On Thursday 30 November 2017 05:14:07 Les Newell wrote: > Hi Gene, > > Are you sure your maths is correct? > > > 1000*7161.17=761,170 line/rev > > So your drive ratio is 7161.17:1? At 3000rpm your encoder will be > spinning at 3000*7161.17. That's over 21 million RPM! > > Les
Yes, and its math I should have explored, but I had no clue that there was that big a geardown in the head, even in high gear, before I ordered that 1000 line encoder. That says the motor, running wide open, is turning about 20 k rpms. A 256 line encoder would have made more sense. Or even a 200 line, which is what I'd get using a teeny stepper as a generator. So I am going to make up a board to carry a 74ls86 today, which will be usable for either this encoder if I can crank up the sample rate some more, or for the stepper as a generator. 6 wire, 10k in series with each lead, with a paralleled 1n914 faceing each direction to protect the inputs of the ls86, then add a wee bit of hysteresis but not enough to desensitize at creep speeds. The encoders elastomer coupling should actually improve the creep speeds performance by responding to the slight cogging of the stepper, improving the velocity of the stepper at a transition. At 20,000 rpms, those R's are probably going to get hot, or be overvoltaged and arc fail. These motors, if I can remove the pulleys, have the same 5mm shaft the encoder does. So all I have to do is clean the single turn stops off the end of the stepper & pull the pulley. But I'll make the differential receiver first and then see if the 5i90 can handle it once its actually getting a square wave that actually looks like quadrature, the current situation is not quadrature by any definition. That has to be confusing the 5i25's decoder. Thanks for the sound board Les. Writing about it clarifies it in whats left of my mind. 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) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
