MaxHeadRoom
- Joined Jul 18, 2013
- 28,617
If you don't have a 12v supply of adequate current, stick it across an automotive battery, if it fails to run at ~3krpm and has considerable torque , then there is something wrong!
Max.
Max.
It doesn't run when connected directly to 12v.You mean you can connect 12V to it and it doesn't run?
Or that you've never connected it directly to 12V?
If not I suggest you try that.
Your clarification needs clarifying.
Sounds like your 12v supply in inadequate.It doesn't run when connected directly to 12v.
.
While the PWM does "work", the frequency bleed is a problem.
What frequency "bleed"? If you can hear the PWM you need to increase it's frequency to one that's out of hearing range.It runs well when I use a PWM circuit, but the PWM circuit is very noisy.
Why?I've experimented with changing values for R1 and C1.
That should give a PWM frequency of about 100kHz.If R1=100k and C1=47pf, the circuit was still quite audible at slower motor rotations.
470k to to large a resistance for that circuit.Changing R1 to 470k stops it from working altogether.
I was told here that ultrasonic PWM is the only way to drive a motor quietly enough to use with audio equipment.Why?
So now the goal post has been moved? Audio equipment is far different than human hearing. Most people can't hear PWM in a motor when the frequency is over around 16kHz. And most motor PWM circuits use 20kHz as a top number.I was told here that ultrasonic PWM is the only way to drive a motor quietly enough to use with audio equipment.
You might try a series inductor and capacitor to ground to smooth the current going to the motor.My suspicion is that anything with a square wave is going to cause some difficulty.