Electric Circuits Answers

Design and draw the circuit of a three channel op-amp adder with channel gains of
−5, −10 and −15 respectively.

Draw a circuit of a non-inverting amplifier with gain 1 using op-amp. Draw the
output voltage curve of this circuit for a step input of 5V amplitude and 50 kHz
frequency, if the slew rate of the op-amp is 0.5 V/μs. (Use proper scale on the time
axis to illustrate the effect of slew rate).

In a voltage regulator circuit, the output voltage under no load condition is 12V
while under full load it is 11.8V. Over the full range of input voltage variation the
nominal voltage output of 12V varies by 50 mV. Calculate percentage line and load
regulation.

State the Barkhausen criterion for sustained oscillation. Explain the operation of
Colpitt Oscillator. For a Colpitt oscillator with 10 MHz frequency determine the
equivalent capacitance, C forming tank circuit with 0.1 mH inductor.

h-parameters of a single stage CE amplifier are given as hie = 1 kW , hre = 3 × 10−4,
hfe = 60 and hoe = 25 μA/V. Calculate Ai, Av and Zout with rs =100W and rL =10kW.

Refer to the universal bias shown in Fig. 4.11 of your study material. If Vcc = 10V,
R1 = R2 = RC = RE = 10kW, VBE = 0.7V and b = 100, calculate VB, VE, IE, IB, VC and
VCE.

Which processes are responsible for the charge carrier transport in a semiconductor?
Which of these govern in the case of a bulk semiconductor when no potential is
applied?

A series LCR circuit with L = 400 mH, C = 20 nF and R = 250
is connected to an
AC source of 65 V. Calculate the resonance frequency and Q of the circuit. What is
the current flowing through the circuit and voltage across the capacitor at resonance
frequency?

Explain with a neat diagram application of p-n junction diode as a peak voltage
detector.

State, with reasons, whether the following statements are True or False.
i) Ideal voltage source has infinite internal resistance.
ii) Transformer is a passive device hence it cannot increase the voltage.
iii) Field effect transistor (FET) is a current controlled device.
iv) Forward biasing of a semiconductor junction diode reduces its energy band gap.
v) Amplifier with common collector mode offers maximum voltage gain.
vi) Ripple factor of a center tapped full wave rectifier is greater than that of a bridge
rectifier, which uses four diodes.
vii) Operational amplifier in non-inverting mode cannot amplify negative signals.
viii) IC LM380 is a small signal amplifier used to amplify the voltage.
ix) Largest decimal number represented by a 2-digit hex number is 99.
x) In a CRO sweep generator output is given to the vertical deflection plates.