I'm trying to hook up a 12V gearhead motor to a TIP120 being controlled by a PWM pin from the arduino. For some reason, when the pin is reading 255/ supplying a full 5 volts, only ~5 volts is going through to the motor from the 12V supply that I have the collector hooked up to.
I've confirmed that the PWM (controlled by potentiometer via an analog-in pin) is giving the full range of values from 0 to 255.
The motor does go full speed when it is just hooked up straight to the 12V power supply so it's not the motor. I've tried another TIP120 as well so it's not broken. The arduino is powered via usb from my computer.
Is there a reason the TIP120 would only be allowing less than half of the expected voltage through?
no, the motor is hooked up to the emitter, then to ground.
the collector is hooked up to the 12V source.
the arduino output is hooked up to the base.
I also put a diode between the emitter and collector but whether that was in or not didn't alter the results.
I'm doing this in a class. I went through the setup with my teacher a few times, and he says it's hooked up correctly, but i'll try to post a diagram later. any ideas until then? does anyone know why something like this could happen?
no, the motor is hooked up to the emitter, then to ground.
That's why it won't work.
Put the emitter to ground. Collector to motor, other end of motor to +12V. Arduino output pin through a resistor to the base. Diode from collector to +12v with cathode to the +12
