questions on diode analysis: Assignment6
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This document contains the home assignment questions from an Introduction to Electronics course. It includes 9 questions related to analyzing circuits that contain diodes, rectifiers, and power supplies. The questions involve calculating voltage and current values, plotting waveforms, determining component ratings, and analyzing how circuits operate under different conditions.
questions on diode analysis: Assignment6
- 1. Department of Electrical Engineering, IIT Kanpur ESC 201A: Introduction to Electronics RL 11th Sept. 2014 Home Assignment-6 1. A single phase full wave rectifier is shown in the Figure 1. The transformer voltage is 35 V rms,50 Hz to center tap. A 160μF capacitor is connected in the output to filter out the load voltage ripple. A load of 250 Ω is connected in parallel with filter capacitor. The diode resistance and the transformer leakage reactance may be neglected. a) Calculate the cut out angle (the angle at which a diode stops conduction). b) Plot the output voltage V0 and diode current at steady state. c) Approximating the load voltage to be represented by the piece wise linear curve, draw a suitable Thevenin’s model for the rectifier circuit. d) Calculate average load current through 250Ω resistor and % regulation. C D1 35V 50Hz Vout + - Figure 1
- 2. Department of Electrical Engineering, IIT Kanpur ESC 201A: Introduction to Electronics -V0 + Vi 2. Determine the output waveform for the network of Figure 2. Assume the diodes are ideal. Calculate the output dc level and required PIV of each diode. 10 V ωt Figure 2(a) 2K 2K 2K Figure 2(b) 3. In the circuit shown in Figure 3, I is a dc current and Vi is a sinusoidal signal with small amplitude (less than 10 mV) and a frequency of 100 kHz. Representing the diode by its small - signal resistance rd, which is a function of I, (a) Sketch the circuit for determining the sinusoidal output voltage V0, and the thus find the phase shift between Vi and V0. (b) Find the value of I that will provide a phase shift of -450 and (c) Find the range of phase shift achieved as I is varies over the range of 0.1 to 10 times this value Assume n=1. Vi
- 3. Department of Electrical Engineering, IIT Kanpur ESC 201A: Introduction to Electronics DC C 10 nF I Figure 3 4. The circuit in Figure 4 implements a complementary output rectifier. Sketch and clearly label the waveforms of v0 + and v0 -. Assume a 0.7 V drop across each conducting diode. If the magnitude of the average of each output is to be 15V, find the required amplitude of the sine wave across the entire secondary winding. Figure 4 Vi V0 V0 + V0 -
- 4. Department of Electrical Engineering, IIT Kanpur ESC 201A: Introduction to Electronics V0 5. The Zener diode of Figure 5(a) is used in a certain application where the output voltage Vo is used to drive a load RL, connected parallel to the zener as shown in Figure 5(b). Calculate the following: a) Range over which Vo will vary when the input voltage is varied from 10 to 12 volts. b) Power rating required for the Zener diode. Assume no load conditions for (a) and (b). c) If Vi = 12 volts, find the range of load currents possible through RL for Vo > 6.2 volts. I (mA) 10 -6.5 -6.2 -6 5 0.9 -5 0.7 0.8 V (Volts) -10 Figure 5(a) 1K 10-12V Figure 5(b) Vi RL
- 5. Department of Electrical Engineering, IIT Kanpur ESC 201A: Introduction to Electronics 6. Determine the output voltage with reference to ground for the circuit shown in Figure 6(a) and Figure 6(b), assuming that cut-in voltage of both diode and Zener diode is 0.7V and that Zener voltage is 3V. 2V 1K D1 D2 6V 4.7V 1K D1 D2 1K Figure 6(a) Figure 6(b) 7. Design the power supply circuit shown in Figure 7 that will supply 10V to a load of 1000Ω with ripple voltage less than 0.2V. As part of the design, determine transformer turns ratio, value of capacitance, diode peak current and peak inverse voltage. Assume that input is 220V rms with a frequency of 50Hz. D1 C D2 Vs N1 N2 0 50 J… F o o… Figure 7 V0 V0 V0 RL
- 6. Department of Electrical Engineering, IIT Kanpur ESC 201A: Introduction to Electronics 8. In an unregulated DC power supply using center-tapped transformer, as shown in Figure 8 , we need to develop Vo = 8V across a 10Ω load (RL), with no more than 2% ripple present in Vo. Determine: a) The transformer turns ratio N, b) The value of the filter capacitor C, and c) The minimum breakdown voltage and the minimum peak current ratings of the diodes D1 and D2 (both using a safety factor of 2). Use first- order diode model with Vϒ = 0.6 V. C D1 D2 - + + - - + 230 V 50Hz Center-tapped transformer N:1 Figure 8 V0 RL
- 7. Department of Electrical Engineering, IIT Kanpur ESC 201A: Introduction to Electronics 9. A simple diode clamping circuit is shown in Figure 9. Draw the input and output waveforms for a sinusoidal input Vi, varying from -15V to +15V. Use second- order model for diodes D1 and D2 with V(gamma1) = V(gamma2) = 0.6 V, rF1 = 30 ohm and rF2 = 20 ohm. Here V (gamma) denotes the cut in voltage. - + + - + + - - Vi Vo Figure 9