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TUTORIAL SHEET
ELECTRONICS ENGINEERING NEC101/201
UNIT-1
SEMICONDUCTOR DIODES AND ITS APPLICATIONS
1.
a.
b.
c.
Determine the dc resistance levels for the diode of Fig. at
ID =2 mA
ID =20 mA
VD=10 V
2. (a). Determine the diode current at 20°C for a silicon diode with Is = 50 nA and an applied forward bias
of 0.6 V.
(b).Determine the diode current at 20°C for a silicon diode with Is = 0.1 A at a reverse-bias potential of
-10 V.
3. In the reverse-bias region the saturation current of a silicon diode is about 0.1 A (T =20°C). Determine its
approximate value if the temperature is increased 40°C.
4.
5. Determine Vo and ID for the series circuit of Fig. also determine these values when P and N terminals of
diode are interchanged.
6. Determine the current I for the network of Fig.
7.
Determine the output waveform for the given clamper circuit.
8.
Determine the output waveform for the given clamper circuit.
9.
What is the magnitude of dynamic resistance “r”, for Silicon p-n junction diode at room temperature
and for forward current of 1mA?
10. Determine the output waveform for the given clamper circuit.
11.
Design a clamper circuit for input and output waveforms shown in figure below.
12.
Sketch vo for the network of Fig. and determine the dc voltage available.
13.
For the Zener diode network of fig, determine VL, VR, IZ, and PZ.
14. Determine the range of Vi that will maintain VL at 8 V and not exceed the maximum power rating of the
Zener diode.
15. Determine the range of RL and IL that will result in VRL being maintained at 10 V. Also determine the
maximum wattage rating of the diode.
16. Determine the output voltage waveform.
17. Determine the output voltage waveform.
18. A full wave rectifier with centre tapped transformer supplies a dc current of 100mA to a load resistance of
R=20Ω. The secondary resistance of transformer is 1. Each diode has a forward resistance of 0.5Ω. Determine
(a) rms voltage across each half of secondary (b) d.c power supplied the load (c) a.c power (d) PIV across
each diode and (e) conversion efficiency.
19. A 220V, 50Hz voltage is applied to the primary of 4:1 step down transformer, which is used in a bridge
rectifier, having a load resistance of 1k ohm. Assuming diodes to be an ideal, determine the following: (a) d.c.
output voltage (b) d.c. power delivered to the load (c) PIV of each diode (d) output frequency.
20. A sinusoidal voltage of 40V and frequency 50 Hz is applied to a half wave rectifier. RL=200 Ohm, RF=20
Ohm, Find VDC, IDC, IMAX, IRMS, PDC, Efficiency, ripple factor.
21. The forward resistance of diode is 20 ohm. This diode is used in a half wave rectifier circuit. The
applied input voltage is v=60 sin wt and load resistance is 800ohm.
UNIT-2
BIPOLAR TRANSISTOR AND FIELD EFFECT TRANSISTOR
1. In a transistor Ic=0.95 mA IE=1.05 mA. Determine β and α in C-E configuration.
2. Determine the following for the fixed-bias configuration of Figure. IBQ and ICQ, VCEQ, VB and
VC,VBC.
3. For the bias network of Figure below, determine: IB, IC, VCE, VC, VE, VB, VBC.
4. Determine the dc bias voltage VCE and the current IC for the voltage-divider configuration
of Figure shown below.
5. If the base current of transistor is 30  A , emitter current is 7.2 mA then what are the values of  and .
6. The alpha and beta of a transistor are 0.99 and 99 respectively. If its ICBO is 0.1  A then find ICEO?
7. In the voltage divider biasing circuit shown in figure-3, determine IC, VCC, VB, R1 and VB , if R1=62kΩ,
R2=9.1kΩ, RC=3.9kΩ, RE=0.68kΩ, Vcc=16 V and =20
8. Find the operating point of given circuit in figure. If +Vcc=10V, RC=10 kΩ, RB=180 kΩ and β=100.
9. Determine VCE and IC in voltage divider circuit if  DC=100.
10. If IDSS=9mA and VGS(off)= -8V(max.) then determine the drain current for VGS = 0 V, -1 V, and -4 V.
11. If IDSS=3.0 mA, VGS(off) = -6 V maximum, and using these values, determine the forward
transconductance for VGS = -4 V, and find ID at this point.
