Most R/C servos have relatively small holding torque unless they have a steady pulse stream. Most are easily back-driven unless they are a high torque model where the higher gear ratio increases the holding torque. One can drop the refresh rate from 50 hz to something lower if power saving is an issue, although they really only draw power if the motor has to move. There is no 'braking' action by the controller. Only pulses from the H-bridge driver when there is a position error. And the controllers will respond to micro second wide pulse width changes so use a hardware PWM if you don't want a lot of 'chatter'. I doubt that R/C electronics have changed much since I designed the control electronics for C-leg prototypes a decade ago but YMMV. Robert Josh Koffman wrote: > This is just a guess, but I'm guessing it's assuming the gear torque > will keep it in place. From my understanding most of the servos are > fairly simple - a small DC motor with a gearbox and control/feedback > circuit. Adding an electrical brake seems like it would up the > complexity quite a bit. > > Again, just a theory, don't blame me if I'm wrong! > On 7/11/05, Luis Moreira wrote: >> On the R/C servos when you stop at a certain position do you rely on the >> high torque generated by the gears to keep the motor braked or does the >> controller inside the servo actually breaks the motor electrically? >> If it is the later do you guys have any info on it that you could share. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist