 By using a voltage source and resistor, the clamper can be biased to bind the output voltage to a different value.The voltage supplied to the potentiometer will be equal to the offset from zero (assuming an ideal diode) in the case of either a positive or negative clamper (the clamper type will determine the direction of the offset).If a negative voltage is supplied to either positive or negative, the waveform will cross the x-axis and be bound to a value of this magnitude on the opposite side.