On Sat, Jun 16, 2018, 3:23 AM Gene Heskett <ghesk...@shentel.net> wrote:
> On Friday 15 June 2018 23:53:03 Chris Albertson wrote: > > > On Fri, Jun 15, 2018 at 7:58 PM Gene Heskett <ghesk...@shentel.net> > wrote: > > > On Friday 15 June 2018 20:20:20 jeremy youngs wrote: > > > > > > Aerotech mentions > > > using 741's (op-amps) but the gain of a 741 above 10 hz falls like a > > > rock, and that leaves the nyquist phase v stability angles in doubt. > > > > If the paper suggests using a 741, then the paper is very old. > > That amazed me too, Chris. I was reading about 1960 technology. > > That pdf is from aerotech's own site, anybody can download it and read > it. Were I to design a similar device today, I'd certainly use lf357's > If I do this will I have to balance the op amp or is it a simple replacement? And check any electrolytic caps for old age, replacing as > necessary. > > Offtopic sorta: > > > > < > https://www.banggood.com/Transistor-Tester-ESR-Capacitance-Meter-Resistance-Inductance-Measuring-p-1044840.html?rmmds=search > > > > I have one of these and a variable supply for reforming caps, built a few > months ago to resurrect my wife's organ . > > If Jeremy got those used, they are probably takeouts from a 30 yo or > older machine. > 1993, pulled from working environment, I agree the 741 is ancient , and will likely replace them and will test these caps. The power supplies were worth what I gave for the drives. > > If you can, the simplest way is to connect the digital > > encoder to the mesa card, let it keep the position count then use that > > any way you wish, possible to create the analog output you want > I'm hoping to allow the mess card to do this and set torque mode to use the 4020 as a simple amplifier. Thanks for the reassurance this is a good idea. > > > By using pdm/pwm in the pwmgens. At 50 kilohertz, then integrating that > to get your analog voltage. But no not pass the raw signal thru an > opto-isolator, the control linearity will be destroyed. There are no > such critters in the 7i90/7i42TA control, but there will be in common > BoB's used with the 5i25's and such parport simulators. > > > I would not build an analog, op amp based digital rate the analog > > output converter even with modern op amps. That is not the best > > solution in 2018. A digital counter is the way to do. It is easy to > > make and as exact as you want. But I think the existing FPGA based > > hardware should be able to count and you'd not need to actually build > > anything. > > I hope to avoid building. I'm really busy in the auto shop so it will be a > week or two before theory hits action. > Indeed. Its all in the .hal code today, no "parts" involved. I think > what I would do is hook into the power supply's, disconnecting the old > active stuff and use them to feed power to one of the pico systems > pwm-servo's per axis controlled. This is a high probability, as mentioned the power supplies were worth the cost of admission. The control bandwidth is fast enough > that with a low resolution encoder. > The cui encoder is selectable, o have it at 1000 ppr as that's what the optical encoder that still works on the other ametek is at , that and 2.3:1 timing belt drive should give great resolution. I have the work flow to purchase x axis balkscrews in the near future as well. When I get a chance I'm going to get some photos of the recent goodies that have showed up. Thanks for bouncing ideas guys. ------------------------------------------------------------------------------ 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 Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
