1
With accurate
readings
XII
Electronics
(C-2)
Practical Experiments Paper-I
Prof. Dattaraj Vidyasagar
www.vsagar.org
Vidyasagar Academy, Practical Booklet of XII Bifocal Electronics, www.vsagar.org
2
N O T ES S P AC E
Vidyasagar Academy, Practical Booklet of XII Bifocal Electronics, www.vsagar.org
3
Experiment 1 (Set-1)
Name –Line regulation using zener diode.
Aim – to study the working of zener regulator and its line regulation.
Apparatus –resistors, capacitor, transformer, zener diode, rectifier diodes, dimmer stat, voltmeter
(0–10V),connecting wires, etc.
Connection diagram –
g
r
o
.
r
a
g
Circuit diagram of zener line regulator
Observation table –
Sr.
No.
Line voltage
(Vin)
DC Output voltage
(Vo)
170V
180V
190V
200V
210V
220V
230V
240V
250V
260V
270V
4.8V
a
s
v
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
5.0V
5.1V
5.2V
5.4V
5.6V
5.6V
5.6V
5.6V
5.6V
5.6V
Formula –
SR  Vo1  Vo 2
also,
SR
% SR 
 100
Vo1
Vo1> Vo2, Take any
Vidyasagar Academy, Practical Booklet of XII Bifocal Electronics, www.vsagar.org
two consecutive
values of Vo
4
Specifications of components –
Type of component
Resistor
LED
Diodes
Zener diode
Capacitor
Transformer
Dimmerstat
Specifications
47, ½W, carbon composition, 5% tolerance
Color: RED , VF = 1.65V
1N4001 rectifier diode
5.6V, 400mW zener diode
1000F/25V electrolytic capacitor
6V–0V–6V, 500mA secondary transformer
170V to 270V variable dimmerstat
Procedure –
1)
2)
3)
4)
5)
6)
Be careful while doing the experiment, as it carries dangerously high voltage.
Switch on the circuit and keep its line voltage at 170VAC, using dimmerstat.
Measure the DC output voltage of the circuit in this position of dimmerstat.
Repeat the above procedure as per given in observation table.
Plot a graph of line voltage versus output DC voltage.
Calculate percentage line regulation using the given formula.
o
.
r
g
r
Results –
a
g
1) At minimum line voltage, the output voltage Vo = 4.8V.
2) At maximum line voltage, the output voltage Vo = 5.6V.
a
s
v
Vidyasagar Academy, Practical Booklet of XII Bifocal Electronics, www.vsagar.org
5
Experiment 2 (Set-1)
Name – Load regulation using zener diode.
Aim – to study the working of zener regulator and its load regulation.
Apparatus – resistors, capacitor, transformer, zener diode, rectifier diodes, voltmeter (0–10V),
ammeter (0–100mA), connecting wires, etc.
Connection diagram –
g
r
o
.
r
Circuit diagram of zener load regulator
a
g
Observation table –
Sr.
No.
Load current
Output voltage
(IL)
(Vo)
a
s
1.
v
2.
3.
4.
5.
6.
7.
8.
9.
0 (min.)
VNL= 5.6V
10mA
5.6V
15mA
5.6V
20mA
5.6V
25mA
5.6V
30mA
5.6V
35mA
5.2V
40mA
5.0V
50mA
4.8V
10. Max. 50mA
VFL= 4.8V
Formula –
V  VFL
% LR  NL
 100
V NL
Where,
VNL  Load voltage with no load current
VFL  Load voltage with full load current
Vidyasagar Academy, Practical Booklet of XII Bifocal Electronics, www.vsagar.org
6
Specifications of components –
Type of component
Resistor
Potentiometer
LED
Diodes
Zener diode
Capacitor
Transformer
Voltmeter
Ammeter
Specifications
47, ¼W, carbon composition, 5% tolerance
1k/5W wire wound pot
color RED , VF = 1.65V
1N4001 rectifier diode
5.6V, 400mW zener diode
1000F/25V electrolytic capacitor
6V–0V–6V, 500mA secondary transformer
0–10V, DC voltmeter
0–100mA, DC ammeter
Procedure –
1) Switch on the circuit and keep load resistance (RL) in maximum resistance position.
2) Measure the output voltage of the circuit in this condition.
g
r
3) Note it down as VNL = 5.6V in observation table.
4) Now reduce the resistance of load by varying the pot in equal steps, note down
corresponding readings of output voltage and load current.
o
.
r
5) Reduce RL for maximum load current. Note down VFL = 4.8V in observation table.
6) Plot a graph of output DC voltage versus load current.
7) Calculate percentage load regulation using given formula.
