Analog Circuits Practice Test 10

1. The following is a shunt regulator. Find maximum power dissipation of the Zener diode and transistor, given that the source voltage varies from 20-40V, the Zener breakdown voltage is 5V, the output voltage is 10V, the resistance R1=50Ω, R2=20kΩ, β=99, V_BE=0.5V.

P_Transistor = 5.12 W, P_Zener = 0.051 W

P_Transistor = 0.41 W, P_Zener = 0.57 W

P_Transistor = 5.94 W, P_Zener = 0.057 W

P_Transistor = 6.22 W, P_Zener = 5.66 W

2. Which of the following correctly determines the relation between α and β?

β=α/(1-β)

α=β/(1-α)

β=α/(1-α)

β=α*(1-β)

3. Which is not a difference between active and passive filter?

A passive filter is used at audio frequency and an active at radio frequency

A passive filter can’t use an inductor while an active filter can

A passive filter performs only filtering while an active filter amplifies too

A passive filter does not use op-amp while an active filter uses an op-amp

4. From the given circuit, using a silicon BJT, what is the value of V_BC?

6.13 V

7 V

-7 V

-6.13 V

5. Given that the collector power dissipation is 300 mW, what is the value of collector to emitter voltage for collector current = 50 mA?

3 V

6 V

0 V

2 v

6. A filter is provided of order 3, find the roll-off rate.

60 dB/octave

3 dB/decade

60 dB/decade

6 dB/decade

7. Given that for an op-amp the gain is 10³, the slew rate is 1.5V/μsec. Input is 5x10^-3sinωt, calculate maximum frequency to prevent distortion.

477 Hz

47.7 kHz

3 kHz

0.3 MHz

8. Which of these is a not drawback of Zener diode shunt regulator?

It is difficult to design

The output voltage is fixed

The output voltage can vary with temperature

Variation in load current needs to be minimal

9. If the positive lead of a DMM, with the mode set to ohmmeter is connected to the base and the negative lead to the emitter and a low resistance reading is obtained, then what is the type of transistor that is being tested?

PNP

NPN

Not a transistor, it is a FET

Faulty transistor

10. In the figure below, the voltage V1 ranges from 15 to 35V. The load current is 20mA. The diode knee current is 2 mA, the breakdown voltage is 5V and power rating is 200 mW.

Calculate the range of R2 for the circuit to behave properly as a regulator.

450Ω =< R2 =< 500Ω

454Ω =< R2 =< 500Ω

400Ω =< R2 =< 500Ω

454Ω =< R2 =< 600Ω