JNTU
JNTU B.Tech III BASIC ELECTRONICS Previous Question Paper (November/December - 2018 - R13)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks and may have a, b, c as sub questions.
Part A
What is meant by cut-in voltage of a semiconductor diode? What is its value for germanium and silicon diode?
Answer
The cut-in voltage (or knee voltage) is the minimum forward bias voltage required across a diode to initiate significant current flow. For a germanium diode, it is approximately 0.3 V, and for a silicon diode, it is approximately 0.7 V.
Explain the working of a pn-junction as half wave rectifier.
Answer
A half-wave rectifier uses a single pn-junction diode in series with the load. During the positive half-cycle of the AC input, the diode is forward-biased and conducts current to the load. During the negative half-cycle, the diode is reverse-biased, acts as an open circuit, and blocks current, resulting in a pulsating DC output only during the positive half-cycles.
Describe the constructional features of a BJT.
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What are the three possible configurations of a transistor? Explain briefly.
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Name any three thyristor devices.
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Give the applications of triac.
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Define negative and positive feedback.
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State Barkhausen’s criterion.
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Give the classification of timer circuits.
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Give the principle of induction heating.
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Part B
Explain the operation of PN junction diode under forward and reverse bias. Draw the Volt-ampere characteristics.
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What is a filter circuit? Explain the operation of Full-wave rectifier with capacitor filter using relevant waveforms.
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Explain the input and output characteristics of a transistor in CB configuration.
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Draw the circuit diagram of a single stage common emitter amplifier. Explain its operation giving the function of each component. Draw its frequency response and explain.
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Draw the symbol, structure and VI characteristics of a Diac. Explain its working.
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Draw the symbol and structure of SCR. Draw the VI characteristics of SCR and explain.
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Draw the block diagram of a negative feedback amplifier and explain the function of each block. Give the relation between Af, A and β.
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Draw the circuit diagram of a RC Phase shift oscillator and explain its operation. What is its frequency of operation.
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What are the types of resistance welding and explain each of them?
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Draw the circuit and explain the operation of sequence timer.
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Draw the circuit and explain the operation of capacitor energy storage welder.
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