Experiment till you find a frequency that the motors like, and your ears like ;-). Also, even a small fan will help with the heat, especially if you can, as someone mentioned, solder some copper to the heat sink pins. If your board already has them connected to a healthy ground plane, then just cool the board with a little fan to get the heat away. Does it get too hot to touch? How long does it take to heat up? Neil On 10/15/05, Kevin wrote: > On Sat, 15 Oct 2005, Neil Baylis wrote: > > > Well, it sounds to me like you're on the right track. Why not just > > start using the PWM.? The 754410 should work fine in that mode. > > Exactly how hot is it getting now? Were you thinking of using a > > current sense resistor to control the current through the motor, or > > were you just going to run the PWM open loop? > > > > Neil > > > Well, someone calculated 4.2 W and the chip is spec'd at > 2.1 W, so pretty damn hot :). I already had the boards > made :( so I will try a good heatsink and OPEN Loop PWM. > I will try running in a 50% duty cycle any suggetions on > freq ? Should I keep it high >20Khz, so the motors don't > chatter, or should I use a LOW freq like 200 Hz ? > > Thanks, > Kevin > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > > -- http://www.pixpopuli.com -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist