hasn't. > > They went out with the trash. A year or so later I had bought the hf > > micro mill, and while looking for motor drivers found the 2M542, > > bought 5 of them so I'd have a spare. So far I have bought 9 of > > them, and nearly 20 years later, they are all working like new right > > now. Zero failures=no regrets. > > > > 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 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
