Channabasaveshwara Institute of Technology (An ISO 9001:2008 Certified Institution)
NH 206 (B.H. Road), Gubbi, Tumkur – 572 216. Karnataka.
DEPARTMENT OF ELECTRICAL & ELECTRONICS ENGG.
CONTENTS
Exp.
No Title of the Experiment
Page
No
1 Full wave Rectifiers and Filters 2
2 Simplification, realization of Boolean expressions using logic
gates/Universal gates 8
3
Frequency response of single stage BJT and FET RC
coupled amplifier and determination of half power points, bandwidth, input and output impedances
12
4 Realization of half/Full adder and Half/Full Subtractors using logic gates
20
5 Design and testing of BJT - RC phase shift oscillator
26
6 a) Realization of parallel adder/Subtractors using 7483 30
b) Realization of BCD to Excess-3 and vice versa 32
7 Determination of gain, input and output impedance of BJT
Darlington emitter follower with and without bootstrapping. 36
8 Design and testing Ring counter/Johnson counter 42
9 Design and testing of Sequence generator 46
10
Realization of Binary to Gray code conversion and vice
versa. 48
11 Realization of 3 bit counters as a sequential circuit and MOD – N counter design using 7476, 7490, 74192, 74193.
56
12 Static Transistor characteristics for CE, CB and CC modes and determination of h parameters.
68
Additional Experiments 80
References 97
Annexure
Viva Questions 98
Question Bank 99
Components Data Sheets 101
[Electronics Lab : 17 EEL 38]
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 1
VDC
Circuit Diagram:
Full wave rectifier
a) Center tap FWR without filter b) Center tap FWR with ‘C’ filter
a) Bridge Rectifier without filter b) Bridge Rectifier with ‘C’ filter
Vi
Vm
2 t
Vo without filter
Vm
2 t
Vo with ‘C’ filter
Vrpp
VDC
2 t
D2
Vm
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Experiment No. : 1 Date: ___/____/_______
Rectifiers and Filters
Aim : To design and testing of Full wave – centre tapped transformer type and Bridge type
rectifier circuits with and without Capacitor filter. Determination of ripple factor, regulation and
efficiency
Apparatus Required :
Sl.
No. Particulars Range Quantity
1. Transformer As per design 01
2. Diode (BY 127) - 04
3. Resistors & Capacitors As per design -
4. Multimeter - 01
5. CRO Probes - 2 Set
6. Spring board and connecting wires - -
Theory:
Rectifier is a circuit which converts AC to pulsating DC. Rectifiers are used in
construction of DC power supplies. There are three types of rectifiers namely Half wave
rectifier, Center tap full wave rectifier and bridge rectifier.
In half wave rectification, either the positive or negative half of the AC wave is
passed, while the other half is blocked. Because only one half of the input waveform reaches
the output, it is very inefficient if used for power transfer.
A full-wave rectifier converts the whole of the input waveform to one of constant
polarity (positive or negative) at its output. Full-wave rectification converts both polarities of
the input waveform to DC (direct current), and is more efficient. Fullwave rectification can
be obtained either by using center tap transformer or by using bridge rectifier.
The output of a rectifier is not a smooth DC it consists of ac ripples therefore to
convert this pulsating DC in to smooth DC we use a circuit called filter. There are many types
of filters like C filter, L filter, LC filter, multiple LC filter, filter etc.. of all these C filter is
the most fundamental filter.
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Design :
a) Center Tap Full Wave Rectifier / Bridge Rectifier Without filter
VDC = 2Vm / for FWR ( both center tap and bridge rectifier )
For the given VDC calculate Vm and Vrms = Vm / 2
Procedure :
1. Components / Equipment are tested for their good working condition
2. Connections are made as shown in the circuit diagram
3. Observe different waveforms on CRO
4. Measure VDC using multimeter in dc mode and Vm on CRO
5. Calculate Vrms from Vm using formula Vrms = Vm / 2 for Half wave rectifier
Vrms = Vm / 2 for full wave rectifier
6. Calculate the efficiency, ripple factor and regulation. Compare the results with the
theoretic values.
Result :
Without filter :
Type of rectifier
- theoretical - practical - theoretical - practical
Center tap full
wave rectifier 0.48
81.2 %
Bridge
Rectifier 0.48
81.2 %
With filter :
Type of rectifier
theoretical
practical % Regulation
Center tap full
wave rectifier 0.006
Bridge
Rectifier 0.006
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Choose the transformer of rating Vrms – 0 – Vrms / ≥ IDC for Center tap full wave rectifier
and 0 – Vrms / ≥ IDC for Bridge rectifier
The value of load resistance, RL = VDC / IDC, PRL = VDC2 / RL
b) Full Wave Rectifier with ‘C’ filter
VDC = Vm – ( IDC / 4fC )
= 1 / ( 4 3 fCRL ) ( f = 50 Hz )
For the given value of VDC and IDC Calculate RL = VDC / IDC, PRL = VDC2 / RL
For the given Calculate the value of capacitor ‘C’
For the given value of VDC and IDC Calculate Vm and Vrms = Vm / 2
Choose the transformer of rating,
Vrms – 0 – Vrms / ≥ IDC for Center tap full wave rectifier and 0 – Vrms / ≥ IDC for Bridge
rectifier
Choose the capacitor of value C / ≥ Vm
Example - 1: Design an FWR for an output DC voltage of 10 V and load current of
10 mA. (Bridge and Center tap rectifier)
VDC = 10 V
Vm = (VDC X ) / 2 = 15.7 V
Vrms = Vm / 2 = 11.1 V 12 V
Choose a transformer of rating 12V – 0 – 12V / ≥ 10 mA for Center tap full wave rectifier
Choose a transformer of rating 0 – 12V / ≥ 10 mA for Bridge rectifier
RL = VDC / IDC = 1 K
PRL = VDC2 / RL = 0.1 W
Choose RL = 1 K / 0.1 W
Example – 2 : Design a full wave rectifier for VDC = 16 V, IDC = 16mA, = 0.006 (Bridge
and center tap rectifier)
RL = VDC / IDC = 1 K, PRL = VDC2 / RL = 0256 W
From = 1 / ( 4 3 fCRL ), C = 481 f, ( 470f ) ( f = 50 Hz )
From VDC = Vm – ( IDC / 4fC ), Vm = 16.17 V, Vrms = 11.43 V, ( 12 V )
Choose transformer of rating 12V - 0 – 12V / ≥ 16mA for center tap full wave rectifier
and 0 – 12V / ≥ 16mA for bridge rectifier
Choose RL = 1 K / 0.256 W, C = 470 f / ≥ 16.17V
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Tabular Column :
Without filter
Circuit VDC Vm Vrms =VDC2 / Vrms2
= (Vrms2 / VDC2)-1
Center tap full
wave rectifier
Bridge
Rectifier
Note : Vrms = Vm / 2 for Half wave rectifier Vrms = Vm / 2 for full wave rectifier
With filter :
Circuit VDC
full load Vrpp Vrrms
VDC
no load
%
Regulation = Vrrms / VDC
Center tap full
wave rectifier
Bridge
rectifier
Note : Vrrms = Vrpp / 23
% Regulation = ( VDC no load – VDC full load ) / VDC full load
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1) Y1=(A+BC)(B+A C ) using Basic Gates
Simplification:
Y1=(A+BC)(B+A C ) ( Given Expression)
= AB+ A C +BC (Using basic gates)
= BC+ CA +AB
=
Y1= ( A+BC)(B+ A C )
= (A+B)(A+C)(B+A)(B+C )
= ))()(( CBBACA
=
A B C
Y1
AB . BC . CA (Using NAND Gates)
)( CA + )( BA + ( )CB (Using only NOR gates)
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Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 8
Experiment No. : 2 Date: ___/____/_______
Simplification and Realization of Boolean Expression using logic
gates/Universal gates
Aim: Simplify and realize the given Boolean expressions using Logic Gates/Universal Gates
Apparatus:
Sl No Particulars Quantity
1 IC 7408,IC 7432 2 each
2 IC 7400,IC 7402 2 each
3 IC 7410 1
Theory:
Canonical Forms (Normal Forms): Any Boolean function can be written in
disjunctive normal form (sum of min-terms) or conjunctive normal form (product of max-
terms).A Boolean function can be represented by a Karnaugh map in which each cell
corresponds two minterm. Sum of minterms : Sum Of Product (SOP) Product of maxterms : Product Of Sum (POS)
Procedure: 1. Verify that the gates are working.
2. Construct a truth table for the given problem.
3. Draw a Karnaugh Map corresponding to the given truth table.
4. Simplify the given Boolean expression manually using the Karnaugh Map.
A. Implementation Using Logic Gates 1. Realize the simplified expression using logic gates.
2. Make connections as per the logic gate diagram.
3. Apply the different combinations of input according to the truth tables.
4. Verify that the results are correct.
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B. Implementation Using Universal Gates
1. Convert the AND-OR logic into NAND-NAND and NOR-NOR logic. 2. Implement the simplified Boolean expressions using only NAND gates, and then using
only NOR gates. 3. Connect the circuits according to the circuit diagrams, apply inputs according
to the truth table and verify the results.
Using Only NAND gates
Using only NOR gates Truth Table
A B C Y1
0 0 0 0
0 0 1 0
0 1 0 0
0 1 1 1
1 0 0 1
1 0 1 0
1 1 0 1
1 1 1 1
A B C
Y
1
1
A B C
Y1
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2) Z= A B C +ABC + A B C+ABC
= A B (C+C )+AB(C+ C )
= A B +AB (using Basic Gates)
Z=
Z=
Using NAND Gates Only
Using NOR Gates only
Exercise : (i) ((A+B) C)'D (ii) A + (BC)' + (CD)'
A B + AB ( Using only NAND Gates)
(A+ B )+( A +B) ( Using only NOR Gates)
A
B
Z
Z
A B
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Circuit Diagram:
RC coupled Single stage BJT amplifier:
Design :
Given, VCE = 5 V and IC = 2 mA Assume = 100
VCC = 2VCE = 2 X 5 = 10 V
Let VRE = 10% VCC = 1 V
RE = VRE / ( IC + IB )
IB = IC / = 2mA / 100 = 20 A
RE = 1 / ( 2m + 20 ) = 495
Choose RE = 470
Apply KVL to collector loop
VCC – IC RC – VCE – VE = 0
RC = (VCC – VCE – VE) / IC = (10 – 5 – 1) / 2 m
RC = 2 K Choose RC = 1.8 K
Let IR1 = 10 IB = 10 X 20 A = 200 A
VR2 = VBE + VE = 0.6 + 1 = 1.6 V ( Since transistor is silicon make VBE = 0.6 V )
R2 = VR2 / ( IR1 – IB ) = 1.6 / ( 200 A - 20 A )
R2 = 8.8 K Choose R2 = 8.2 K
R1 = ( VCC – VR2 ) / IR1 = ( 10 – 1.6 ) / 200 A
R1 = 42 K Choose R1 = 47 K
XCE < < RE
XCE = RE / 10
_
IR1
VR2
C
B
E
SL100
or
CL100 0.1F
0.1F
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Experiment No. : 3 Date: ___/____/_______
3a. RC Coupled Single Stage BJT Amplifier
Aim: To conduct an experiment to plot the frequency response of an RC coupled amplifier
and to find the half power points, bandwidth, input impedance, output impedance.
