BASIC ELECTRONICS - 18ELN14/24

MODULE1
SEMICONDUCTOR DIODES AND APPLICATIONS
1. Explain the operation of p-n junction diode under forward and reverse biased Condition
(dec/jan 2019----06M)
2.Explain how Zener diode can be used as a voltage regulator (dec/jan 2019----06M)
3.A diode circuit shown below has E=1.5V, R1=10 ohm. By assuming Vf=0.7V, calculate If
for
i) rd = 0
ii) rd = 0.25 ohm

4.With a neat circuit diagram and waveform, explain the working of half-wave rectifier and
derive the expression for average load current and ripple factor (dec/jan 2019----
06M)

5.Explain briefly the operation of a capacitor filter circuit.

6. Explain the operation of 7805 fixed IC voltage regulator
7.Explain the operation of PN junction diode under forward and reverse bias conditions
8.A full wave bridge rectifier with an input of 100V(rms) feeds a load of 1kΩ .VΩ .VT=0.7V
(i) If the diodes employed are of silicon, what is the dc voltage across the load?
(ii) Determine the PIV rating of each diode..
(iii) Determine the maximum current that each diode conducts and the diode power
rating.
9.Write a short note on
(i) Light emitting diode and (ii) Photo coupler
10.What is Zener diode? With neat circuit diagram, explain the operation of a voltage
regulator with and without load?
11.A silicon diode has IS=10nA operating at 25°C. Calculate In for a forward bias of 0.6V.

12.A half wave rectifier is fed from a supply of 230 V, 50 Hz with step down transformer of
ratio 3:1. Resistive load connected is 10 KΩ.orwadΩ. The diode forward resistance is 75Ω and
transformer secondary is 10 Ω. Calculate the DC load current, DC load voltage, efficiency
and ripple factor.

13.Write a short note on the following:

(i) Photo diode (ii) Light emitting diode (dec/jan 2019----04M)
(i)
14.With neat circuit diagram and wave forms explain the working of a centre tapped full
wave rectifier. (dec/jan 2019----
06M)

15.A Zener diode has a breakdown voltage of 10V. It is supplied from a voltage source
varying between 20-40V in series with a resistance of 820Ω. Using an ideal Zener model,
obtain the minimum and maximum Zener currents
16. Explain the working of half wave rectifier with capacitor filter with neat circuit diagram
and show the waveforms (dec/jan 2019----
06M)

Module-2
FET AND SCR
1. Explain the characteristics of N-channel JFET. (dec/jan 2019----
08M)

2. For E-MOSFET, determine value of ID, if ID (ON)= 4mA, Vgs(ON)=6V, VT=4V and
Vgs=8V.
3. Explain the construction and working of P-channel enhancement type MOSFET.
(dec/jan 2019----06M)
4. Explain phase-controlled application of SCR.
5. Explain the operation of a CMOS inverter. (dec/jan 2019----
08M)
6.Explain the construction and operation of JFET with necessary diagram
(dec/jan 2019----08M)

7.Draw and explain the V-I characteristics of SCR. (dec/jan 2019----08M)

8.With neat circuit diagram, explain the working of CMOS inverter.

9.What is MOSFET? Explain D- MOSFET and E- MOSFET transfer characteristics.
10.A certain JFET has an IGSS of -2nA for VGS= -20V Determine the input resistance.
11. Explain the construction and operation of a p-channel JFET
12. Explain the characteristics of an n-channel JEFT.
13. With neat diagram, explain the characteristics of a enhancement type MOSFET.
14. What is SCR? With neat diagram explain the two-transistor model of an SCR.
15. for a JFET Idss=9mA and Vgs=-8V determine the drain current for vgs=-4V(dec/jan
2019----04M)

MODULE-3
OPERATIONAL AMPLIFIER and APPLICATIONS
1.For an op-amp (i) List the characteristics of an ideal op-amp and Draw the three input
 inverting summer circuit and derive an expression for its output voltage.
2. Define the terms (dec/jan 2019----08M)
i) Slew rate
ii) CMRR
iii) Common mode gain AC of op-amp
3. Design an adder circuit using an op-amp to obtain an output voltage Vo=-
[2V1+3V2+5V3]
4. Find the output Vo of following op-amp circuit. (dec/jan 2019----06M)

