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Code No: NR221003

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II B.Tech II Semester Supplimentary Examinations, Apr/May 2009 PULSE AND DIGITAL CIRCUITS ( Common to Electronics & Instrumentation Engineering and Electronics & Control Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ????? 1. Draw the output of the low pass RC circuit for different time constants to

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(a) square wave input, (b) pulse input and

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(c) step voltage input.

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Derive the necessary equations

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2. (a) In the circuit shown in figure 2a. Rf = 1K, Rr = 100K Vγ = 0. Sketch the output waveform V0 indicating all voltage levels and time constants for the given input waveform Vi . [10]

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Figure 2a (b) Draw the basic circuit diagram of positive peak clamper circuit and explain its operation. [6]

3. (a) Explain in detail the junction diode switching times. (b) Give a brief note on piece-wise linear diode characteristics.

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4. Explain how to draw the various waveforms and calculate their volatage levels in an emitter-coupled monostable multi. [16] 5. (a) Draw the circuit of a monostable bootstrap time-base generator and explain its working. [8] (b) What is the effect of Recovery interval on the sweep output? How do you get minimum recovery time in a bootstrap time base circuit? [8] 1 of 2

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Code No: NR221003

6. (a) Illustrate the terms ‘synchronization’ and ‘frequency division’ of a sweep generator. [8]

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(b) A free-running relaxation oscillator has sweep amplitude of 100 V and a period of 1 msec synchronizing pulses are applied to the device such that breakdown voltage is lowered by 50 V at each pulse. The synchronizing pulse frequency is 4 kHz. What is the amplitude and frequency of synchronized oscillator waveform? [8]

7. (a) Illustrate with neat circuit diagram, the operation of unidirectional sampling gate for multiple inputs. [8]

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(b) Explain with circuit diagram the operation of a two input sampling gate which does not have any loading effect on control signal. [8]

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8. What is meant by blocking oscillator? Explain the principle of operation of monostable blocking oscillator with base timing. Sketch the current waveforms and derive an expression for current pulse width. [16]

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