Apparatus Required:
Sl.
No. Particulars Range Quantity
1. Transistor SL 100 - 01
2. Resistors & Capacitors As per design -
3. CRO Probes - 3 Set
4. Multi meter - 01
5. DRB - 01
6. Spring board and connecting wires - -
Theory :
An amplifier is a circuit which increases the voltage, current or power level of i/p
signal where the frequency is maintained constant from o/p to i/p signal. The common emitter
amplifier is basically a current amplifier ( IC = Ib ) where IB is input current and IC is output
current and is a non unity value, in turn it provides voltage amplification. The ratio of
collector current to base current is noted as the current amplification factor and is denoted as
‘’i.e.[ = IC/Ib], is very large.
In RC coupled CE amplifier R1, R2 and RC are selected in such a way that transistor
operates in active region and the operating point will be in the middle of active region. RE is
used for stabilization of operating point. Coupling capacitors CC1 and CC2 are used to block
dc current flow through load and the source. The emitter by-pass capacitor CE is connected to
avoid negative feedback. Input signal increases base current and the collector current
increases by a factor . [i.e. Ic = Ib]. Hence output voltage is large compared to input
voltage which is known as amplification
An amplifier in which resistance-capacitance coupling is employed between stages
and at the input and an output point of the circuit is known as RC coupled amplifier. A
capacitor provides a path for signal currents between stages, with resistors connected from
each side of the capacitor to the power supply or to ground.
1 / ( 2 f CE ) = 470 / 10 Let f = 100 Hz
CE = 33 F Choose CE = 47 F
Choose CC1 = CC2 = 0.1 F
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Tabular Column : Vi = ___________ V
F in Hz Vo in Volt AV = Vo / Vi Gain in dB = 20*log
AV
Procedure :
1. Components / Equipment are tested for their good working condition.
2. Connections are made as shown in the circuit diagram.
3. By keeping the voltage knobs in minimum position and current knob in maximum
position switch on the power supply.
4. By disconnecting the AC source measure the quiescent point (VCE and IC = VRC / RC)
To find frequency response :
1. Connect the AC source. Keeping the frequency of the AC source in mid band region
(say 10 kHz) adjust the amplitude to get the distortion less output. Note down the
amplitude of the input signal.
2. Keeping the input amplitude constant, Vary the frequency in suitable steps and note
down the corresponding output amplitude.
3. Calculate AV and gain in decibels. Plot a graph of frequency Vs gain in dB. From the
graph calculate f L, f H and band width.
4. Calculate figure of merit.
To find the input impedance ( Zi ) :
1. Connections are made as shown in the diagram.
2. Keeping the DRB in its minimum position, apply input signal at mid band frequency
(say 10kHz) and adjust the amplitude of the input signal to get distortion less output.
Note down the output amplitude.
3. Vary the DRB until the output amplitude becomes half of its previous value. The
corresponding DRB value gives the input impedance.
To find the output impedance ( Zo ) :
1. Connections are made as shown in the diagram.
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2. Keeping the DRB in its maximum position, apply input signal at mid band frequency
(say 10kHz) and adjust the amplitude of the input signal to get distortion less output.
Note down the output amplitude.
3. Vary the DRB until the output amplitude becomes half of its previous value. The
corresponding DRB value gives the output impedance.
Circuit to find input impedance ( Zi ) :
Circuit to find output impedance ( Zo ) :
Ideal Graph :
Gain dB
3dB
Band width
f in Hz
f L f H
f L = Lower cutoff frequency f H = Higher cutoff frequency
Result:
1. Quiescent point : VCE = ____ V, IC = _____ mA
2. Voltage Gain ( AV ) = __________ ( in mid band region )
3. Bandwidth (BW) = ___________ Hz
4. figure of merit ( FM = AV * BW ) = ____________ Hz
5. Input impedance (Zi) = ____________, Output Impedance (Zo) = __________
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3b) Circuit Diagram :
Design :
Given VDD = 10V, VGS(off) = -4V IDSS (max) = 12mA RG = 2 M
Formulae
ID = IDSS.(1 – VGS / VGS (off))2 -------------------------------------(1)
When VG = 0, Then VS = -VGS Applying KVL to output circuit
But VS = ID . RS VDD = ID . RD + VDS + ID .RS
When VG = 0, ID = IDSS RD = (10 – 5 – 4.6 x 10-3 x 330) / 4.6 x 10-3
VS = IDSS.RS RD = 756
IDSS.RS = -VGS (off) Choose RD = 820
RS = -(-4) / 12mA = 333 XCS < < RS
Choose RS = 330 XCS = RS / 10
From (1) 1 / ( 2 f CS ) = 470 / 10 Let f = 100 Hz
ID = IDSS.(1 – ID.RS / VGS (off))2 CS = 33 F Choose CS = 47 F
ID = IDSS.(1 + ID2.RS
2 / 16 - ID.RS /2) Choose CC1 = CC2 = 0.1 F
ID = 12 x 10-3 x (1 + ID2.3302 / 16 - ID.330 /2)
81.675ID2 - 2.98ID +12 x 10-3 = 0
ID = 4.6 mA or ID = 31.9 mA
Since ID cannot be greater than IDSS, Choose ID = 4.6 mA
Assume VDS = 50 % VDD
VDS = 5V
G
D
S
BFW 10
Substrate
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Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 16
3b. RC Coupled Single Stage FET Amplifier
Aim: To conduct an experiment to plot the frequency response of an RC coupled FET
amplifier and to find the half power points, bandwidth, input impedance, output impedance
Apparatus Required:
Sl.
No. Particulars Range Quantity
1. FET BFW 10 - 01
2. Resistors & Capacitors As per design -
3. CRO Probes - 3 Set
4. Multi meter - 01
5. DRB - 01
6. Spring board and connecting wires - -
Theory:
An amplifier is a circuit which increases the voltage, current or power level of i/p
signal where the frequency is maintained constant from o/p to i/p signal. In FET amplifier the
output current (ID) is a function of input voltage VGS. That is as VGS varies the drain
current varies. VGS varies as input signal varies in turn the drain current varies hence
amplification takes place.
In RC coupled FET amplifier RD and RS are selected in such a way that FET
operates in active region and the operating point will be in the middle of active region.
Coupling capacitors CC1 and CC2 are used to block dc current flow through load and the
source. The source by-pass capacitor CS is connected to avoid negative feedback.
An amplifier in which resistance-capacitance coupling is employed between stages
and at the input and output point of the circuit is known as RC coupled amplifier. A capacitor
provides a path for signal currents between stages, with resistors connected from each side of
the capacitor to the power supply or to ground.
Procedure:
1. Components / Equipment are tested for their good working condition.
2. Connections are made as shown in the circuit diagram.
3. By keeping the voltage knobs in minimum position and current knob in maximum
position switch on the power supply.
4. By disconnecting the AC source measure the quiescent point (VDS and ID = VRD / RD)
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5. Connect the AC source. Keeping the frequency of the AC source in mid band region
(say 10 kHz) adjust the amplitude to get the distortion less output. Note down the
amplitude of the input signal.
6. Keeping the input amplitude constant, Vary the frequency in suitable steps and note
down the corresponding output amplitude.
7. Calculate AV and gain in decibels. Plot a graph of frequency Vs gain in dB. From the
graph calculate f L, f H and band width.
8. Calculate figure of merit.
To find the input impedance ( Zi ) :
1. Connections are made as shown in the diagram.
2. Keeping the DRB in its minimum position, apply input signal at mid band frequency
(say 10 kHz) and adjust the amplitude of the input signal to get distortion less output.
Note down the output amplitude.
3. Vary the DRB until the output amplitude becomes half of its previous value. The
corresponding DRB value gives the input impedance.
To find the output impedance ( Zo ) :
1. Connections are made as shown in the diagram.
2. Keeping the DRB in its maximum position, apply input signal at mid band frequency
(say 10 kHz) and adjust the amplitude of the input signal to get distortion less output.
Note down the output amplitude.
3. Vary the DRB until the output amplitude becomes half of its previous value. The
corresponding DRB value gives the output impedance.
Circuit to find input impedance ( Zi ) :
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Circuit to find output impedance ( Zo ) :
Ideal Graph :
Gain dB
3dB
Band width
f in Hz
f L f H
f L = Lower cutoff frequency f H = Higher cutoff frequency
Tabular Column: Vi = ___________ V
F in Hz Vo in Volt AV = Vo / Vi Gain in dB = 20*log
AV
Result:
1. Quiescent point : VDS = ____ V, ID = _____ mA, VGS = ____________ V
2. Voltage Gain ( AV ) = __________ ( in mid band region )
3. Bandwidth (BW) = ___________ Hz
4. figure of merit ( FM = AV * BW ) = ____________ Hz
5. Input impedance (Zi) = ____________, Output Impedance (Zo) = __________
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Half Adder:
a) Half Adder using Basic gates
b) Half Adder using NAND Gates
Truth Table
A B SUM
(S)
CARRY
(C)
0 0 0 0
0 1 1 0
1 0 1 0
1 1 0 1
A
B S= AB
C= AB
A
B
S=AB
C=AB
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Experiment No. : 4 Date: ___/____/_______
Realization of half/Full adder and Half/Full Subtractors using logic gates
Aim: (i) To realize half/full adder using Logic gates & NAND gates
(ii) To realize half/full Subtractor using Logic gates & NAND gates Components Required:
Theory: Half-Adder: A combinational logic circuit that performs the addition of two
data bits, A and B, is called a half-adder. Addition will result in two output
bits; one of which is the sum bit S, and the other is the carry bit, C. The
Boolean functions describing the half-adder are: S =AB
C = A.B Full-Adder: The half-adder does not take the carry bit from its previous
stage into account. This carry bit from its previous stage is called carry-in
bit. A combinational logic circuit that adds two data bits, A and B, and a
carry-in bit,Cin,is called a full-adder. The Boolean functions describing the
full-adder are:
S = A B Cin
C = A.B+ Cin (A B) Half Subtractor: Subtracting a single-bit binary value B from another A
(i.e. A -B) produces a difference bit D and a borrow out bit Br. This
operation is called half subtraction and the circuit to realize it is called a
half subtractor. The Boolean functions describing the half-Subtractor are:
D =A B
Br= A’.B Full Subtractor: Subtracting two single-bit binary values, B, Cin from a
single-bit value A produces a difference bit D and a borrow out Br bit. This
is called full subtraction. The Boolean functions describing the full-
subtractor are: D = A B Cin, Br= A’.B + A’.Cin + B.Cin
Procedure:
Sl no Particulars Quantity
1 IC 7400 3
2 7404,7486,7408,7432 1
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1. Verify that the gates are working.