12. Sketch the transfer curve for a p-channel device with IDSS =4 mA and VP =3 V.
13. Determine the following for the network of Fig.(a) VGSQ (b) IDQ (c)VDS (d)VD. (e) VG. (f) VS.
14.
A transistor has current gain of 0.99 when used in common base (CB) configuration.
How much will be the current gain of this transistor in common emitter (CE)
configuration.
15. Given IE=2.5 mA, hfe=140, hoe=20 μS (μmho), and hob=0.5 μS, determine: The common-base re model.
16. Given β =120 and IE=3.2 mA for a common-emitter configuration with r0= ∞Ω,
determine:
(a) Zi.
(b) Av if a load of 2 kΩ is applied.
(c) Ai with the 2 kΩ load.
17. Given ID =4 mA at VGS=2 V, determine IDSS if VP=5 V.
18. Determine VC and VB for the network of Fig shown below-
19. Given IE=2.5 mA, hfe = 140, hoe= 20 S (mho), and hob= 0.5 S, determine:
(a) The common-emitter hybrid equivalent circuit.
20. Using the model of Fig., determine the following for a common-emitter amplifier if β=80, IE (dc)
=2 mA, and ro = 40 kΩ.
(a) Zi.
(b) Ib.
(c) Ai =Io/ Ii = IL /Ib if RL =1.2 kΩ.
(d) Av if RL = 1.2 kΩ.
Unit-3
Operational amplifier
1. A certain op-amp has an open-loop differential voltage gain of 100,000 and a common-mode
gain of 0.2, determine the CMRR and express it in decibels.
2. When a pulse is applied to an op-amp, the output voltage goes from -8 V to +7V in 0.75 ms.
What is the slew rate?
3. Discuss why negative feedback is used.
4. Determine the closed-loop voltage gain of the amplifier in Figure a.
a.
b.
5. Given the op-amp configuration in Figure, determine the value of Rf required to produce a
closed-loop voltage gain of -100.
6. Calculate the output voltage using the circuit of Figfor resistor components of value Rf =470 k
ohm, R1 =4.3 k, R2 =33 k, and R3 =33 k or an input of 80 microV.
7. Calculate the output voltage for the circuit of Fig below. The inputs are V1 =50 mV sin(1000t)
and V2 =10 mV sin(3000t).
8. Desing an amplifier with a gain of +9 and Rf=12 KΩ using an op-Amp.
9. In the figure shown if V1=+1V, V2=+3V and V3=+2V with R1=R2=R3=2KΩ. Determine the
output voltage.
10. A 5 mV peak voltage, 1 KHz signal is applied to the input of an Op-Amp integrator for which
R=100KΩ and C=1μF. Find the output voltage.
11. The input to a differentiator is a sindusoidal voltage of peak value 5mV and frequency 2KHz .
Find the output if R = 100KΩ and C=1μF.
12. The CMRR of a differential amplifier is 55 dB. If its gian in differential mode is 1200.then calculate its
gain in common mode.
13. Find the range of output voltage of the op-amp shown in figure.
14. Find the range of output voltage of the op-amp shown in figure.
15. Determine Vo for the summer of an opamp if V1=2V, V2= -1.5V ,V3=5V, R1=10K, R2=150K,
R3=50K and Rf =100K .
16. Calculate the output voltage of the circuit of Fig.
17. Calculate Vo for the circuit of Fig.
18. For an op-amp having a slew rate of SR = 2.4 V/μs, what is the maximum closed-loop voltage
gain that can be used when the input signal varies by 0.3 V in 10 s?
19. For an input of V1 = 50 mV in the circuit of Fig. , determine the maximum frequency that may
be used. The op-amp slew rate SR =0.4 V/s.
20. Calculate the input bias current at each input of an op-amp having specified values of IIO =
4 nA and IIB =20 nA.
Unit-4
Electronics instrumentation
1. What is the importance of Electron Gun Assembly, Vertical deflection plates, and Horizontal
deflection plates in CRO.
