The Drive terminals are connected to a PWM signal generated by an arduino micro controller. The purpose of this circuit is to isolate the arduino from the motors to avoid too much current being drawn.
What I understand so far:
- The motor will only turn when the diode is reverse biased. When it is forward biased this will short circuit the motor and turn it off.
- The opto isolator (LED and NPN transistor) allows current to flow from the 6V rail toeards the -6V rail whenever the LED is turned on.
The rest confuses me. Can somebody please walk me through step by step how this circuit works?