In the given circuit, the output becomes zero for vi less than -5 V. Hence, the peak value of the output is 25 V owing to the additive effect of V for vi.

Diode, Capacitor and Resistor are necessary to build a clamper circuit. An independent DC supply is required to bring an additional shift.

The circuit above is a parallel clipper. When the input is less than 4V, then diode is forward biased and thus output voltage is 4V. When input increases above 4V, the diode is reverse biased and output is equal to the input. Hence, minimum output is 4V.

The given circuit is a clamper with an independent DC supply of +10 V. Keeping in mind the connection of the diode and the DC supply, we see that the output waveform is clamped at +10V i.e. it shifts up by +10V. Hence, the maximum value of vo=+30 V.

Considering the connection of diode, it is evident that the diode becomes reverse biased when vi < -5 V. Hence, clipping starts at -5 V.

During the positive half cycle, the diode is forward biased and no signal appears across the output. The capacitor holds the charge in that state. During negative cycle, diode is reverse biased and diode does not conduct. The charge in capacitor is released and is obtained at the output.

In the given circuit, the diode is in the off stage when vi > 4 V. Hence, when vi > 4 V, vo = vi and hence the peak value of vo = the peak value of vi = 16 V.

The given circuit is a clipper that cuts off a part of the negative cycle of the input sinusoid i.e. the output becomes zero for a certain region of the input waveform. Hence, the minimum value is 0 V.

For the positive half of the input, the diode is in the on state and hence acts as a short circuit and hence vo = 0 V. For the negative half cycle, the resistor receives voltage input both from the source and the capacitor which is charged during the positive half of the input. Hence, vo = -20 V.

The circuit given above is a clipper. The diode conducts when it is forward biased, i.e, whenever the input vi is greater than 5V (for ideal diode). For lower voltages, the diode does not conduct and the output is zero.