Would using a computer sound card and an audio recording software as an oscilloscope be a good idea?
If one is working and you've taken all the precautions to quiet things down, try one more motor. For now, you can run both off the same PWM line from the uC. If that works, go ahead and wire up all 4. You can still run them all off one PWM to keep firmware and hardware issues separate. If you have trouble remember that in addition to more potential noise from the additional motors, power supply and grounding issues will be magnified due to the higher currents involved.After going though all the info that you have provided...I tried the circuit with a few mods and its working satisfactorily...seems all it needed was twisting the motor wires...and a orienting the RF module away from power lines...but...will this circuit work if I use 4 motors? I mean..does 4 motors mean 4x the noise? What other modifications should I think of? Please help!!!