Experiment 2 Wave Shaping Circuits

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I. OBJECTIVE

To

To investigate investigate the the clipping clipping and and clamping clamping of of sinusoidasinusoidal l signal signal using using siliconsilicon diode.

diode.

II. BASIC CONCEPT

Diode can be used in wave-shaping circuit that limits a portion of a signal or Diode can be used in wave-shaping circuit that limits a portion of a signal or shift the dc voltage level. These are the diode clipper and the diode clamper are shift the dc voltage level. These are the diode clipper and the diode clamper are examples of wave-shaping circuit. The diode clipper prevents the output voltage examples of wave-shaping circuit. The diode clipper prevents the output voltage from exceeding a given value. It clips those portions of a signal that are above or from exceeding a given value. It clips those portions of a signal that are above or below the reference level. The

below the reference level. The diode clamper circuit shifts the entire waveform by diode clamper circuit shifts the entire waveform by aa dc level without

dc level without changing the original waveform.changing the original waveform.

III. MATERIALS

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1 1155--KKΩΩresistor (1/2 watt)resistor (1/2 watt) 2

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EXPERIMENT 2: WAVESHAPING CIRCUITS

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IV. WIRING DIAGRAMS

D1 1N4001 R1 15kΩ A B Ext Trig + + _ _ ₊ _ Function Generator 6V/200Hz Oscilloscope

Figure 2.1 Positive Clipper

R1 15kΩ A B Ext Trig + + _ _ ₊ _ Function Generator 6V/200Hz Oscilloscope D1 1N4001

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R1 15kΩ A B Ext Trig + + _ _ ₊ _ Function Generator 6V/200Hz Oscilloscope D1 1N4001 15 V 5kΩ

Figure 2.3 Positive Biased Clipper

R1 15kΩ A B Ext Trig + + _ _ ₊ _ Function Generator 6V/200Hz Oscilloscope 15 V 5kΩ D1 1N4001

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A B Ext Trig + + _ _ ₊ _ Function Generator 6V/200Hz Oscilloscope R1 10kΩ D1 1N4001 1uF

Figure 2.5 Clamper Circuit

V. PROCEDURE

A. DIODE CLIPPER

1. Connect the clipper circuit as shown in Figure 2.1. Set your oscilloscope to the following settings:

Channels 1 and 2: 1V/division, DC coupling Time Base: 1ms/Division

2. Connect the signal generator to the clipper circuit. Adjust the signal generator’s output at 6V peak-to-peak at a frequency of 200Hz. On the data page and results section, sketch your clipped waveform, showing the positive and negative peak values. Label properly.

3. Now reverse the polarity of the diode in the circuit as shown in the Figure 2.2. How does this waveform compare with that of step 2. Sketch your clipped waveform showing the positive and negative peak values.

4. Now connect the circuit of Figure 2.3. Apply power and adjust the potentiometer so that the DC voltage (VDC) is +1.5V. Connect the signal generator set at 6Vp-p.

What do you notice about the output of the clipper? On the data page and results section, sketch your clipped waveform showing the positive and negative peak values.

5. Vary the resistance of the potentiometer from one extreme to the other. What happens to the clipping level?

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6. Now reverse the polarities of both the diode and the DC power supply in the circuit as shown in Figure 2.4. Adjust the potentiometer so that the DC voltage (VDC)

is +1.5V. Connect the signal generator set at 6Vp-p. What do you notice about the output of the clipper? On the data page and results section, sketch your clipped waveform showing the positive and negative peak values.

7. Vary the resistance of the potentiometer from one extreme to the other. What happens to the clipping level?

B. DIODE CLAMPER

1. Connect the clamper circuit as shown in Figure 2.5. Set your oscilloscope to the following settings:

Channels 1 and 2: 2V/division, DC coupling Time Base: 0.2ms/Division

2. Connect the signal generator to the clamper circuit. Adjust the signal generator’s output level at 5V peak-to-peak at a frequency of 1KHz. You should see two sine waves. On the space provided at the data and results section, sketch the input and output waveforms, showing the positive and negative peak values for both.

3. Slowly increase the peak-to-peak input voltage and observe what happens.

4. Now reverse the polarity of the diode in Figure 2.5 and repeat steps 2, 3 and 4. Now what happens? On the space provided at the data and results section sketch both input and output waveforms showing the positive and the negative peak values for both.

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VI. DATA AND RESULTS

Table 2.1

CIRCUIT Vin(Vp-p) Vout(Vp-p) Measured Value Vout(Vp-p) Expected Value %Difference + Clipper -Clipper + Biased Clipper -Biased Clipper Clamper

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PEDROSO, ELVIN LOUIE R.

IX. ANALYSIS OF RESULTS

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XI. SELF-TEST QUESTIONS

1. For the positive clipper of Figure 2.1, the positive peak voltage is approximately a. 0V

b. +3V c. +0.6V d. +6V

2. For the negative clipper of Figure 2.2, the positive peak are not clipped because the diode is

a. Negative Biased b. Forward Biased

3. In all clipping circuits in this experiment, the 15-K Ω resistor is used to a. set the clipping level

b. set the peak output voltage

c. limit the voltage across the diode d. limit the forward current

4. For the circuit in Figure 2.3, the potentiometer is used to set the clipping level of the output’s

a. positive peaks b. negative peaks

c. positive and negative peaks

5. For the circuit in figure 2.4, the potentiometer is used to set the clipping level of the output’s

a. positive peaks b. negative peaks

c. positive and negative peaks

5. In the experiment, the rectifier circuit that has the greatest DC output voltage is the

a. half-wave rectifier

b. full-wave center-tapped rectifier c. full-wave bridge rectifier

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XII. APPLICATIONS (CIRCUIT SIMULATION)

1. Design a clamper to perform the function indicated by the figure below.

Ideal Diod es 30V 20 V (+ ) (+) Vi n V i Desi gn Vout 10V 20 V (-) (-)

2. Perform an analysis of the network on the given figure.

R 4.7kΩ Vo Si1 Si2 +20V Determine Vo and ID.