Results –
a
g
1) At maximum load resistance, the output voltage Vo = 5.6V and IL = 10mA.
2) At minimum load resistance, the output voltage Vo = 4.8V and IL = 50mA.
a
s
v
Vidyasagar Academy, Practical Booklet of XII Bifocal Electronics, www.vsagar.org
7
Experiment 3 (Set-1)
Name –study of line regulation using IC LM 317.
Aim –to calculate values of R1 and R2 and study line regulation of the circuit.
Apparatus – resistors, capacitor, transformer, IC LM 317, rectifier diodes, dimmerstat, voltmeter
(0–10V), connecting wires, etc.
Connection diagram –
o
.
r
Circuit diagram of LM 317 voltage regulator for line regulation
a
g
Observation table –
Sr.
No.
Line voltage
(Vin)
DC Output voltage
(Vo)
1.
170V
4.6V
4.7V
4.8V
4.9V
5.0V
5.0V
5.0V
5.0V
5.0V
5.0V
5.0V
a
s
2.
3.
4.
v
5.
g
r
180V
190V
200V
210V
6.
220V
7.
230V
8.
240V
9.
250V
10.
260V
11.
270V
Procedure –
1) First, calculate R2 using the formula, for given value of Vo = 5V. Consider R1 = 100.
R

Vo  1.25 2  1
 R1

2) Solder calculated value of R2 in the circuit. For non–standard value of R2 use
series/parallel combination of standard resistors.
3) Measure output voltage for various values of line voltage as given in observation table.
4) Plot a graph of line voltage versus output voltage. For this, adjust dimmerstat in circuit.
5) Calculate percentage line regulation using the given formula.
Vidyasagar Academy, Practical Booklet of XII Bifocal Electronics, www.vsagar.org
8
Formula –
SR  Vo1  Vo 2
Vo1> Vo2, Take any
also,
% SR 
two consecutive
values of Vo
SR
 100
Vo1
Specifications of components –
Type of component
IC LM 317
Resistors
LED
Diodes
Capacitor
Transformer
Dimmerstat
Specifications
Adjustable 3–terminal +ve voltage regulator IC,
Vomin = 1.2V, Vomax = 37V, ILmax = 1.5A
SR = 0.01%, LR = 0.1% (typical values),
RR = 80dB, internal short circuit protection.
R1 = 100,
R2 = 300, all ¼W, carbon composition, 5% tolerance
Color: RED , VF = 1.65V
1N4001 rectifier diode
1000F/25V electrolytic capacitor
6V–0V–6V, 500mA secondary transformer
170V to 270V variable dimmerstat
g
r
o
.
r
Pin configurations –
a
g
a
s
v
Pin configurations of IC LM317 and rectifier diode
Note: Do not change given value of R1 = 100. This value ensures minimum load current
requirement (which is 10mA) of the IC which is ILmin = 12.5mA at Vomin = 1.25V.
Results –
1) Calculated value of R2 = 300 for given Vo = 5V.
2) The %SR of IC LM 317 = 8.7%.
Vidyasagar Academy, Practical Booklet of XII Bifocal Electronics, www.vsagar.org
9
Experiment 4 (Set-1)
Name – study of load regulation using IC LM 317.
Aim – to calculate values of R1 and R2 and study load regulation of the circuit.
Apparatus – resistors, capacitor, transformer, IC LM 317, rectifier diodes, voltmeter (0–10V),
ammeter (0–100mA), connecting wires, etc.
Connection diagram –
g
r
o
.
r
a
g
Circuit diagram of LM 317 voltage regulator for load regulation
Observation table –
Sr.
No.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Load current
(IL)
0 (min.)
5mA
10mA
15mA
20mA
25mA
30mA
40mA
60mA
Max. 100mA
a
s
v
Output voltage
(Vo)
VNL = 5V
5.0V
5.0V
5.0V
5.0V
5.0V
5.0V
4.8V
4.6V
VFL = 4.5V
Procedure –
1) First, calculate R2 using the formula, for given value of Vo = 5V. Consider R1 = 100.
R

Vo  1.25 2  1
 R1

2) Solder calculated value of R2 in the circuit. For non–standard value of R2 use
series/parallel combination of standard resistors.
3) Measure Vo and IL for various values of load resistance (RL). Adjust pot to change RL.
4) Plot a graph of output voltage versus load current. For this, adjust the dimmerstat in the
circuit.
5) Calculate percentage load regulation using the given formula.
