They are actually rated from zero Hz (DC) to 100MHz. Ken
Kenneth Lerman 55 Main Street Newtown, CT 06470 On Mon, Oct 14, 2019 at 5:27 AM Gene Heskett <[email protected]> wrote: > On Sunday 13 October 2019 19:46:55 Kenneth Lerman wrote: > > > Hello All -- especially Gene, > > > > I've seen many posts on the lists regarding breakout boards and > > dealing with issues regarding slow opto-isolators. I have a question: > > > > Is anyone using: ISO776x > > <http://www.ti.com/lit/ds/symlink/iso7760.pdf> devices? > > I've seen that pdf before, but in the cases where I've simply bypassed > them, I had good solid, noise free sources to start with. If I use a > BoB, its a Saintsmart, simply because there is not any opto's in their > output path, and most outputs goto the input opto's of a stepper driver, > which I've found is a bit faster than the average bear. A 2M542 for > instance can, if the drive is good rail to rail stuff, be driven to > about 375k steps a second before it miss-behaves! That will turn a > nema-23 motor rated for 270 oz/in, to over 3000 rpms if the supply > voltage is pushing the 2M542 at around 42 volts. Nearly 2000 revs at 28 > volts. > > I suspect the reason they aren't used may have something to do with the > cost, or possibly the fact that they are capacitively coupled and very > low re-rate signals might drift back to their default state, without any > change in the input voltage. > > But thats, to me, just a SWAG. > > The most glaring example of too slow in my stuff is the 1000 line encoder > sitting on top of the G0704 spindle motor, an ABX encoder, and the > resultant "scale" is over 14,000 in the .ini file, and thats way too > fast for an opto. So I have 2, $2, rs485 convertors to make single > ended rail to rail logic out of the encoders differential outputs, Those > 2 single ended signals are now being fed to a sainsmart bob whose optos > I have bypassed, and on to the 5i25. Works perfectly. > > I have switches on the gearshift knob that tell my .hal file which gear > its in, or no gear in case its between gears, in which case I feed the > pid just enough offset to make the motor spin maybe 25 rpm when its out > of gear, making gear shifts slick and painless while its running! When > its in gear by the last degree and one of the switches is closed, the > circuit then scales the "scale" by the gear and restores the speed input > from lcnc, and 200ms later the spindle is back up to the set S speed > even if its 3000 revs. Thats 800 revs faster than OEM. > > The 5i25 encoders x input is still the x input from the original optical > encoder wheel I made. And with that high a resolution, quantization > noise is essentially gone, and I can run the spindle pid's PGain at 40 > or so, but 20 is unconditionally stable. > > With 126 volts in the motor supply feeding one of Jon's pwm-servo amps to > that 90 volt, 9.7 amp rated motor, I'm getting close to 2hp at the > amplifiers 17 amp limit, rigid tapping in steel with a 3/8's" tap can be > done by pecking in steel or cast, going about 1/2 turn per peck. No > change in the speed until that 17 amps limit makes its iron chirp. > > And I'm amazed that the plastic gears in that 2 speed head are still > working, by all rights I should have stripped the teeth off them by > now. Tough stuff. > > > They are 100 MHz data rate devices, have high isolation, have six in a > > package, and look like they would work just fine. The only downside > > might be that they are limited to 5.5 volts on the output, so you > > might need to add a transistor driver after them. And all of the ones > > in a single package share a ground. > > > > I hadn't seen them before, so I thought I'd mention them. > > > They look like they'd be perfectly usable in an active circuit, but I'd > have reservations about putting one in a home or limit switch circuit > until we find out what their dc characteristics are. > > > Regards, > > > > Ken > > > > Kenneth Lerman > > 55 Main Street > > Newtown, CT 06470 > > > > _______________________________________________ > > 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 > _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