5.Describe the characteristics of basic Op-Amp. List out its ideal characteristics.
6. A certain op-amp has an open loop voltage gain of 1,00,000 and a common
mode gain of 0.2. Determine the CMRR and express it in decibels.
7.Derive the output voltage for the following (i) Integrator and (ii) Voltage follower
8.Derive the output voltage of a non-inverting amplifier (dec/jan 2019----06M)
9.Explain the following with respect to op-amp (i) Input Impedance (ii) output impedance
(iii) Slew rate (iv) CMRR (v) virtual ground
10.Derive an expression for the output voltage of an inverting amplifier.
11.The input to the basic differentiator circuit is a sinusoidal voltage of peak value of 10mV
and frequency 1.5KΩ. TardHz. Find the output if, Rf=100KΩ.TardΩ and C1=1μF.F.
12.Derive an expression for the output voltage of an inverting summer.
13. A non-inverting amplifier circuit has an input resistance of 10KΩ. The diode forwardΩ and
feedback resistance 60KΩ.Thedio eforwadΩ with load resistance of 47KΩ.Thedio eforwadΩ. Draw the circuit. Calculate the
output voltage, voltage gain, load current when the input voltage is 1.5V.
14. Explin the block diagram of opamp (dec/jan 2019----06M)
15.Explain opamp as a substractor (dec/jan 2019----08M)
Module4
BJT AND ITS APPLICATIONS
1.Explain the operation of BJT as an amplifier and as a switch. (dec/jan 2019----
08M)
2.Draw and explain the operation of a voltage series feedback amplifier and derive an
expression for its voltage gain with feedback. (dec/jan
2019----04M)
3.Explain the Barkhausens’ criteria for oscillations.
4.Explain the working of an Astable oscillator constructed using IC- 555 timer.
5.What is an amplifier? Explain the operation of transistor amplifier circuit.
6.Define feedbackΩ .V amplifier? With necessary diagram and equation explain the different
types of feedbackΩ .V?
7.Explain how 555 timer can be used as an oscillator. (dec/jan 2019----08M)
8.Define an oscillator? Derive the equation for Wien bridge oscillator
9.Explain how the transistor can be used as a switch and as an amplifier.
A0
10.An amplifier has a high frequency response described by A= .
1+( jωω/ ω 2)
Where in A0=1000, ω2=104 rad/s. Find the feedback factor which will raise the upper
corner frequency ω2 to 105 Hz. What is the corresponding gain of the amplifier? Find also
the gain bandwidth product in this case.
11.With a neat circuit diagram, explain the working of RC phase shift oscillator
(dec/jan 2019----08M)
12.List the advantages of negative feedback in an amplifier. Explain the voltage series
feedback amplifier.
13.Show that the gain band width product for a feedback amplifier is constant.
14.The frequency sensitivity arms of the Wein bridge oscillator uses C1=C2=0.01μF.F and R1=10KΩ. The diode forwardΩ
while R2 is kept variable. The frequency is to be varied from 10KΩ. The diode forwardHz to 50 KΩ. The dio e forwadHz by
varying R2. Find the minimum and maximum values of R2.
Module-5
DIGITAL ELECTRONICS
1.Convert the following.
i) (725.25)10=( ? )2 = ( ? )16
ii) (111100111110001)2= ( ? )10 = ( ? )16
2.Simplify the following expressions and draw the logic circuits using basic gates.
i) AB+ A´C + A B´ C (AB+C)
ii) (A+ B´ )(CD+E)
3. Design full adder circuit using three variables and implement it using two half adders.
(dec/jan 2019----10M)
4.What is a multiplexer? Explain the working of 4:1 multiplexer.
5.With the help of a logic diagram and truth table, explain the working of a clocked SRflip-
flop(dec/jan 2019----06M).
6. What is a shift register? Explain the working of a 4-bit SISO shift register
7. Perform the following
(i) Convert (A B C D)16 =(?)2=(?)8=(?)10 (dec/jan 2019----04M)
(ii) Subtract (1010)2-(111)2 using 2’s compliment method. (dec/jan 2019----
02M)
8.Realize Y=AB+CD+E using NAND gates.
9.What is a flip flop? Explain the Master Slave JK flip flop operation.
10.With a neat blockΩ .V diagram explain GSM system.
11. Perform the following
(i) Convert (111110101101)2 to ( )8
(ii) Subtract (22)2-(17)2 using 1’s and 2’s compliment method.
12.What is a counter? With a neat timing and blockΩ .V diagram, explain three bit asynchronous
counter operation. (dec/jan 2019----08M)
13.Simplify the following Boolean expressions
(i) Y = A B´ + AB
(ii) Y = AB + AC + BD+ CD
(iii) Y =(B+CA )(C + A´ B)
(iv) Y = A´ B´ C´ D´ + A´ B´ C´ D+ A B´ C´ D´ + A B´ C´ D
14.With a neat circuit diagram and truth table, explain the working of a JKΩ.Thedio eforwad flip flop.
15. With a neat diagram, explain the working of a communication system.
(dec/jan 2019----08M)
16.Simplify and realize the following using NAND gates only
(i) Y = AC + ABC + A´ BC + AB+ D
(ii) Y = A B´ C´ + A´ B´ C´ + A´ B´ + A´ C´
17. state and prove de morgans theorem (dec/jan 2019----04M)