On Sunday 26 May 2013 20:36:53 Steve Stallings did opine: > Gene, > > This board appears to use an LM358 bipolar op amp in its output > stage. This style of op amp will only swing the output voltage > up to about 1.5 volts below the supply voltage, so regardless > of the opto coupler performance you will not get 12 volts out > while running on a 12 volt supply. Indeed the output voltage > range claimed for the C41 is only 0 to 10 volts. It may go to > 12 volts out if powered by 15 volts assuming the output amplifier > is set up to allow a gain greater than one to be applied to the > filtered PWM signal. Keep in mind that the power source for this > board must be isolated from other supplies in the system because > it may be floating at line voltage depending on the motor driver > being used. > > Steve Stallings
I did some trace cutting and made the output stage a gain of 1.45 or so, so I am now getting about 10.4 volts, which helped some. Now it looks as if I may be forced to trade the 7812 in my home made supply in for a 7815 or an LM317?, whatever the adjustable one is. As for the isolation, that whole supply is isolated. Not from getting a buzz, but from ground. Its negative terminal is the zero speed terminal of the motor controller. The gain of 1.45 got me up to a hair over 400 revs in low gear, and about 925 in high gear. The 15 volt regulator should add another 50 to the low range, and about 100 to the high range. To do better than that, I'll need to change the countershaft pulley from a 3" down to the smallest that will fit the taperlock hub, 2.5" for sure, maybe a 2 but I've not checked on that yet. That will also need a shorter belt, and those are in Sioux Falls SD. Tomorrow I HAVE to mow this jungle, and Tuesday see if the shack has a 7815. Eventually I should have an independently controllable relay driver for reverse, then add a flipflop & timer to the .hal path to that pin. The flip flop is obvious, but the timer will be to lockout any change to the reverse signal until the dynamic load has brought the motor to a halt, saving CB trips etc in the controller should it try to change direction at 7k revs. I'll probably leave it using the 3" pulley unless I can see there's torque to throw away. There certainly wasn't any spare before once the work piece was above 3/4" in diameter if steel & that motor was a 400 watter. 2.5" alu was a chore that needed very sharp tooling and very light cuts, so this should improve that, a lot. So I'll mow tomorrow, see about a 7815 the next day, & then finish the swarf proof housing, stripping everything but the panic switch out of the front box. I have it all cut out of the side of a wrecked UPS van, 1/8" alu plate but need to place some alu angle brackets for the cover screws to tie it all together. I haven't checked the wiki, is there a CSS sample setup in there? If this still doesn't do it, you just sold another PMDX-106, without the OP panel. 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> If you try to please everyone, somebody is not going to like it. A pen in the hand of this president is far more dangerous than 200 million guns in the hands of law-abiding citizens. ------------------------------------------------------------------------------ Try New Relic Now & We'll Send You this Cool Shirt New Relic is the only SaaS-based application performance monitoring service that delivers powerful full stack analytics. Optimize and monitor your browser, app, & servers with just a few lines of code. Try New Relic and get this awesome Nerd Life shirt! http://p.sf.net/sfu/newrelic_d2d_may _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
