Mainly showing how low the frequency responce is... You can already see the phase shifting and much faster than 1hz it gets worse plus attenuation...
On Wed, Nov 25, 2020, 11:19 AM John Dammeyer <jo...@autoartisans.com> wrote: > Sam, > I'm not sure what the purpose of the 1 Hz sin wave modulation is. Why and > what are you trying to show with that? > John > > > > -----Original Message----- > > From: Sam Sokolik [mailto:samco...@gmail.com] > > Sent: November-24-20 8:21 PM > > To: Enhanced Machine Controller (EMC) > > Subject: [Emc-users] Interesting observations with a cheap bob's analog > out. > > > > Granted.. I know these are pretty basic. You can usually find them for > > under 10 dollars. They do work quite well though. I was working on > some > > youtube content and was goofing around with this bob and the printer > port. > > Setting up a pwmgen to test the analog out unearthed some things.. > > > > -It isn't very linear. lincurve is your friend.. It can be off by as > much > > as .5v over the range. > > -it is sloooowwwww. It is most likely a simple low pass. The photo here > > is of a 1khz pwm signal modulated by a 1hz (yes - hz) sin wave. You can > > already see it is phase shifting. 10hz and it is attenuated to about 2v > > p-p. > > -the pwm frequency didn't really affect the linearness or performance. > > > > http://electronicsam.com/images/greenmachine/IMG_20201124_183913.jpg > > > > one of these bobs... > > > > http://electronicsam.com/images/greenmachine/IMG_20201124_183919.jpg > > > > Still pretty cool what you can do with the printer port still ('I'm not > > dead yet!') and rt_preempt. (50us base thread) This could be why I > wasn't > > able to get a very tight spindle speed control on the little emco lathe. > > (I am using this bob's analog out driven from mesa pwm) And you are > > certainly not going to control an analog servo with it ;) > > > > sam > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
