10.4: Procedure

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10.4.1: Clipper

1. Consider the circuit of Figure 10.3.1 using Vin = 5 volts peak at 1 kHz, R = 10 k\(\Omega\), and both V1 and V2 set to 0 volts. For any positive signal over approximately 0.7 volts, D1 will turn on and limit the output voltage at Point A to 0.7 volts. A similar situation occurs with D2 and negative signals. A sine wave input over several volts will clipped at \(\pm\) 0.7 volts resulting in a squared off wave.

2. Build the circuit of Figure 10.3.1 using R = 10 k\(\Omega\), and both V1 and V2 set to 0 volts. Set Vin to a 5 volt peak sine at 1 kHz. Place one oscilloscope probe at the input and the second at Point A. Make sure the scope inputs are DC coupled. Record the positive and negative peak values of the resulting output waveform in Table 10.5.1. Also save an image of the scope showing both the input and output waveforms.

3. Set V1 to 2 VDC and V2 to 3 VDC, and repeat step 2.

10.4.2: Clamper

4. Consider the circuit of Figure 10.3.1 using Vin = 5 volts peak at 1 kHz, R = 100 k\(\Omega\) and C = 100 nF. Determine the input signal’s period and the RC time constant. Record these values in Table 10.5.2. For a large time constant, the capacitor voltage can be thought of as stable, basically a DC voltage. Initially, this voltage is zero. On the positive input half-wave, the diode is reverse biased and all of the signal drops across the resistor. On negative portions though, the diode is forward biased, limiting the output voltage to within one diode drop of ground. Also, the capacitor will begin to charge, eventually reaching the peak voltage of the input. This potential will add a DC offset to the input signal resulting in a clamped output.

5. Build the circuit of Figure 10.3.1 using R = 100 k\(\Omega\) and C = 100 nF. Set Vin to a 5 volt peak sine at 1 kHz. Set the scope inputs to DC coupled and apply the probes to the input and output points. Record the positive and negative peak values of the output waveform in Table 10.5.3.

6. Reverse the diode and repeat step 5.

10.4.3: Computer Simulation

7. Repeat the clamper procedure of steps 5 and 6 using a simulator, recording the results in Table 10.5.4.