2. Make the connections as per the circuit diagram for the half adder
circuit, on the trainer kit.
3. Switch on the VCC power supply and apply the various combinations of
the inputs according to the respective truth tables. 4. Verify that the outputs are according to the expected results.
5. Repeat the procedure for the full adder circuit, the half subtractor and
full subtractor circuits. 6. Verify that the sum/difference and carry/borrow bits are according to
the expected values.
FULL ADDER:
a) Full Adder using Basic Gates
b) Full Adder using NAND Gates only
B S= ABC
C= AB+C(AB)
A
C
A
B
C
S= ABC
C= AB+C(AB)
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Truth Table:
SUM= S= ABC
C= AB+C(AB)
Half Subtractor:
a. Half Subtractor using Basic gates
b. Half Subtractor using NAND Gates
A B C Sum Carry
0 0 0 0 0
0 0 1 1 0
0 1 0 1 0
0 1 1 0 1
1 0 0 1 0
1 0 1 0 1
1 1 0 0 1
1 1 1 1 1
A
B
D=AB
A
B D= AB
Bo= AB
C= A B
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Truth Table
Full Subtractor:
c. Full Subtractor using Basic Gates
d. Full Subtractor using Nand gates
Truth Table:
Diff= ABC
B0 = A B+C(AB)
A B Diff(D) Borrow
(B)
0 0 0 0
0 1 1 1
1 0 1 0
1 1 0 0
A B C Diff Borrow
0 0 0 0 0
0 0 1 1 1
0 1 0 1 1
0 1 1 0 1
1 0 0 1 0
1 0 1 0 0
1 1 0 0 0
1 1 1 1 1
A
B D= A B C
Bo= A B+C(AB)
C
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Circuit Diagram :
Design :
Given, VCE = 5 V, IC = 2 mA and (Assume = 100)
VCC = 2VCE = 2 X 5 = 10 V
Let VRE = 10% VCC = 1 V
RE = VRE / ( IC + IB )
IB = IC / = 2mA / 100 = 20 A
RE = 1 / ( 2m + 20 ) = 495
Choose RE = 470
Apply KVL to collector loop
VCC – IC RC – VCE – VE = 0
RC = ( VCC – VCE – VE ) / IC = ( 10 – 5 – 1 ) / 2 m
RC = 2 K Choose RC = 1.8 K
Let IR1 = 10 IB = 10 X 20 A = 200 A
VR2 = VBE + VE = 0.6 + 1 = 1.6 V ( Since transistor is silicon make VBE = 0.6 V )
R2 = VR1 / ( IR1 – IB ) = 1.6 / ( 200 A - 20 A )
R2 = 8.8 K Choose R2 = 8.2 K
R1 = ( VCC – VR2 ) / IR1 = ( 10 – 1.6 ) / 200 A
R1 = 42 K Choose R1 = 47 K
t
Vo
T
fo = 1 / T Hz
C
B
E
SL100
or
CL100
0.1 F
0.1 F
R3 = R-Ri
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Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 26
Experiment No. : 5 Date: ___/____/_______
RC Phase Shift Oscillator
Aim: To design and test an RC phase shift oscillator for the given frequency of oscillations.
Apparatus Required:
Sl.
No. Particulars Range Quantity
1. Transistor SL 100 - 01
2. Resistors & Capacitors As per design -
3. CRO Probes - 3 Set
4. Multi meter - 01
5. DRB - 01
6. Spring board and connecting wires - -
Theory:
An oscillator is an electronic circuit that produces a repetitive electronic signal, often
a sine wave or a square wave. RC-phase shift oscillator is used generally at low frequencies
(Audio frequency). It consists of a CE amplifier as basic amplifier circuit and three identical
RC networks for feed back, each section of RC network introduces a phase shift of 60 and
the total phase shift by feedback network is 180. The CE amplifier introduces 180 phase
shift hence the overall phase shift is 360. The feed back factor for an RC phase shift
oscillator is 1/29, hence the gain of amplifier (A) should be 29 to satisfy Barkhausen
criteria.
The Barkhausen criteria states that in a positive feedback amplifier to obtain sustained
oscillations, the overall loop gain must be unity ( 1 ) and the overall phase shift must be 0 or
360.
When the power supply is switched on, due to random motion of electrons in passive
components like resistor, capacitor a noise voltage of different frequencies will be developed
at the collector terminal of transistor, out of these the designed frequency signal is fed back to
the amplifier by the feed back network and the process repeats to give suitable oscillation at
output terminal
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Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 27
XCE < < RE
XCE = RE / 10
1 / ( 2 f CE ) = 470 / 10 Let f = 100 Hz
CE = 33 F Choose CE = 47 F
Choose CC1 = CC2 = 0.1 F
Tank Circuit : Assume fo = 1 kHz
f o = 1/[(2 x x R x C (6+4k)0.5]
where k = Rc / R, and Ri = R1 || R2 || hie
4k+23+29/k ≤ hfe
Assume hfe = β = 100
Therefore 4k+23+29/k = 100
4k2+23k+29 = 100
4k2 – 77k + 29 = 0
k = 18.865 or 0.385
if k = 18.865 , Rc / R = 18.865
R is very small. Therefore proper oscillations are not obtained
Choosing k = 0.385
Rc = 1.8 k
R = 4.675 k
Choose R = 4.7 k
C =1/[2 x x fo x R (6+4 x 0.385)0.5]
C = 0.012 µF
Choose C = 0.01 µF
Ri = 8.2K || 47K || 1.1K
Ri = 0.9 k
R3 = R – Ri
R3 = 3.8 k
Procedure :
1. Components / equipment are tested for their good working condition.
2. Connections are made as shown in the diagram
3. The quiescent point of the amplifier is verified for the designed value.
4. Observe the output wave form on CRO and measure the frequency.
5. Verify the frequency with the designed value.
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Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 28
Result:
Q Point: VCE = _____ V, Ic = ______ mA
fo Theoretical = _____________ Hz
fo Practical = _______________ Hz
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Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 29
1. 4-BIT BINARY ADDER
Example: 7+2=11 (1001) • 7 is realized at A3 A2 A1 A0 = 0111 • 2 is realized at B3 B2 B1 B0 = 0010
Sum = 1001 Procedure:
1. Check all the components for their working. 2. Insert the appropriate IC into the IC base. 3. Make connections as shown in the circuit diagram. 4. Apply augend and addend bits on A and B and cin=0. 5. Verify the results and observe the output of ADDER CIRCUIT
Circuit :
2. 4-Bit Binary Subtractor.
(i) 4 bit subtraction operation using 7483 for A>B and Cin=1
Example: 8 – 3 = 5 (0101)
• 8 is realized at A3 A2 A1 A0 = 1000
• 3 is realized at B3 B2 B1 B0 through X-OR gates = 0011
• Output of X-OR gate is 1’s complement = 1100
• 2’s Complement can be obtained by adding Cin = 1
Therefore Cin = 1
A3 A2 A1 A0 = 1 0 0 0
B3 B2 B1 B0 = 1 1 0 0
S3 S2 S1 S0 = 0 1 0 1 Cout = 1 (Ignored)
Exercise: (i) 9-12=-3 (ii) 15-9=6 (iii) 8+6=14 (iv) 5+10=15
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[Electronics Lab : 17 EEL 38]
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 30
Experiment No. : 6 Date: ___/____/_______
Realization of parallel adder/Subtractors using 7483 chip- BCD to Excess-3
code conversion & Vice –Versa
6 a) parallel adder/Subtractors using 7483
Aim: To design and set up the following circuit using IC 7483.
i) A 4-bit binary parallel adder.
ii) A 4-bit binary parallel subtractor. Components Required: IC 7483, IC 7486, Trainer kit, etc
Theory:
The Full adder can add single-digit binary numbers and carries. The
largest sum that can be obtained using a full adder is 112. Parallel adders
can add multiple-digit numbers. If full adders are placed in parallel, we can
add two- or four-digit numbers or any other size desired. Figure below uses
STANDARD SYMBOLS to show a parallel adder capable of adding two, two-
digit binary numbers The addend would be on A inputs, and the augend on
the B inputs.
To add four bits need four full adders arranged in parallel. IC 7483 is a 4-
bit parallel adder is used.
MSB LSB
INPUTS Cin
A3 A2 A1 A0
B3 B2 B1 B0
OUTPUT Cout S3 S2 S1 S0
ii) 4 bit subtraction operation using 7483 for A<B and Cin=1
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Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 31
Example: 14 – 15 = -1 (1111)
• 14 is realized at A3 A2 A1 A0 = 1110
• 15 is realized at B3 B2 B1 B0 through X-OR gates = 1111
• Output of X-OR gate is 1’s complement of 15 = 0000
• 2’s Complement can be obtained by adding Cin = 1
Therefore Cin = 1
A3 A2 A1 A0 = 1 1 1 0
B3 B2 B1 B0 = 0 0 0 0
S3 S2 S1 S0 = 1 1 1 1 since the most significant bit of the result is 1, this is a negative number, so
form the two's complement of (1111)=0001(-1)
Procedure:
1. Check all the components for their working. 2. Insert the appropriate IC into the IC base. 3. Make connections as shown in the circuit diagram. 4. Apply Minuend and subtrahend bits on A and B and cin=1. 5. Verify the results and observe the outputs.
