EXPERIMENT 3 Half-Wave and Full-Wave Rectification

Transcription

1 Name & Surname: ID: Date: EXPERIMENT 3 Half-Wave and Full-Wave Rectification Objective To calculate, compare, draw, and measure the DC output voltages of half-wave and full-wave rectifier circuits. Tools and Equipments Required DMM (Digital Multi Meter) DC Power Supply Function Generator 2.2 kω x 3 Silicon Diode x 4 Theory and Descriptions The primary function of half-wave and full-wave rectification systems is to establish a DC level from a sinusoidal input signal that has zero average (DC) level. The half-wave voltage signal of Fig.2.1, normally established by a network with a single diode, has an average or equivalent DC voltage level equal to 31.8% of the peak voltage V m. That is V dc = V peak volts (half-wave) eq.2.1 The full-wave rectifier signal of Fig.2.1 has twice the average or DC level of the halfwave signal, or 63.6% of the peak value V m. That is V dc = V peak volts (full-wave) eq.2.2 For large sinusoidal inputs (V m >> V T ) the forward-biased transition voltage V T of a diode can be ignored. However, for situations when the peak value of the sinusoidal signal is not that much greater than V T, V T can have a noticeable effect on V DC Figure 2.1 half- and full-wave rectified signal EEE 2116 Electronics I Lab. Page 1 of 8

2 In rectification systems the peak inverse voltage (PIV) must be considered carefully. The PIV voltage is the maximum reverse-bias voltage that a diode can handle before entering the Zener breakdown region. For typical single diode half-wave rectification systems, the required PIV level is equal to the peak value of the applied sinusoidal signal. For the four diodes full wave bridge rectification system, the required PIV level is again the peak value, but for a two diode center tapped configuration, it is twice the peak value of the applied signal. PROCEDURE PART 1. Threshold Voltage Choose one of the four silicon diodes and determine the threshold voltage, V T, using the diode-checking capability of the DMM. PART 2. Half-Wave Rectification V T = a) Construct the circuit of Fig.2.2 using the chosen diode of Part 1. Record the measured value of the resistance R. set the function generator to 1000 Hz, 8 V p-p sinusoidal voltage using the oscilloscope. + Vd - D1 1N4001 f = 1000 Hz R1 2.2k + Vo Figure 2.2 half wave rectifier b) The sinusoidal input of fig2.2 has been plotted on the screen of fig Figure 2.3 EEE 2116 Electronics I Lab. Page 2 of 8

3 c) Using the threshold voltage V T of Part 1, determine the theoretical output voltage v O for the circuit of fig 2.2 and sketch the waveform on fig 2.3 for one full cycle using the same sensitivities employed in Part 2(b). Indicate maximum and minimum values. d) Using the oscilloscope with the DC position, obtain the voltage v O and sketch the waveform on fig.2.4. Before viewing v O be sure to set the v O = 0 V line using the GND position of the coupling switch. Figure 2.4 e) Calculate the DC level of the half-wave rectifier signal of Part 2(d) using eq.2.1 f) Measure the DC level of v o using the DC scale of the DMM and find the percent difference between the measured value and the calculated value of part 2(e) using the following equation: VDC( calc) VDC( meas) %Difference X100% V DC( calc) (% Difference) = g) Reverse the diode of fig.2.2 and sketch the output waveform obtained using the oscilloscope on fig.4.5 Be sure the coupling is in the DC position. EEE 2116 Electronics I Lab. Page 3 of 8

4 figure 2.5 h) Calculate and measure the DC level of resulting waveform of fig.4.5. Insert the proper sign for the polarity of V DC as defined by fig.4.3 using eq.2.1 PART 3. Half-Wave Rectification (continued) a) Construct the network of fig.2.6. Record the measured value of resistor R. R1 2.2k + f = 1000 Hz D1 1N4001 Vo - figure 2.6 b) Using the threshold voltage of Part 1, determine the theoretical output voltage v o for fig.2.6 and sketch the waveform on fig.2.7 for one full cycle. Indicate the maximum and minimum values on the output waveform. EEE 2116 Electronics I Lab. Page 4 of 8

5 Figure 2.7 c) Using the oscilloscope with the coupling switch in the DC position, obtain the voltage v o and sketch the waveform on fig.2.8. figure 2.8 d) Calculate the DC level of the waveform of fig.2.8 using the following equation: TotalArea 2V m ( VT ) V DC 0.318V m VT / 2 volts 2 2 e) Measure the output DC voltage with the DC scale of the DMM and calculate the percent difference using the same equation appearing in Part 2(f). (% Difference) = EEE 2116 Electronics I Lab. Page 5 of 8

6 PART 5. Full-Wave Rectification a) Construct the full-wave bridge rectifier of fig Be sure that the diodes are inserted correctly and that the grounding is as shown. Figure 2.13 V rms (measured) = b) Using the V T of Part 1 for each diode, sketch the expected output waveform v o on fig Figure 2.14 c) Using the oscilloscope with coupling at DC position, obtain waveform v o and record it on fig.2.15 EEE 2116 Electronics I Lab. Page 6 of 8

7 Figure 2.15 d) determine DC level of the full-wave rectified waveform of fig e) Measure the output DC voltage with the DC scale of the DMM and calculate the percent difference using the same equation appearing in Part 2(f). (% Difference) = f) replace diodes D 3 and D 4 by 2.2 kohm resistors and forecast the appearance of the output voltage. Sketch the waveform on fig Figure 2.16 EEE 2116 Electronics I Lab. Page 7 of 8

8 g) using oscilloscope obtain waveform for output voltage and sketch it on fig.2.17 Figure 2.17 h) determine DC level of the full-wave rectified waveform of fig i) Measure the output DC voltage with the DC scale of the DMM and calculate the percent difference using the same equation appearing in Part 2(f). (% Difference) = Conclusion Write in 2-3 sentences at maximum. Why we obtain and measure the output voltage and DC coupling? Explain In full-wave rectification, what are the major differences between 4-diode bridge connection and replacing 2 of them with resistors? EEE 2116 Electronics I Lab. Page 8 of 8