### GATE 2009 ECE Video Solutions on Analog Circuits (Analog Electronics)

1. In the following Astable Multivibrator circuit, which properties of Vo(t) depend on R2 ?

a. Only the frequency
b. Only the amplitude
c. Both the amplitude and the frequency
d. Neither the amplitude nor the frequency
Solution: https://www.youtube.com/watch?v=CNrhstw1lQI

2. In the circuit shown below, the OP-AMP is ideal, the transistor has VBE = 0.6 volts and β = 150. Decide whether the feedback in the circuit is positive or negative and determine the voltage V at the output of the OP-AMP.

a. Positive feedback, V = 10 Volts
b. Positive feedback, V = 0 Volts
c. Negative feedback, V = 5 Volts
d. Negative feedback, V = 2 Volts
Solution: https://www.youtube.com/watch?v=H6FpEgr7ZYI

3. A small signal source Vi(t) = Acos20t + Bsin106t is applied to a transistor amplifier as shown below. The transistor has β = 150 and hie = 3 KΩ. Which expression best approximate Vo(t).

a. Vo(t) = - 1500 (Acos20t + Bsin106t)
b. Vo(t) = - 150 (Acos20t + Bsin106t)
c. Vo(t) = - 1500 (Bsin106t)
d. Vo(t) = - 150 (Bsin106t)
Solution: https://www.youtube.com/watch?v=C-1mKYDJhY4

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