Basic Electronics Jntu Btech 2008

Basic Electronics Jntu Btech 2008

• 1.
  www.studentyogi.com www.studentyogi.com Code No: R05220301 Set No. 1 II B.Tech II Semester Regular Examinations, Apr/May 2008 BASIC ELECTRONICS ( Common to Mechanical Engineering and Production Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks 1. (a) Explain why a semi conductor acts as an insulator at 0o k and why its con- ductivity increases with increase of temperature. (b) Draw the circuit of Bridge recti er and explain the working of it. Give its merits and de-merits. [4+12] 2. (a) Explain why CE con guration is commonly used in ampli er circuits. (b) Draw the structure of J F E T and explain in detail the e ect of gate-source voltage on the channel when [4+12] i. No bias ii. small reverse bias and iii. large reverse bias such that pinch-o occurs. 3. (a) Draw the basic circuit for obtaining the static V-I characteristics of thyristor. (b) Draw the V-I characteristics of SCR and account for the shape of the charac- teristics [6+10] 4. (a) Explain how negative feedback improves the stability of gain of the ampli er for changes in power supply voltage or change in the parameters of the active device. What is the condition to achieve the stability of the gain. (b) Calculate the gain of a negative feedback ampli er with internal gain A = 500 and feed- back factor = 0.01. If the output impedance of the internal ampli er is 80 k , determine the output impedance of the feedback ampli er. [8+8] 5. (a) Classify oscillators based on i. output waveform ii. operating frequencies. (b) Draw the circuit of Colpitts Oscillator using transistor and explain the working of it. [6+10] 6. (a) Explain the following type of Timers i. Electro-mechanical Timers. ii. Electronic Timers. (b) List di erent welding circuits
• 2.
  www.studentyogi.com www.studentyogi.com Code No: R05220301 Set No. 1 7. (a) List di erent applications of Ultrasonic Waves and explain the principle and working of Pulsed-echo Ultrasonic Flow Detector. (b) Explain the principle of Dielectric heating. [10+6] 8. (a) List various characteristics of A-to-D converter. (b) Compare three A-to-D conversion techniques. [8+8]
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  www.studentyogi.com www.studentyogi.com Code No: R05220301 Set No. 2 II B.Tech II Semester Regular Examinations, Apr/May 2008 BASIC ELECTRONICS ( Common to Mechanical Engineering and Production Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks 1. (a) Explain the concept of “ hole” in a semi conductor. (b) Explain the di erence between Ideal Diode and commercial diode with the help of V-I Characteristics . (c) Draw the circuit of Half wave recti er with L- section lter and explain the working of it. [4+4+8] 2. (a) Explain why CE con guration is commonly used in ampli er circuits. (b) Draw the structure of J F E T and explain in detail the e ect of gate-source voltage on the channel when [4+12] i. No bias ii. small reverse bias and iii. large reverse bias such that pinch-o occurs. 3. (a) Name di erent methods of turning-on of SCR. (b) What are the important points to be noted while designing the gate-control circuit of SCR. (c) Draw and explain the V-I characteristics of SCR. [2+6+8] 4. (a) Explain how the negative feedback increases the input impedance and reduces the output impedance and derive the expressions for input and output im- pedance of the feedback ampli er. (b) An ampli er without feedback has a gain of 1200, input impedance of 1.5 k . and output impedance of 50 k . Determine the values of input and output impedances of feedback ampli er with a feedback factor of 0.01. [10+6] 5. (a) Why phase shift through the R-C feed back network of R-C phase shift oscil- lator is to be 1800? Explain. (b) What are the limitations of R C-Phase shift oscillators? (c) Draw the circuit of Colpitts Oscillator and explain the working of it. [5+3+8] 6. (a) Name principal types of resistance welding processes and brie y explain them. (b) Brie y explain the principle of working of any one type of Thermal Timers. [12+4] 7. (a) Giving basic set up, explain the principle of Induction heating.
