Non Linear Wave Shaping - Clamppers

Prior to the Lab session:

1. Study the operation and working principle of Clamper circuits
2. Study the Classification of clamper circuits and its operation with positive reference, negative reference and zero reference voltages.
3. Study the procedure for conducting the experiment in the lab.

Objectives:

To study the various clamping circuits and to plot the output waveforms for a sinusoidal input of given peak amplitude.(Choose f = 1kHz, Vp-p = 10V).

Apparatus:

1. CRO (Dual Channel 0 to 20 MHz)                   -                       1 No.
2. Signal Generator (1Hz to 1 MHz)                    -                       1 No.
3. Diode (lN4007)                                              -                       1 No.
4. Resistor (l00K)                                           -                       1 No.
5. Capacitor (0.lpF)                                           -                       1 No.
6. D.C Power Supply 0 – 30 V (dual)                  -                       1 No.
7. Connecting wires
8. Bread board

Theory:

The process where  sinusoidal signals are going to be altered by transmitting through a non-linear network is called non-linear wave shaping. Non-linear elements (like diodes) in combination with resistors and capacitors can function as clamping circuit.

Clamping circuits add a DC level to an AC signal. A clamper is also referred to as DC restorer or DC re-inserter. The Clampers clamp the given waveform either above or below the reference level, which are known as positive or negative clampers respectively.

Clamping circuits are classified as two types.

1. Negative Clampers
2. Positive Clampers

Procedure:

1. Connect the circuit as shown in the figure 3.1 below.
2. Apply a Sine wave of 10V P-P, 1KHz at the input  terminals with the help of Signal Generator.
3. Observe the I/P & O/P waveforms on CRO and plot the waveforms and mark the values with VR = 0V, 3V, etc.
4. Output is taken across the load RL.
5. Repeat the above steps for all clamping circuits ( fig 3.2 to fig 3.6) as shown.
6. Draw the waveforms, assuming the diode is practical.

Circuit diagrams:

Input Signal

Fig.3.1 Negative clamping with zero reference voltage

Fig.3.2 positive clamping with zero reference voltage

Fig.3.3 Negative clamping with Negative reference voltage

Fig.3.4 positive clamping positive reference voltage

Fig.3.5 Negative clamping with Positive reference voltage

Fig.3.6 Positive clamping with Negative reference voltage

Observations:

Inference:

The different types of clamping circuits are studied and observed the response for various combinations of VR, capacitors and diodes.

Viva Questions:

1. What are the applications of clamping circuits?
2. What is the synchronized clamping?
3. Explain the Principle of operation of Clampers.
4. What is clamping circuit theorem.
5. What is the function of capacitor in clamper circuit?
6. What are the effects of diode characteristics on the output of the Clamper?
7. If we interchange the diode and the capacitor in fig 1 above, how the circuit behaves?
8. What is floating output and grounded output for a DC power supply? If we use grounded output PS in the above circuits, what will happen?
9. Calculate the power dissipation in the Resistor for any one of the above circuits?
10. What is the difference between a clipper and a clamper?

Outcomes:

After finishing this experiment students are able to design different types of clamper circuits.