> My goal is to build a PS that's will be optimized for near-peak performance Is this a general purpose stepper driver you're designing? My understanding is that steppers are over-driven on their supply and then chopped to give a 'snappier' response but there are other issues to consider such as step-rate versus peak torque and also resonance in the drive train. I would suggest that choice of supply voltage is application dependant and is just one of several variables which may need tuning? I worked on a printer mechanism which ran 6V unipolar steppers with current limiting resistors and 12V bipolar steppers with chopper drivers all from a 24V supply, the motor manufacturer was SAIA. The steppers had something like 30:1 reduction gearboxes so we could play around with the parameters to get a smooth and quiet action. Our supply voltage was governed by a thermal print-head so the steppers were 'tuned' to work at that voltage. Something which caught me out was trying to step the bipolar motors too soon after enabling their power supply, it occasionally span them in reverse! Nigel Duckworth ----- Original Message ----- From: "PicDude" To: Sent: Monday, May 31, 2004 6:20 PM Subject: [EE:] Choosing stepper drive voltage Hi, I'm designing a stepper motor driver based on a PIC, but trying to figure out the best drive voltage to use for the steppers. My goal is to build a PS that's will be optimized for near-peak performance, yet not cause any damage, and trying to get a handle on if for example 10x vs 20x the motor's static voltage is going to make much of a difference. The motor is bipolar, with a rating of .23 ohms and 5.6 A in bipolar parallel mode. This gives a static voltage of 1.288 V. The driver circuit will be a chopper-type. I've seen recommendations of using anywhere from 4x to 25x the motor's static voltage, but trying to understand where these magic numbers come from. Also, this motor has a label with "Vs(dc): 35V" printed on it. Is this some indication of what voltage I should use? I expect the *best* voltage would be based partially on the frequency of the chopper pulses, and the rpm of the motor, but what else? Is there a more scientific way to choose my ideal voltage w/o just guessing? Thanks, -Neil. -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads