I use Arduino Uno and Arduino Motor Shield R3 to control a 12V 1A motor from a printer. At default PWM frequencies, at slower speeds 90/255 it has quite low torque, but manages to do the job adequately (which is to swing a small bell). But at that PWM frequency it produces quite a lot of whine. So I decided to try increasing the pwm frequency. At 31kHz, it wasnt moving at all, neither at 15kHz. At 7.5kHz it could perform the task again, but that produces that awful whine again. At 15kHz, if I removed the load, I could see it slightly moving left and right. Obviously it lost almost all torque. Is there a way to use higher PWM frequency and keep the motor torque? Could it the be the shield? Maybe the motor?
Thank you for help!
Here is example at default frequency: https://www.dropbox.com/s/xgvf5kds5y53enl/11072013106.mp4