On Tuesday 11 June 2013 17:52:43 Gene Heskett did opine: Update of sorts.
I took a useless scale module out of the feedback path in my .hal, and put a 22uf cap in the d/a of the C41 where I'd pulled the OEM 10uf and put in a .2 uf thinking I needed the bandwidth. But as I was tuning things, I realized that my pwm-freq seemed to be working better at lower rates, but when I slowed it down to 240 hz, I could then hear that 240hz in the motor. More filtering with a 22uf there, and its now sitting at 120 hz, which seems to work well at the lower speed ranges, so up to about 360 rpms, and is more stable speed wise too. However, the speeds above 360 are still too fast. An S600 rpms, s/b 10 rps, as measured by my scope watching the index pulse, is about 740 actual, s700 is nearly 900, s800= about 1150, and s825 is a full 1200 actual. I can run that way I think, but I may yet put it in PDM mode, and make the charge pump driver & detector out of some 556's and the LM2907 plus something for a sample/hold. That, rather than the expanded scale I'm getting for 50% duty cycle and higher, will give me x millivolts output per cycle of the higher frequency pump signal, and hopefully much more linear control. Someone mentioned there being an RMS conversion as part of the existing PWM to analog conversion methods but don't recall who now, can someone suggest a link for reading that might get me some insight on this? Thanks. Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> is up! My views <http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml> I once heard Bill Gates say, "WHAT?!?! Netscape caused an invalid page fault!?! Only Microsoft programs have the code to do that!" A pen in the hand of this president is far more dangerous than 200 million guns in the hands of law-abiding citizens. ------------------------------------------------------------------------------ This SF.net email is sponsored by Windows: Build for Windows Store. http://p.sf.net/sfu/windows-dev2dev _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