Circuit:
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Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 32
Experiment 6(b): CODE CONVERTERS. Aim: To design and realize the following using IC 7483.
(i) Excess-3 to BCD Code conversion and vice-versa (ii) Realization of Binary to Gray code conversion and vice versa
Components Required: IC 7483, IC 7486, Patch Cords & IC Trainer Kit.
Theory:
Code converter is a combinational circuit that translates the input
code word into a new corresponding word. The excess-3 code digit is
obtained by adding three to the corresponding BCD digit. To Construct a
BCD-to-excess-3-code converter with a 4-bit adder feed BCD code to the 4-
bit adder as the first operand and then feed constant 3 as the second
operand. The output is the corresponding excess-3 code. To make it work as a excess-3 to BCD converter, we feed excess-3 code as
the first operand and then feed 2's complement of 3 as the second operand.
The output is the BCD code.
Excess-3-code to BCD: Truth Table:
Excess-3 inputs BCD outputs
E3 E2 E1 E0 B3 B2 B1 B0
0 0 0 0 0 0 0 0
0 1 0 0 0 0 0 1
0 1 0 1 0 0 1 0
0 1 1 0 0 0 1 1
0 1 1 1 0 1 0 0
1 0 0 0 0 1 0 1
1 0 0 1 0 1 1 0
1 0 1 0 0 1 1 1
1 0 1 1 1 0 0 0
1 1 0 0 1 0 0 1
Hint: Add +3 to 4digit binary numbers from 0 to 9, other cases as don’t
cares
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Procedure: 1. Check all the components for their working.
2. Insert the appropriate IC into the IC base.
3. Make connections as shown in the circuit diagram.
4. Apply Excess-3-code code as first operand (A) and binary 3 as second
operand(B) and Cin=1 for realizing Excess-3-code to BCD.
Circuit:
BCD to Excess-3-code: Truth Table:
BCD inputs Excess-3 outputs
B3 B2 B1 B0 E3 E2 E1 E0
0 0 0 0 0 0 0 0
0 0 0 1 0 1 0 0
0 0 1 0 0 1 0 1
0 0 1 1 0 1 1 0
0 1 0 0 0 1 1 1
0 1 0 1 1 0 0 0
0 1 1 0 1 0 0 1
0 1 1 1 1 0 1 0
1 0 0 0 1 0 1 1
1 0 0 1 1 1 0 0
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Procedure: 1. Check all the components for their working. 2. Insert the appropriate IC into the IC base. 3. Make connections as shown in the circuit diagram. 4 Apply BCD code as first operand(A) and binary 3 as second operand(B) and
cin=0 for Realizing BCD-to-Excess-3-code:
Circuit :
RESULT:
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[Electronics Lab : 17 EEL 38]
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 35
Circuit Diagram: Without boot strapping
Design:
For Q(VCE,IC)=5V,2mA
Select SL100, β=100,VCC=10V
Composite hFE = hFE1 *x hFE2=50X100=5000
RE:
IB=IC/Hfe=2mA/5000=0.4µA IE=IC=2mA
KI
VVRE
E
CECC 5.22
510
Choose RE=2.2KΩ
R3: Choose R3=10KΩ
VE=2.2X2=4.4V V’B=VBE1+VBE2+VE=0.7+0.7+4.4=5.8V
VB=V’B+IBR3=5.804V
I1=I2+IB
R2: Choose R2=1KΩ
R1: I2=VB\R2=5.804mA
I1=5.804mA
C
B
E
SL100
or
CL100
2019-20
[Electronics Lab : 17 EEL 38]
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 36
Experiment No. :7 Date: ___/____/_______
Darlington Emitter Follower
Aim : To conduct an experiment to plot the frequency response of an Darlington emitter
follower amplifier with and without bootstrapping and to find the input impedance, output
impedance and the voltage gain.
Apparatus Required :
Sl.
No. Particulars Range Quantity
1. Transistor SL 100 and 2N3055 - 1 each
2. Resistors & Capacitors As per design -
3. Multi meter - 01
4. CRO probes - 3 set
5. DRB - 01
6. Spring board and connecting wires - -
Theory :
When high input impedance and low output impedance requirements are to be met the
natural choice is common collector configuration the common collector configuration of
transistor has high input impedance, low output impedance and high current gain although no
phase inversion. The common collector transistor amplifies is termed as emitter follower for
the simple reason that the o/p voltage follows the input voltage ( AV 1 ). The important
application of emitter follower is as buffer amplifier for impedance matching. A single stage
emitter follower provides an i/p impedance of 500 K. But for the requirement of i/p
impedance beyond 500 K we employ Darlington emitter follower. The voltage gain of
Darlington Emitter Follower is less than but very nearly equal to unity. The coupling of the
two stages of emitter follower amplifier, this cascaded connection of two emitter follower is
called Darlington connections. In this connection, since two stages of transistor are connected
it improves the current gain and input resistance of the circuit. In Darlington connections of
two transistor emitter of the first transistor is directly connected to the base of the second
transistor. The leakage current of the first transistor is amplified by the second transistor and
overall leakage current may be high which is not desired. For further high i/p impedance
requirement we employ bootstrapping. Bootstrap circuit is an arrangement of
components used to boost the input impedance of a circuit by using a small amount of
positive feedback, usually over two stages
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Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 37
780804.5
804.510
1
1I
VVR BCC
Choose R1=680Ω (+100Ω in series optional)
Boot strap capacitor CB should be large, choose CB=10µf
VCC=10V, R1=680 , R2=1k , R3=10k , RE =2.2k ,C1=C3=0.1μF
CB=10 μF
Circuit Diagram: With boot strapping
Circuit to find input impedance ( Zi ) :
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Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 38
Circuit to find output impedance ( Zo ) :
Procedure : ( With and without bootstrapping )
1. Check all the components and equipments for their good working condition.
2. Connections are made as shown in the circuit diagram.
3. By keeping the voltage knobs in minimum position and current knob in maximum
position switch on the power supply.
4. By disconnecting the AC source measure the quiescent point
(VEC2 and IE2 = VRE / RE)
To find frequency response :
1. Connect the AC source. Keeping the frequency of the Ac source in mid band region
(say 10 kHz) adjust the amplitude to get the distortion less output. Note down the
amplitude of the input signal.
2. Keeping the input amplitude constant, Vary the frequency in suitable steps and note
down the corresponding output amplitude.
3. Calculate AV and gain in decibels. Plot a graph of frequency Vs gain in dB. From the
graph calculate f L, f H and band width.
4. Calculate figure of merit.
To find the input impedance ( Zi ) :
1. Connections are made as shown in the diagram.
2. Keeping the DRB in its minimum position, apply input signal at mid band frequency
(say 10kHz) and adjust the amplitude of the input signal to get distortion less output.
Note down the output amplitude.
3. Vary the DRB until the output amplitude becomes half of its previous value. The
corresponding DRB value gives the input impedance.
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To find the output impedance ( Zo ) :
1. Connections are made as shown in the diagram.
2. Keeping the DRB in its maximum position, apply input signal at mid band frequency
(say 10kHz) and adjust the amplitude of the input signal to get distortion less output.
Note down the output amplitude.
3. Vary the DRB until the output amplitude becomes half of its previous value. The
corresponding DRB value gives the output impedance.
Tabular Column : Without bootstrapping Vi = ___________ V
F in Hz Vo in Volt AV = Vo / Vi Gain in dB = 20*log AV
Ideal Graph :
Gain dB fL fH f in Hz
3dB
Band width
f L = Lower cutoff frequency f H = Higher cutoff frequency
2019-20
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Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 40
With bootstrapping Circuit: Vi = ___________ V
F in Hz Vo in Volt AV = Vo / Vi Gain in dB = 20*log AV
Result:
Without bootstrapping
1. Quiescent point : VEC2 = ____ V, IE = _____ mA,
2. Voltage Gain ( AV ) = __________ ( in mid band region )
3. Bandwidth (BW) = ___________ HZ
4. figure of merit ( FM = AV * BW ) = ____________ Hz
5. Input impedance (Zi) = ____________, Output Impedance (Zo) = __________
With bootstrapping
1. Quiescent point : VEC2 = ____ V, IE = _____ mA,
2. Voltage Gain ( AV ) = __________ ( in mid band region )
3. Bandwidth (BW) = ___________ HZ
4. figure of merit ( FM = AV * BW ) = __________
5. Input impedance (Zi) = ____________,
Output Impedance (Zo) = __________
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Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 41
1.Ring Counter:
Circuit
Truth Table
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Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 42
Experiment No. :8 Date: ___/____/_______
Design and testing Ring counter/Johnson counter.
Aim: To design and study the operation of a ring counter and a Johnson
Counter.
Components required: IC 7495, IC 7404, Patch Cards & IC Trainer Kit.
Theory:
A ring counter is a circular shift register which is initiated such that
only one of its flip-flops is the state one while others are in their zero states.
A ring counter is a Shift Register with the output of the last one connected to
the input of the first, that is, in a ring. Typically, a pattern consisting of a
single bit is circulated so the state repeats every n clock cycles if n flip-flops are
used. It can be used as a cycle counter of n states.
A Johnson counter (or switchtail ring counter, twisted-ring counter,
walking-ring counter, or Moebius counter) is a modified ring counter, where the
output from the last stage is inverted and fed back as input to the first
stage. The register cycles through a sequence of bit-patterns, whose length is
equal to twice the length of the shift register, continuing indefinitely. These
counters find specialist applications, including those similar to the decade
counter, digital-to-analog conversion, etc. They can be implemented easily
using D- or JK-type flip-flops.
Procedure:
1. Make the connections as shown in the respective circuit diagram.
2. Apply an initial input (1000) at the A, B, C, D pins respectively.
3. Keep Select Mode = HIGH (1) and apply one clock pulse.
4. Next, Select Mode = LOW (0) to switch to serial mode and apply clock pulses.
5. Observe the output after each clock pulse, record the observations and verify
that they match the expected outputs from the truth table.
6. Repeat the same procedure as above for the Johnson Counter circuit and
verify its operation
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2. JHONSON COUNTER
Truth Table:
Circuit:
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Karnaugh Map:
Circuit:
Result:
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Experiment No. : 9 Date: ___/____/_______
Design and testing of Sequence generator.
