please help me guys My inference to above circuit..... The negative cycle of the output signal from the driver is entirely clipped off before getting to switching transistor..this however don't have any effect on output because the transistor won't conduct for negative cycles but when due to any circumstance the reverse bias voltage on the base of the transistor increases the excess current would flow from emitter to base and then to ground via the diode thus protecting the transistor...am i right..? Does this circuit always sink current...? What would be the output when the diode is not present..? In order to make this circuit source current do i require a negative supply..?