2. Explain : Intensity Control, Vertical position control, Focus Control.
3. For a Lissajous pattern find the frequencies of vertical to horizontal signals i.e find f V / f H.
a.
b.
c.
4. Difference between DSO and analog CRO.
5. Draw the diagram of lissajous pattern for fv /fh =3/1.
6. If fh= 3Khz then find the value of fv for given pattern.
a.
7.
8.
9.
10.
b.
c.
Write down the steps to measure the voltage of waveform shown on the screen of CRO.
Write down the steps to measure the time period of waveform shown on the screen of CRO.
Write down the steps to measure the frequency of waveform shown on the screen of CRO.
Calculate the phase difference of signal using lissajous pattern given below.
a.
b.
UNIT-5
BASICS OF COMMUNICATION
1. If Vmax = 10V, Vmin = 6V. Then calculate the depth of modulation.
2. If the amplitudes of the message signal and carrier signal are Am = 2V, Ac = 8V, then find the depth
of modulation.
3. A transmitter puts out a total power of 25 Watts of 30% AM signal. How much power is contained in
the carrier and each of the sidebands?
4. Calculate the total modulation index if the carrier wave is amplitude modulated by three modulating
signals with modulation indices 0.6, 0.3 and 0.4 respectively.
5. A carrier of 10 V peak and frequency 100 kHz is amplitude modulated by a sine wave of 4v peak and
frequency 1000Hz. Determine the modulation index for the modulated wave.
6. 400 watt carrier is modulated to a depth of 80%.calculate the total power in the modulated wave.
7. A broadcast transmitter radiates 20 kilowatts when the modulation percentage is 75. How much of
this is carrier power? Calculate power of each sideband.
8. A 100 kHz carrier is amplitude modulated by a 10 kHz sinusoidal wave. The carrier has amplitude of
20V and the square wave has amplitude of 5V. Sketch the frequency spectrum of the AM signal.
9. In an FM system, the frequency deviation is 5 kHz/V. If a sinusoidal modulating signal of 15V, 10
Khz is applied, calculate the bandwidth of the signal.
10. A multiple modulation signal m(t) consisting of two frequency components is given by
m(t)= cost+A2 cos t where 2 >1 and carrier signal is given by c(t)=AcCos c t.
Derive an expression for AM wave and plot frequency Vs amplitude spectrum.
11. Carrier wave of power 100W is subjected to a modulation index of 0.6 for amplitude modulation.
Determine the total power in sidebands and the power of modulated wave.
12. How many stations can be broadcast within a band of 12 Mhz bandwidth simultaneously without
interferring with each other? Take maximum audio signal frequency employed for modulated the
carrier not to exceed 15 Khz.
13. In an AM sysytem the modulating signal is sinosoidal wave frequency of fm Hz . If 80% modulation
is used, determine the ratio of side band power to total power in the modulated signal.
14. RMS value of RF voltage after amplitude modulation to a depth of 60% by a sinusoidal voltage is
60V. Calculate the RMS value of modulated voltage when modulted to a deptgh of 75%.
15. The current in the antenna of an AM transmitter is 8A when only the carrier is sent, but it increases to
9A when carrier is sinusoidally modulated, find the percentage modulation. Determmine the antenna
current when the depth of modulation is 0.77.
16. What should be the transmission bandwidth of FM signal with 75 KHz deviation and highest
frequency of modulation is 15KHz.
17. Determine the modulation index of an FM carrier having a frequency deviation of 25KHz and a
modulating signal of 5KHz. Also determine the carrier swing.
18. A carrier of 10cos8πx10^5t is amplitude modulated by a message signal of 6cosπx10^4t. Determine
modulation index, carrier power, total power, amplitude of each side band, bandwidth and efficiency
of AM. Also draw the spectrum of AM signal.
19. An AM signal is given by s(t)=4cos3200πt+10cos4000πt+4cos4800πt. Determine frequency of LSB
and USB, bandwidth, modulation index, amplitude of LSB and USB and efficiency.
20. For angle modulated signal m(t) = 10 cos[106 πt+5 sin (2π × 103)t]. Find maximum frequency
deviation and bandwidth.