Aim: To design and study the operation of a Sequence Generator.
Components required: IC 7495, IC 7486, Patch Cards & IC Trainer Kit.
Procedure:
1. Truth table is constructed for the given sequence, and Karnaugh maps are
drawn in order to obtain a simplified Boolean expression for the circuit.
2. Connections are made as shown in the circuit diagram.
3. Mode M is set to LOW (0), and clock pulses are fed through Clk 1 (pin 9).
4. Clock pulses are applied at CLK 1 and the output values are noted, and
checked against the expected values from the truth table.
5.The functioning of the circuit as a sequence generator is verified.
Truth Table
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Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 47
Binary to Gray code Realization using Nand Gates
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Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 48
Experiment No. : 10 Date: ___/____/_______
Binary to Gray code conversion and vice versa
Components Required: IC 7486, IC 7400and IC 7408. Theory:
Binary to gray code conversion is a very simple process. There are
several steps to do this types of conversions. Steps given below elaborate on
the idea on this type of conversion. (1) The M.S.B. of the gray code will be exactly equal to the first bit of the
given binary number. (2) Now the second bit of the code will be exclusive-or of the first and second
bit of the given binary number, i.e if both the bits are same the result will be
0 and if they are different the result will be 1. (3)The third bit of gray code will be equal to the exclusive -or of the second
and third bit of the given binary number. Thus the Binary to gray code
conversion goes on. One example given below can make your idea clear on
this type of conversion.
Gray code to binary conversion is again very simple and easy process. Following steps can make your idea clear on this type of conversions. (1) The M.S.B of the binary number will be equal to the M.S.B of the given
gray code. (2) Now if the second gray bit is 0 the second binary bit will be same as the
previous or the first bit. If the gray bit is 1 the second binary bit will alter. If
it was 1 it will be 0 and if it was 0 it will be 1. (3) This step is continued for all the bits to do Gray code to binary
conversion.
Hint:
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Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 49
Karaungh maps: (i)Realization using Basic Gates:
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Procedure:
1. Verify that the gates are working. 2. Write the proper truth table for the given Binary to Gray /Gray to binary
converter
3. Draw Karnaugh maps for each bit of output. Simplify the Karnaugh maps to get
simplified Boolean Expressions. 4. Make connections on the trainer kit as shown in the circuit diagram for the Binary to
Gray /Gray to Binary converter. 5. Check the outputs for the corresponding inputs.
BINARY TO GRAY CONVERSION: Truth Table:
Binary inputs Gray outputs
B3 B2 B1 B0 G3 G2 G1 G0
0 0 0 0 0 0 0 0
0 0 0 1 0 0 0 1
0 0 1 0 0 0 1 1
0 0 1 1 0 0 1 0
0 1 0 0 0 1 1 0
0 1 0 1 0 1 1 1
0 1 1 0 0 1 0 1
0 1 1 1 0 1 0 0
1 0 0 0 1 1 0 0
1 0 0 1 1 1 0 1
1 0 1 0 1 1 1 1
1 0 1 1 1 1 1 0
1 1 0 0 1 0 1 0
1 1 0 1 1 0 1 1
1 1 1 0 1 0 0 1
1 1 1 1 1 0 0 0
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GRAY TO BINARY CONVERSION : Truth Table:
Gray
inputs Binary outputs
G3 G2 G1 G0 B3 B2 B1 B0
0 0 0 0 0 0 0 0
0 0 0 1 0 0 0 1
0 0 1 1 0 0 1 0
0 0 1 0 0 0 1 1
0 1 1 0 0 1 0 0
0 1 1 1 0 1 0 1
0 1 0 1 0 1 1 0
0 1 0 0 0 1 1 1
1 1 0 0 1 0 0 0
1 1 0 1 1 0 0 1
1 1 1 1 1 0 1 0
1 1 1 0 1 0 1 1
1 0 1 0 1 1 0 0
1 0 1 1 1 1 0 1
1 0 0 1 1 1 1 0
1 0 0 0 1 1 1 1
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Karnaugh maps:
(i)Realization using Basic Gates:
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d) Realization using Nand Gates:
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1. 3 Bit Asynchronous Up Counter
Truth Table: Circuit:
Clock
QC
QB
QA
0
0
0
0
1
0
0
1
2
0
1
0
3
0
1
1
4
1
0
0
5
1
0
1
6
1
1
0
7
1
1
1
8
0
0
0
9
0
0
1
Wave Forms:
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Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 56
Experiment No. : 11 Date: ___/____/_______
Realization of 3 bit counters as a sequential circuit and MOD – N counter
design using 7476,7490, 74192, 74193.
Experiment 11(a): ASYNCHRONOUS COUNTERS
Aim: To design and test 3-bit binary asynchronous up/down counter using flip-fop IC 7476 for the given sequence. Components required: IC 7476,patch cards,trainer kit etc. Theory:
An asynchronous (ripple) counter is a single JK-type flip-flop, with its J (data) input fed from its own inverted output. This circuit can store one bit, and hence can count from zero to one before it overflows (starts over from 0). Notice that this creates a new clock with a 50% duty cycle at exactly half the frequency of the input clock. If this output is then used as the clock signal for a similarly arranged D flip-flop (remembering to invert the output to the input), one will get another 1 bit counter that counts half as fast. Putting them together yields a two-bit counter: We can continue to add additional flip-flops, always inverting the output to its own input, and using the output from the previous flip-flop as the clock signal. The result is called a ripple counter,
which can count to 2n − 1 where n is the number of bits (flip-flop stages) in the counter
PROCEDURE: 1. Check all the components for their working. 2. Make connections as shown in the circuit diagram. 3. Clock pulses are applied one by one at the clock input and output is observed at QA,QB and QC. 4. Verify the Truth Table and observe the outputs.
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2. 3 Bit Asynchronous Down Counter
Truth Table: Circuit:
Wave Forms:
Clock
QC
QB
QA
0
1
1
1
1
1
1
0
2
1
0
1
3
1
0
0
4
0
1
1
5
0
1
0
6
0
0
1
7
0
0
0
8
1
1
1
9
1
1
0
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3. Mod 5 Up Counter:
Truth Table Waveforms:
Clock
QC
QB
QA
0
0
0
0
1
0
0
1
2
0
1
0
3
0
1
1
4
1
0
0
5
0
0
0
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4. Mod 4 Down Counter:
Truth Table: Wave forms
Clock
QC
QB
QA
0
1
1
1
1
1
1
0
2
1
0
1
3
1
0
0
4
1
1
1
2019-20
[Electronics Lab : 17 EEL 38]
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 60
Circuit:
Waveforms:
2019-20
[Electronics Lab : 17 EEL 38]
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 61
Experiment 11(b): SYNCHRONOUS COUNTERS Aim: To design and test a 3 bit synchronous counter using 7476
Components required: IC7476,7408,Patch cards,trainer kit ,etc.
Theory:
In synchronous counters, the clock inputs of all the flip-flops are
connected together and are triggered by the input pulses. Thus, all the flip-
flops change state simultaneously (in parallel).
A synchronous binary counter counts from 0 to 2N-1, where N is the number of bits/flip-flops in the counter. Each flip-flop is used to represent one
bit. The flip-flop in the lowest-order position is complemented with every clock
pulse and a flip-flop in any other position is complemented on the next clock
pulse provided all the bits in the lower-order positions are equal to 1.
Procedure:
1. Check all the components for their working.
2. Make connections as shown in the circuit diagram.
3. Clock pulses are applied one by one at the clock input and output is
observed at QA,QB and QC.
4. Verify the Truth Table and observe the outputs.
Truth Table:
Clock
QC
QB
QA
0
0
0
0
1
0
0
1
2
0
1
0
3
0
1
1
4
1
0
0
5
1
0
1
6
1
1
0
7
1
1
1
2019-20
[Electronics Lab : 17 EEL 38]
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 62
1. MOD 10 Counter: Truth Table: Circuit:
Clock
QD
QC
QB
QA
0
0
0
0
0
1
0
0
0
1
2
0
0
1
0
3
0
0
1
1
4
0
1
0
0
5
0
1
0
1
6
0
1
1
0
7
0
1
1
1
8
1
0
0
0
9
1
0
0
1
10
0
0
0
0
2019-20
[Electronics Lab : 17 EEL 38]
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 63
Experiment 11(c): DECADE COUNTERS Aim: To rig up Mod N counter using IC 7490.
Components required: IC7490,Patch cards,trainer kit ,etc.
Procedure:
1. Check all the components for their working.
2. Make connections as shown in the circuit diagram.
3. Clock pulses are applied one by one at the clock input and output is
observed at QA,QB ,QC and QD
4. Verify the Truth Table and observe the outputs.
Wave forms
5 12 9 8 11
14
10 1 2 3 6 7
Mod 2 Mod5
QA
QB
QC
QD
Vcc
I/p A
Clk
I/p B R1 R2 S1 S2
2019-20
[Electronics Lab : 17 EEL 38]
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 64
2. MOD 8 Counter:
Truth Table: Circuit:
Clock
QD
QC
QB
QA
0
0
0
0
0
1
0
0
0
1
2
0
0
1
0
3
0
0
1
1
4
0
1
0
0
5
0
1
0
1
6
0
1
1
0
7
0
1
1
1
8
0
0
0
0
Waveforms:
RESULT:
2019-20
[Electronics Lab : 17 EEL 38]
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 65
Experiment 12(d): PROGRAMMABLE 4 BIT SYNCHRONOUS UP/DOWN COUNTERS
Aim: To rig up Mod N Synchronous up/down counter using IC 74193& 74192
Components required: IC74193,7400,7432,74192,Patch cards,trainer kit ,etc.
Procedure:
1. Check all the components for their working.
2. Make connections as shown in the circuit diagram.
3. The preset value is made available at the data inputs C,B and A.
4. The load pin is made low so that the preset value appear at QA,QB ,QC andQD.
5. Connect the output of the gate to the load input.
6. Clock pulses are applied and truth table are verified.
1.Count from 3 to 8:
Truth table: Circuit
Clk
QD
QC
QB
QA
0
0
0
1
1
1
0
1
0
0
2
0
1
0
1
3
0
1
1
0
4
0
1
1
1
5
1
0
0
0
6
0
0
1
1
2019-20
[Electronics Lab : 17 EEL 38]
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 66
2.Count from 12 to 5
Circuit
Truth table:
Preset value=12, N=8
Result:
Clk
QD
QC
QB
QA
0
1
1
0
0
1
1
0
1
1
2
1
0
1
0
3
1
0
0
1
4
1
0
0
0
5
0
1
1
1
6
0
1
1
0
7
0
1
0
1
8
1
1
0
0
2019-20
[Electronics Lab : 17 EEL 38]
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 67
C
B
E
BC 107
Or
SL100
2019-20
[Electronics Lab : 17 EEL 38]
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 68
Experiment No. : 12 Date: ___/____/_______
Static Transistor characteristics for CE, CB and CC modes and
determination of h parameters
12. a) To study the input and output characteristics of a transistor in Common
Base Configuration.
