Explain properties of negative feedback. A power amplifier with a gain of 100 <0o has an output of 12V at 1.5 khz along with a second harmonic content of 25%. A negative feedback is to be provided to reduce the harmonic content of the output to 2.5%. What should be the gain of the feedback path and the level of signal input to the overall system? Attempt any two parts of the following: 5 x 2 = 10 (a) Explain the working of Hartley Oscillator with suitable diagrarn. Give its expression for frequency of oscillation. (b) For the block diagram given A = 60 < 90o, and B= 30 <90o at a certain frequency. Find the value of C for the system to be oscillatory. (b) 5. 6. (c) Explain phase shift oscillator and derive the relation for the frequency of oscillation. Attempt any two parts of the following: 5 x 2 = 10 (a) Realize a JK flip flop using AND and NOR gate only. (b) Design a mod- 9 counter by cascading two mod-3 counter of given figure. Give the table showing the sequence of state. (c) 7. Explain multiplexer and demultiplexer with their block diagram, logic diagram and truth table. Attempt any two parts of the following: 5 x 2 = 10 (a) Explain ROM with the help of block diagram. Also show the array of diodes. (b) Explain monostable multivibrator and derive the relation for pulse width and restoration time and output characteristic. (c) Write a short note on Switch Mode power Supply (SMPS).