#garfield Logs

Feb 24 2023

08:09 AM rue_mohr: morning
08:19 AM rue_mohr: been looking at vga signals, kinda want to play with the CPLD and do video generation
08:19 AM rue_mohr: say, vga 640x480
08:19 AM rue_mohr: I did a logic capture, but only at 8MHz, looks like the pixel clock is 25MHz, not sure what the fake salee I have tops out at
08:19 AM rue_mohr: but I know if I push it there is funny signal lag
05:22 PM aandrew: hey Tom_L is there any issue with using scr-based dc motor speed control for a mill, or do I really have to find a 100VDC 1kW power supply and use PWM control?
05:23 PM aandrew: I'm thinking that the ripple will cause the speed to wobble but maybe it's not something relevant for this application
05:59 PM Tom_L: wouldn't be my first choice
05:59 PM aandrew: ok, so 120Hz torque ripple would be evident in the shaft speed I guess
05:59 PM Tom_L: may be a better rue question..
06:00 PM aandrew: I could take one of those SCR controllers and perma-set it for 90VDC output, feeding that into a PWM controller but I'd need some honking huge caps and they'd be very unhappy with the ripple
07:28 PM rue_mohr: unless the motor is getting to stalling speeds I dont think it would be noticable
07:41 PM aandrew: it's certainly a lot cheaper