S.No. Name Quantity
1 Transistor BC 107 1
2 Resistors (1K) 2
3 Bread board 1
4 Dual DC Regulated Power supply (0 – 30 V) 1
5 Digital Ammeters ( 0 – 200 mA) 2
6 Digital Voltmeter (0-20V) 2
Operation:Bipolar Junction Transistor (BJT) is a three terminal emitter, base, collector)
semiconductor device. There are two types of BJTs, namely NPN and PNP. It consists of two
PN junctions, namely emitter junction and collector junction.The basic circuit diagram for
studying input characteristics is shown in the circuit diagram. The input is applied between
emitter and base, the output is taken between collector and base. Here base of the transistor is
common to both input and output and hence the name is Common Base Configuration.
Input characteristics are obtained between the input current and input voltage at constant
output voltage. It is plotted between VEE and IE at constant VCB in CB configuration.
Output characteristics are obtained between the output voltage and output current at constant
input current. It is plotted between VCB and IC at constant IE in CB configuration.
Procedure:
Input Characteristics:
1. Connect the circuit as shown in the circuit diagram.
2. Keep output voltage VCB = 0V by varying VCC.
3. Varying VEE gradually, note down emitter current IE and emitter-base voltage(VEE).
4. Step size is not fixed because of nonlinear curve. Initially vary VEE in steps of 0.1 V.
Once the current starts increasing vary VEE in steps of 1V up to 12V.
5. Repeat above procedure (step 3) for VCB = 4V
2019-20
[Electronics Lab : 17 EEL 38]
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 69
Output Characteristics:
1. Connect the circuit as shown in the circuit diagram.
2. Keep emitter current IE = 5mA by varying VEE.
3. Varying VCC gradually in steps of 1V up to 12V and note down collector current
IC and collector-base voltage(VCB).
4. Repeat above procedure (step 3) for IE = 10mA
Input characteristics :
VCB = 0V
VEE(Volts) IE (mA)
VCB = 4V
VEE (Volts) IE (mA)
Output characteristics :
IE= 5mA
VCB (Volts) IC (mA)
IE= 10mA
VCB (Volts) IC (mA)
1. Plot the input characteristics for different values of VCB by taking VEE on X-axis
and IE on Y-axis taking VCB as constant parameter.
2019-20
[Electronics Lab : 17 EEL 38]
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 70
2. Plot the output characteristics by taking VCB on X-axis and taking IC on Y-axis
taking IE as a constant parameter
Calculations from Graph:
The h-parameters are to be calculated from the following formulae:
1. Input Characteristics: To obtain input resistance, find VEE and IE for a constant
VCB on one of the input characteristics.
Input impedance = hib = Ri = VEE / IE (VCB = constant)
Reverse voltage gain = hrb = VEB / VCB (IE = constant)
2. Output Characteristics: To obtain output resistance, find IC and VCB at a
constant IE.
Output admitance = hob = 1/Ro = IC / VCB (IE = constant)
Forward current gain = hfb = IC / IE (VCB = constant)
Hint:
1. Input resistance is in the order of tens of ohms since Emitter-Base Junction is forward
biased.
2. Output resistance is in order of hundreds of kilo-ohms since Collector-Base Junction
is reverse biased.
3. Higher is the value of VCB, smaller is the cut in voltage.
4. Increase in the value of IB causes saturation of transistor at small voltages.
Result:
The h-parameters for a transistor in CB configuration are:
a. The Input resistance (hib) __________________ Ohms.
b. The Reverse Voltage Transfer Ratio (hrb) __________________
c. The Output Admittance (hob) __________________ Mhos.
d. The Forward Current gain (hfb) __________________.
2019-20
[Electronics Lab : 17 EEL 38]
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 71
2019-20
[Electronics Lab : 17 EEL 38]
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 72
12. b) To study the input and output characteristics of a transistor in Common Emitter
Configuration.
S.No. Name Quantity
1 Transistor BC 107 1
2 Resistors (1K & 100K) 1 Each
3 Bread board 1
4 Dual DC Regulated Power supply (0 – 30 V) 1
5 Digital Ammeters ( 0 – 200 mA)/ ( 0 – 200 A) 1 Each
6 Digital Voltmeter (0-20V) 2
Operation:
The basic circuit diagram for studying input characteristics is shown in the circuit diagram.
The input is applied between base and emitter, the output is taken between collector and
emitter. Here emitter of the transistor is common to both input and output and hence the name
Common Emitter Configuration.
Input characteristics are obtained between the input current and input voltage at constant
output voltage. It is plotted between VBE and IB at constant VCE in CE configuration.
Output characteristics are obtained between the output voltage and output current at constant
input current. It is plotted between VCE and IC at constant IB in CE configuration.
Procedure:
Input Characteristics:
1. Connect the circuit as shown in the circuit diagram.
2. Keep output voltage VCE = 0V by varying VCC.
3. Varying VBB gradually, note down base current IB and base-emitter voltage VBE.
4. Step size is not fixed because of non linear curve. Initially vary VBB in steps of 0.1V.
Once the current starts increasing vary VBB in steps of 1V up to 12V.
5. Repeat above procedure (step 3) for VCE = 5V.
Output Characteristics:
1. Connect the circuit as shown in the circuit diagram.
2. Keep emitter current IB = 20 A by varying VBB.
3. Varying VCC gradually in steps of 1V up to 12V and note down collector
current IC and Collector-Emitter Voltage (VCE).
4. Repeat above procedure (step 3) for IB = 60µA, 0µA.
2019-20
[Electronics Lab : 17 EEL 38]
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 73
Input characteristics :
VCE= 0V
VBE(Volts) IB(mA)
VCE = 5V
VBE(Volts) IB(mA)
Output characteristics :
IB=0/20µA
VCE (Volts) IC (mA)
IB=60µA
VCE (Volts) IC (mA)
1. Plot the input characteristics by taking VBE on X-axis and IB on Y-axis at a
constant VCE as a constant parameter.
2. Plot the output characteristics by taking VCE on X-axis and taking IC on Y-axis
taking IB as a constant parameter.
Calculations from Graph:
1. Input Characteristics: To obtain input resistance find VBE and IB for a
constant VCE on one of the input characteristics.
Input impedance = hie = Ri = VBE / IB (VCE is constant)
Reverse voltage gain = hre = VEB / VCE (IB = constant)
2. Output Characteristics: To obtain output resistance find IC and VCB at a
constant IB.
2019-20
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 74
Output admittance 1/hoe = Ro = IC / VCE (IB is constant)
Forward current gain = hfe = IC / IB (VCE = constant)
Hint:
1. Medium input and output resistances.
2. Smaller values if VCE, lower the cut-in-voltage.
3. Increase in the value of IE causes saturation of the transistor of an earlier voltage.
Result:
Input and Output characteristics of a Transistor in Common Emitter Configuration are
studied.
The h-parameters for a transistor in CE configuration are:
a. The Input Resistance (hie) _______________Ohms.
b. The Reverse Voltage Gain (hre) _______________.
c. The Output Conductance (hoe) _______________ Mhos.
d. The Forward Current Gain (hfe) _______________.
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 75
Circuit Diagram:
CC Configuration
Tabular Column :
Input Characteristics:
Output Characteristics:
VCC
IB=40µA IB =100µA
VCE IE VCE IE
VBB
VCE=2V VCE=4V
VCB IB VCB IB
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 76
12 c).Input & Output Characteristics of CC Configuration and h-Parameter
calculations
Aim: To study the input and output characteristics of a transistor in Common Collector
Configuration.
Apparatus Required:
Sl.
No. Particulars Range Quantity
1. Transistor BC 107 - 01
3. Resistors 1KΩ,1KΩ 02
4. Multimeter - 01
5. CRO Probes - 2 Set
6 Dual DC Regulated Power supply 0 – 30 V 1
7 Digital Ammeters
0 – 20/200
mA
2
8 Spring board and connecting wires - -
Theory:
In common collector configuration the input current is the base current IB and the
output current is the emitter current IE.
In this configuration collector terminal is common for both input and output signals. This
configuration is also known as emitter follower configuration because the emitter voltage
follows the base voltage. This configuration is mostly used as a buffer. These configurations
are widely used in impedance matching applications because of their high input impedance.
In this configuration the input signal is applied between the base-collector region and the
output is taken from the emitter-collector region. Here the input parameters are VBC and IB
and the output parameters are VEC and IE. The common collector configuration has high input
impedance and low output impedance. The input and output signals are in phase. Here also
the emitter current is equal to the sum of collector current and the base current. The voltage
gain for this circuit is less than unity but it has large current gain because the load resistor in
this circuit receives both the collector and base currents
.
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 77
Characteristic Curves
Common Collector Input Characteristic Curve
Common Collector Output Characteristic Curves
Calculations from Graph:
Vbc= hic Ib+hrcVec
Ie= hfcIb+hocVec
1. Input Characteristics: To obtain input resistance find VBC and IB for a
constant VCE on one of the input characteristics.
Input impedance = hie = Ri = VBC / IB (VCE is constant)
Reverse voltage gain = hrc = VBC / VCE (IB = constant)
2. Output Characteristics: To obtain output resistance find IC and VCB at a
constant IB.
Output admittance 1/hoc = Ro = IE / VCE (IB is constant)
Forward current gain = hfc = IE / IB (VCE = constant)
Procedure:
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 78
Input Characteristics:
1. Connect the circuit as shown in the circuit diagram.
2. Keep output voltage VCE = 2V by varying VCC.
3. Varying VBB gradually, note down base current IB and base-emitter voltage VBC.
4. Initially vary VBB in steps of 0.1V. Once the current starts increasing vary VBB in
steps of 1V up to 12V.
