I have this
DX H-bridge board, which seems to be an exact clone of this one
I was using it to switch an electromagnet and it works fine as long as I keep the EM away from other USB peripherals. If it's too near the peripherals pick up a lot of interference and stop working until I reconnect.
Now I'm trying to power a small "toy car" DC motor with it - the motor's been harvested a long time ago and has no datasheet or markings but it looks like a 3V motor.
I connected the three control pins to the arduino and used a pot to control speed (PWM < 127 on enable pin to avoid frying the motor) and direction. I'm using 2x16340 batteries for the motor power and USB for the arduino, with the grounds connected.
The interference is so high it's making the computer's USB malfunction even with the motor 1m away. After a couple seconds playing with the pot the serial monitor on the computer stops receiving data (the analog reading of the pot) and I have to reconnect to make it work again, can't even upload a sketch after it "crashes".
I stopped experimenting with this because I'm afraid it'll damage the computer.
Am I doing something wrong? Is there a problem with the H-bridge board or is this normal?