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  www.studentyogi.com www.studentyogi.com Code No: R05220301 Set No. 2 (b) Draw and explain piezo electric generator circuit using Hartley oscillator for generation of Ultrasonic waves. [8+8] 8. (a) Explain the operation of counter type A-to-D converter using D-to-A con- verter. (b) Explain various status ags provided in 8085. [10+6]
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  www.studentyogi.com www.studentyogi.com Code No: R05220301 Set No. 3 II B.Tech II Semester Regular Examinations, Apr/May 2008 BASIC ELECTRONICS ( Common to Mechanical Engineering and Production Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks 1. (a) Explain why a semi conductor acts as an insulator at 0o k and why its con- ductivity increases with increase of temperature. (b) Draw the circuit of Bridge recti er and explain the working of it. Give its merits and de-merits. [4+12] 2. (a) Explain why CE con guration is commonly used in ampli er circuits. (b) Draw the structure of J F E T and explain in detail the e ect of gate-source voltage on the channel when [4+12] i. No bias ii. small reverse bias and iii. large reverse bias such that pinch-o occurs. 3. (a) Name di erent methods of turning-on of SCR. (b) What are the important points to be noted while designing the gate-control circuit of SCR. (c) Draw and explain the V-I characteristics of SCR. [2+6+8] 4. (a) Draw block diagrams and brie y explain the four types of feedbacks in ampli- ers. (b) An ampli er without feedback has A = 5000, lower cut-o frequency L = 2.5 Hz, upper cut-o frequency H = 100 kHz, output resistance 0=2000 . If negative feed- back in applied to make the output resistance 0f = 600 , calculate the value of , voltage gain and half power frequencies of the feedback ampli er. [8+8] 5. (a) Classify oscillators based on i. output waveform ii. operating frequencies. (b) Draw the circuit of Colpitts Oscillator using transistor and explain the working of it. [6+10] 6. (a) Draw and explain the heat control circuit for resistance welding. (b) Compare and contrast the following timers: [8+8] i. Thermal Timers
• 6.
  www.studentyogi.com www.studentyogi.com Code No: R05220301 Set No. 3 iii. Electronic Timers. 7. (a) Explain the application of Induction Heating for i. Brazing and ii. Annealing of Brass and Bronze items . (b) Explain the construction and working of a C R tube with neat diagram [8+8] 8. (a) Explain the operation of counter type A-to-D converter using D-to-A con- verter. (b) Explain various status ags provided in 8085. [10+6]
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  www.studentyogi.com www.studentyogi.com Code No: R05220301 Set No. 4 II B.Tech II Semester Regular Examinations, Apr/May 2008 BASIC ELECTRONICS ( Common to Mechanical Engineering and Production Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks 1. (a) Explain what is meant by mobility of a charge carrier in a solid. Derive an expression for the conductivity of a semiconductor, containing both free electrons and holes, in terms of the concentrations n and p and the mobilities. (b) Draw the circuit of Bridge recti er and explain the working of it. [8+8] 2. (a) Explain why CE con guration is commonly used in ampli er circuits. (b) Draw the structure of J F E T and explain in detail the e ect of gate-source voltage on the channel when [4+12] i. No bias ii. small reverse bias and iii. large reverse bias such that pinch-o occurs. 3. (a) Name di erent methods of turning-on of SCR. (b) What are the important points to be noted while designing the gate-control circuit of SCR. (c) Draw and explain the V-I characteristics of SCR. [2+6+8] 4. (a) Explain the e ect of negative feedback on distortion, gain, band-width and input and output impedances of the ampli er. (b) In an ampli er an output of 60 V, is obtained for an input signal of 0.6V. This circuit is now connected to a negative feedback networks such that 20% of the output voltage goes back to the input side. Calculate the increased value of input, if we want the same output from the circuit (i.e. 60 V). [8+8] 5. (a) Draw the circuit of transistor Colpitts Oscillator and brie y explain the work- ing of it. Derive the expression for frequency of oscillation o. (b) Calculate the frequency of oscillation of a transistor Colpitts Oscillator having 1 = 0.02 F, 2 = 0.2 F and L = 10 H. [10+6] 6. (a) Brie y explain “Thermal Expansion timers”. (b) Draw sequence Timer Welding Circuit and explain its operation. [6+10] 7. (a) Explain the principle of Dielectric heating and List the applications of Dielec- tric heating. (b) Explain the use of Ultrasonic waves in Degassing of liquids.
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  www.studentyogi.com www.studentyogi.com Code No: R05220301 Set No. 4 8. (a) What are the functional units of central processing unit in 8085. Brie y ex- plain each of them. (b) What is stack in 8085? What are its functions? [8+8]