5. Repeat above procedure (step 3) for VCE = 4V
Output Characteristics:
1. Connect the circuit as shown in the circuit diagram.
2. Keep emitter current IB = 20 A by varying VBB.
3. Varying VCC gradually in steps of 1V up to 12V and note down collector
current IE and Collector-Emitter Voltage(VCE).
4. Repeat above procedure (step 3) for IB =0µA, 40µA, 60µA.
Result:
The h-parameters for a transistor in CC configuration are:
a. The Input Resistance (hic) _______________Ohms.
b. The Reverse Voltage Gain (hrec) _______________.
c. The Output Conductance (hoc) _______________ Mhos.
d. The Forward Current Gain (hfc) _______________.
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 79
Additional Experiments
Circuit Diagram :
A. Series Clippers :
1. To pass positive peak above V level
Vi
V Vm
2 t
Vo
2 t
2. To pass positive peak above some reference level ( VR +V )
Vi
VR+V
Vm
2 t
Vo
2 t
Vi
Vo
V
Vi
Vo
VR +V
10 V p-p
500 Hz
10 V p-p
500 Hz
A K
A K
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 80
Testing of diode clipping and Clamping circuits
Aim : To design and study the series and shunt clipping circuits using diodes.
Apparatus Required :
Sl.
No. Particulars Range Quantity
1. Diode ( 1N4007 / BY 127 ) - 02
2. Resistor As per design -
3. Multimeter - 01
4. CRO Probes - 3 set
5. Spring Board and Connecting wires - -
Theory:
A clipper is a circuit that removes either positive or negative portion of a waveform.
This kind of processing is useful for signal shaping, circuit protection and communications.
The clippers are usually constructed by using diodes and resistors and some times to adjust
the clipping level DC power supplies are also used. There are two types of clippers namely
series clippers and shunt clippers. If the clipping element (diode) is in series with the source
then we call it as series clippers and if the clipping device is in parallel with the source then
we call such circuit as shunt clippers. Further based on the portion of a waveform clipped the
clippers can be classified as positive clippers, negative clippers and two level clippers
(combination clippers).
Procedure:
1. Components / Equipment are tested for their good working condition.
2. Connections are made as shown in the circuit diagram
3. Apply a sine wave of amplitude greater than the designed clipping level with
frequency 500 Hz.
4. Observe the output wave form on the CRO
5. Observe the transfer characteristic curve on CRO by applying input waveform to
channel – X and output waveform to channel – Y.
6. Measure the clipped voltage and compare with the designed value.
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 81
3. To pass negative peak above -V level
Vi
Vm
-V 2 t
Vo
2 t
4. To pass negative peak above some reference level (-VR - V )
Vi
Vm
Vo 2 t
-VR-V
2 t
Vi
Vo
- V
Vi
Vo
- VR - V
10 V p-p
500 Hz
10 V p-p
500 Hz
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 82
5. To pass positive peak above some reference level (VR1+V) and negative peak above
some reference level -VR2 - V
Vi
VR1+V Vm
2 t
-VR2-V
Vo
2 t
Result:
A. Series Clippers
Sl.
No. Circuit
Designed
Clipping level
(Theoretical)
Observed
Clipping level in
CRO(Practical)
1. To pass positive peak above V level V = 0.7V
2. To pass positive peak above some
reference level VR +V
VR +V= 2.5+0.7
=3.2V
3. To pass negative peak above -V level -V = -0.7V
4. To pass negative peak above some
reference level -VR - V
-VR -V = -3-0.7
= -3.7V
5.
To pass positive peak above some
reference level (VR1+V) and negative
peak above some reference level -VR2-V
VR1+V = 2+0.7=2.7V
-VR2 - V =-2-0.7
=-2.7V
Vi
Vo
-VR2- V
VR1+ V
10 V p-p
500 Hz
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 83
B. Shunt Clippers
6. To remove positive peak above V level
Vi
V Vm
2 t
Vo
V
2 t
7. To remove positive peak above some reference level (VR +V)
Vi
VR+V Vm
2 t
Vo
VR+V
2 t
Vi
Vo
V
Vi
Vo
VR+ V
10 V p-p
500 Hz
10 V p-p
500 Hz
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 84
-V
VR- V
8. To remove negative peak above -V level
Vi
Vm
-V 2 t
Vo
-V 2 t
9. To pass positive peak above some reference level (VR-V)
Vi
VR-V Vm
2 t
Vo
VR-V 2 t
Vi
Vo
Vi
Vo
10 V p-p
500 Hz
10 V p-p
500 Hz
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 85
VR1+V
-VR2-V
10. To remove positive peak above some reference level (VR1+V) and negative peak above
some reference level (-VR2-V)
Vi
VR1+V Vm
2 t
-VR2-V
Vo
VR1+V
t 2 -VR2-V
Design :
Example – 1 : Design a clipping circuit to pass the positive peak above the reference
level 2V (Circuit 2)
VR + V = 2V Assume the diode to be silicon make then V = 0.6 V
Then VR = 2 – 0.6 = 1.4 V
Assume Rr = 100 K and Rf = 10
Then R = Rr Rf = 1 K
Example – 2 : Design a clipping circuit to remove positive peak above + 3 V negative
peak above – 4 V (Circuit 12)
VR1+V = + 3 V Assume the diode to be silicon make then V = 0.6 V
VR1 = 3 – 0.6 = 2.4 V
-VR2-V = - 4 V
-VR2 = - 4 + 0.6 = - 3.4 V
Vi
Vo
Vo
10 V p-p
500 Hz
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 86
VR2 = 3.4 V
Assume Rr = 100 K and Rf = 10
Then R = Rr Rf = 1 K
Result:
B. Shunt Clippers
Sl.
No. Circuit
Designed
Clipping level
(Theoretical)
Observed
Clipping level in
CRO(Practical)
6. To remove positive peak above V level V = 0.7V
7. To remove positive peak above some
reference level (VR +V)
(VR +V)=2+0.7=2.7V
8. To remove negative peak above -V level -V =-0.7V
9. To pass positive peak above some
reference level (VR-V)
VR-V =3-0.7=2.3V
10.
To remove positive peak above some
reference level (VR1+V) and negative
peak above some reference level (-VR2-V)
VR1+V =2+.7=2.7V
-VR2-V =-3-0.7
=-3.7V
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 87
Vi
Vo t
V
t
V
Vi
Vo t
V
t
V
Vi
Vo t
V
V
-V
VR-V
Circuit Diagram:
Positive Clampers:
1. Negative peak clamped to -V level
2. Negative peak clamped to positive reference level (VR-V)
3. Negative peak clamped to negative reference level (-VR-V)
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 88
A1. Clamping Circuits
Aim : To design a clamping circuit for the given specification.
Apparatus Required :
Sl.
No. Particulars Range Quantity
1. Diode ( 1N4007 / BY 127 ) - 01
2. Resistors & Capacitors As per design -
3. CRO Probes - 3 set
4. Spring board and connecting wires
Theory :
Clamper is a circuit which adds DC level to an AC waveform. There are two types of
clampers namely positive clampers and negative clampers. In positive clampers positive DC
level will be added to the AC waveform or the negative peak will be clamped to some other
level. In Negative peak clampers negative DC level will be added to the AC waveform or the
positive peak will be clamped to some other level.
Clampers are very much used in communication systems for example clampers are
used in analog television receivers for the purpose of restoring the dc component of the video
signal prior to its being fed to the picture tube.
Procedure :
1. Components / Equipment are tested for their good working condition.
2. Connections are made as shown in the circuit diagram
3. Apply a square wave / triangular wave / sine wave input of amplitude 10 V peak to
peak and frequency of 1 kHz
4. Observe the input and output waveform keeping CRO in DC position
5. Measure the clamping level and compare with the designed value
Design :
For a clamper RC T let RC = 10 T
Assume f = 1 KHz, hence T = 1 ms, choose C = 1 f
Then R = 10 K
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 89
Vi
Vo t
t
V
V
Vi
Vo t
V
t
V
Vi
Vo t
V
t
V
V
VR+V
-VR+V
Negative Clampers :
4. Positive peak clamped to V level
5. Positive peak clamped to positive reference level (VR+V)
6. Positive peak clamped to negative reference level (-VR+V)
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 90
Result:
A. Positive Clampers
Sl.
No. Circuit
Designed
Clipping level
(Theoretical)
Observed
Clipping level in
CRO(Practical)
1. Negative peak clamped to -V level - V =-0.7V
2.
Negative peak clamped to positive
reference level (VR-V)
VR-V =2-0.7
=1.3V
3.
Negative peak clamped to negative
reference level (-VR-V)
-VR-V =-3-0.7
=-3.7V
B. Negative Clampers
4. Positive peak clamped to V level V =0.7V
5.
Positive peak clamped to positive
reference level (VR+V)
VR+V = 4+0.7
=4.7V
6.
Positive peak clamped to negative
reference level (-VR+V)
-VR+V =
-3+0.7=-2.3V
Example – 1 :Design a clamping circuit to clamp the negative peak to +3V ( Circuit 2 )
VR - V = 3 V Let the diode be silicon make then V = 0.6 V
VR = 3 + 0.6 = 3.6 V
2.Negative peak clamped to negative reference level (-2V)
-VR-V= -2,
VR=1.4V
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 91
Circuit Diagram :
Vo
t
Cross over distortion
Tabular Column:
Vi = ____________ V : VCC = ________ V
Sl.
No. RL in Ic in mA Vo in Volt Pdc = VCC. IC Pac=Vo2 / 8RL % =Pac / PDC
B E
C
C
2N3055 / OC26
0.1 F 1000 F
TR1
TR2
OC26
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 92
A2. Class B Push Pull Power Amplifier
Aim: To determine the efficiency of class B push pull amplifier and to find the optimum
load.
Apparatus Required:
Sl.
No. Particulars Range Quantity
1. Transistor AD149 and 2N3055 - 1 each
2. Resistors as per design - -
3. Mili ammeter 0-20 mA 01
4. Multimeter - 01
5. CRO Probes - 3 Set
6. Spring Board and Connecting wires - -
Theory:
To improve the full power efficiency of the Class A type amplifier it is possible to
design the amplifier circuit with two transistors in its output stage producing a "push-pull"
type amplifier configuration. Push-pull operation uses two "complementary" transistors, one
an NPN-type and the other a PNP-type with both power transistors receiving the same input
signal together that is equal in magnitude, but in opposite phase to each other. This results in
one transistor only amplifying one half or 1800 of the input waveform while the other
transistor amplifies the other half or remaining 1800 of the waveform with the resulting "two-
halves" being put back together at the output terminal. This pushing and pulling of the
alternating half cycles by the transistors gives this type of circuit its name but they are more
commonly known as Class B Amplifiers
The transistor base inputs are in "anti-phase" to each other as shown in circuit
diagram, thus if TR1 base goes positive driving the transistor into heavy conduction, its
collector current will increase but at the same time the base current of TR2 will go negative
further into cut-off and the collector current of this transistor decreases by an equal amount
and vice versa. Hence negative halves are amplified by one transistor and positive halves by
the other transistor giving this push-pull effect. Unlike the DC condition, these AC currents
are ADDITIVE resulting in the two output half-cycles being combined to reform the sine-
wave which then appears across the load. Class B Amplifiers have the advantage over Class
A amplifier so that no current flows through the transistors when they are in their quiescent
state (ie, with no input signal), therefore no power is dissipated in the output transistors when
there is no signal present
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 93
Unlike Class A amplifier stages that require significant base bias thereby dissipating lots of
heat - even with no input signal. So the overall conversion efficiency ( η ) of the amplifier is
greater than that of the equivalent Class A with efficiencies reaching as high as 75% possible
resulting in nearly all modern types of push-pull amplifiers operated in this Class B mode.
While Class B amplifiers have a much high gain than the Class A types, one of the
main disadvantages of class B type push-pull amplifiers is that they suffer from an effect
known commonly as Crossover Distortion. This occurs during the transition when the
transistors are switching over from one to the other as each transistor does not stop or start
conducting exactly at the zero crossover point even if they are specially matched pairs. This
is because the output transistors require a base-emitter voltage greater than 0.7v for the
bipolar transistor to start conducting which results in both transistors being "OFF" at the same
time. One way to eliminate this crossover distortion effect would be to bias both the
transistors at a point slightly above their cut-off point. This then would give us what is
commonly called an Class AB Amplifier circuit.
Ideal Graph:
%
RL in
max
Optimum load
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 94
Procedure :
1. Connections are made as shown in circuit diagram
2. Keep RL = 1K, and adjust the amplitude of input signal for distortion less output
waveform.
3. RL is varied in convenient steps and corresponding Vo and IC are recorded.
4. Calculate PDC and Pac and calculate efficiency
5. Plot a graph of % versus RL and obtain the optimum load.
Result :
Maximum efficiency = ___________ %, Optimum load, RL opt = __________
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 95
Circuit Diagram :
Design :
Given, VCE = 5 V and IC = 2 mA
Assume = 100
VCC = 2VCE = 2 X 5 = 10 V
Let VRE = 10% VCC = 1 V
RE = VRE / ( IC + IB )
IB = IC / = 2mA / 100 = 20 A
RE = 1 / ( 2m + 20 ) = 495, Choose
RE = 470
Apply KVL to collector loop
VCC – IC RC – VCE – VE = 0
RC = ( VCC – VCE – VE ) / IC = ( 10
– 5 – 1 ) / 2 m
RC = 2 K Choose RC = 1.8 K
Let IR1 = 10 IB = 10 X 20 A = 200
A
VR2 = VBE + VE = 0.6 + 1 = 1.6 V
( Since transistor is silicon make
VBE = 0.6 V )
R2 = VR1 / ( IR1 – IB ) = 1.6 / ( 200 A
- 20 A ) = 8.8 K Choose R2 = 8.2
K
R1 = ( VCC – VR2 ) / IR1 = ( 10 – 1.6 ) /
200 A = 42 K Choose R1 = 47
K
XCE < < RE, XCE = RE / 10
1 / ( 2 f CE ) = 470 / 10 Let f = 100 Hz
CE = 33 F Choose CE = 47 F
Choose CC1 = CC2 = 0.1 F
Vo
t
T
fo = 1 / T Hz
C
B
E
SL100
or
CL100
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 96
A3. Crystal Oscillator
Aim : To design and test a crystal oscillator.
Apparatus Required :
Sl.
No. Particulars Range Quantity
1. Transistor SL 100, Crystal - 1 each
2. Resistors & Capacitors As per design -
3. CRO Probes - 3 Set
4. Multi meter - 01
5. DCB - 02
6. Spring board and connecting wires - -
Theory :
An oscillator is an electronic circuit that produces a repetitive electronic signal, often
a sine wave or a square wave. A crystal oscillator is an electronic circuit that uses the
mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical
signal with a very precise frequency. This frequency is commonly used to keep track of time
(as in quartz wristwatches), to provide a stable clock signal for digital integrated circuits, and
to stabilize frequencies for radio transmitters and receivers. The most common type of
piezoelectric resonator used is the quartz crystal, so oscillator circuits designed around them
were called "crystal oscillators".
Procedure :
1. Components / equipment are tested for their good working condition.
2. Connections are made as shown in the diagram
3. The quiescent point of the amplifier is verified for the designed value.
4. Observe the output wave form on CRO and measure the frequency.
5. Verify the frequency with the crystal frequency.
Result:
Q Point: VCE = _____ V, Ic = ______ mA
fo Crystal = _____________ Hz
fo Practical = _______________ Hz
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 97
REFERENCES
1. “Functional Electronics” by K. V. Ramanan, Tata McGraw Hill Publications.
2. “Electronic Devices and Circuits” by David A. Bell, PHI India Publications, New
Delhi 4th edition 2004.
3. “Electronic Devices and Circuit Theory” by Robert L. Boylestad and Louis
Nashelsky, PHI India Publications, New Delhi 8th edition 2009.
4. “Integrated Electronics” by Jacob Millman and Christos C. Halkias, Tata McGraw
Hill Publications, 1991 edition.
5. “Network Analysis” by M. E. Van Valkenburg, PHI India Publications, 3rd Edition,
1974.
6. “Network Analysis” by G. K. Mithal, Kanna Publication, 14th Edition.
7. “Modern Physics” by Kenneth S. Krane, John Wiley and Sons Publications, 2nd
Edition 1998.
8. “Digital Logic Applications and Design”, John Yarbrough, Thomson Learning, 2001.
9. “Digital Principles and Design “, Donald D Givone, Tata McGraw Hill Edition,
2002.
10. “Fundamentals of logic design”, Charles H Roth, Jr; Thomson Learning, 2004.
11. “Logic and computer design Fundamentals”, Mono and Kim, Pearson, Second
edition, 2001.
12. “Logic Design”, Sudhakar Samuel, Pearson/Saguine, 2007.
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 98
Viva Questions
1. Define rectifier.
2. Compare different type of rectifiers.
3. What are the different types of filters.
4. What are conductors, insulators, and semi-conductors? Give examples.
5. .Define gain of the amplifier
6. What are the functions of the three resistances R1 , R2 , Re?
7. .What are the functions of the capacitances CE and CC ?
8. Which configuration of a transistor is preferred when a transistor is used as a switch and
why?
9. What is quiescent point?
10. .What is load line?
11. Compare FET with BJT.
12. 1.Explain the function of the tank circuit.
13. What is Barkhausen’s criterion and how is it satisfied?
14. .How can the frequency of oscillations be altered
15. What are Analog Systems? Give Examples
16. What are Digital Systems? Give Examples
17. State Demorgans Law?
18. Define MINTERM, MAX TERM
19. Which are the basic gates, universal gates
20. Define combinational network with example
21. Define Sequential Network with example
22. Explain the significance of a Don’t care function
23. What is a minimal Sum, Minimal product?
24. Define Comparator
25. Define Decoder
26. Define Encoder
27. Define setting and clearing in terms of flip-flop
28. Explain SR Latch
29. Give an application of SR Latch
30. Explain Timing Diagram
31. Explain Propagation Delay in gates
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 99
MODEL QUESTIONS
1. a) Design a RC coupled single stage BJT amplifier and determine the Gain-frequency
response, input and output impedances.
b) Realize and verify the truth table of a full adder and half adder using basic gates
and NAND gates only
2. a) Design a RC coupled single stage FET amplifier and determine the Gain-frequency
response, input and output impedances.
b) Realize and verify the truth table of full and half subtractor using basic gates and
NAND gates only
3. a) Design the clipping circuit, which has the following transfer characteristics.
b) Conduct a suitable experiment on 7483 IC to realize the following
Operation on the given 4 bit data i) Addition ii) 2’s Complement Subtraction
4. a) Design and test the performance of BJT-RC phase shift oscillator for fo = 1kHz.
b) Simplify and realize the given Boolean Expression using Basic Logic
gates/universal gates and verify the truth table
5. a) Rig up and test Center tap full wave rectifier circuit with and without ‘C’ filter and
determine ripple factor, efficiency and regulation.
b) Realize a 3-bit binary asynchronous up counter/down counter using IC 7476
(N<=7) and verify its truth table
6. a) Design the clipping circuits to obtain the following output waveform.
b) Realize using XOR/ NAND gates and verify the truth table of
(i) Binary to gray converter (ii) Gray to Binary Converter
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 100
7. a) Design and test the performance of a BJT Crystal oscillator.
b) Conduct an experiment to convert the given BCD data to excess-3 code/excess-3 to
BCD Using minimum number of basic gates
8. a) Design and test clamping circuits to clamp positive peak\ negative peak to
________ reference level
b) Design and realize a Ring counter/Johnson counter.
9. a) Design and test clipping (series) circuits to pass positive peak above ___________
Reference level
b) Design and realize a sequence generator for the sequence……………………….
10. a) Rig up and test Bridge rectifier circuit with and without ‘C’ filter and determine
ripple factor, efficiency and regulation
b) Realize a Mod N binary synchronous counter using 7476 and verify the truth table
11. a) Rig up and test a class B push pull amplifier and determine its conversion
efficiency.
b) Realize and verify the truth table of full and half subtractor using basic gates and
NAND gates only
12. a) Design and test clipping (shunt) circuit to remove positive peak above ________
Reference level
b) Realize a Modulo N counter using 74192/ 74193 with a given preset value and
verify its truth table.
13.Design a BJT Darlington Emitter follower with and without bootstrapping and
determine the gain, input and output impedances.
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 101
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 102
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 103
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 104
[Electronics Lab : 15 EEL 38] 2016-17
Dept. of EEE, CIT, Gubbi, Tumkur – 572 216 105
fo = 1 / T
Hz T t Vo E
SL100
or
CL100
B C