Vidyasagar Academy, Practical Booklet of XII Bifocal Electronics, www.vsagar.org
10
Formula –
V  VFL
% LR  NL
 100
V NL
Where,
VNL  Load voltage with no load current
VFL  Load voltage with full load current
Specifications of components –
Type of component
IC LM 317
Resistors
LED
Diodes
Capacitor
Transformer
Specifications
Adjustable 3–terminal +ve voltage regulator IC,
Vomin = 1.2V, Vomax = 37V, ILmax = 1.5A
SR = 0.01%, LR = 0.1% (typical values),
RR = 80dB, internal short circuit protection.
R1 = 100,
R2 = 300, all ¼W, carbon composition, 5% tolerance
Color: RED , VF = 1.65V
1N4001 rectifier diode
1000F/25V electrolytic capacitor
6V–0V–6V, 500mA secondary transformer
g
r
o
.
r
Pin configurations –
a
g
a
s
Pin configurations of IC LM317 and rectifier diode
Note – do NOT change given value of R1 = 100. This value ensures minimum load current
v
requirement (which is 10mA) of the IC which is ILmin = 12.5mA at Vomin = 1.25V.
Results –
1) Calculated value of R2 = 300 for given Vo = 5V
2) The percentage LR of IC LM 317 = 10%
Vidyasagar Academy, Practical Booklet of XII Bifocal Electronics, www.vsagar.org
11
Experiment 5 (Set-1)
Name –study of photo relay.
Aim – to assemble the circuit and measure voltages at different points.
Apparatus – resistors, capacitor, transformer, rectifier diodes, DMM, relay, transistors, LDR,
connecting wires, etc.
Circuit diagram –
g
r
o
.
r
Circuit diagram of photo relay
a
g
Observation table –
Supply
Voltage
a
s
Vcc = 6V
Transistor (T1)
Voltage
Vbe = 0.62V
Vce = 0.2V
Transistor (T2)
Voltage
Vbe = 5.8V
Vce = 0.3V
v
Procedure –
1) Solder the circuit on the given tag board, with hot soldering iron.
2) Connect power supply to the circuit and test it under different light conditions.
3) Check that when light falls on LDR, the relay activates and LED glows. When LDR is dark,
the relay deactivates and the LED goes off.
4) For proper sensitivity of LDR, adjust the sensitivity pot in the circuit.
5) Measure voltage at base and collector of transistors in on and off conditions of relay.
6) From above voltages of transistor voltages, determine the operating region of the
transistor.
7) Switch off the circuit and disconnect the LDR from the circuit.
8) Measure the light and dark resistance of the LDR using DMM.
9) Note down the values of LDR, dark resistance = 1M and light resistance = 22.
10) Disconnect the relay coil from the circuit. Measure its resistance using DMM. Note it down
as relay resistance = 300.
Vidyasagar Academy, Practical Booklet of XII Bifocal Electronics, www.vsagar.org
12
Specifications of components –
Type of the component
Diodes
Transistors
Transistor 148/ 548
SK 100
Capacitor
Resistors
Relay
Potentiometer
Transformer
Specifications
1N4001, silicon rectifier diode
Small signal amplifier, silicon transistor, (Gain=100)
Medium power silicon transistor, (Gain = 50)
1000F/25V electrolytic capacitor
1k series resistor, carbon type
Dark resistance 1M, light resistance 22.
6V, 300, single changeover type relay coil
470k, carbon composition type
230V/6V, 500mA step down type
Pin configurations
g
r
o
.
r
a
g
Results –
1) The dark resistance = 1M and light resistance = 22
2) The relay coil resistance = 300
3) In ‘ON’ condition of the circuit, T1 is in ON condition and T2 is in ON conditions.
a
s
v
Vidyasagar Academy, Practical Booklet of XII Bifocal Electronics, www.vsagar.org
13
Experiment 6 (Set-1)
Name – study of inverting amplifier using opamp.
Aim – to study the working of inverting amplifier using IC 741 as voltage amplifier.
Apparatus – resistors, capacitor, transformer (center tapped), rectifier diodes, IC 741,
potentiometer, connecting wires, etc.
Circuit diagram –
o
.
r
Circuit diagram of opamp as inverting DC amplifier
a
g
Observation table –
Sr.
Nos.
R1
v
3
Vo
(Volts)
1.2V
2.0V
0.5V
1.5V
0.8V
1.6V
-1.2V
-2.1V
-1.0V
-3.2V
-2.7V
-5.5V
a
s
1
2
RF
Vin
(Volts)
10k
10k
5k
10k
3.3k
10k
g
r
Measured Calculated
gain
gain
(Vo/Vin)
(RF/R1)
1
1.05
2
2.13
3
3.44
1
1
2
2
3.33
3.33
Gain
difference
0
0.05
0
0.13
0
0.11
Take two readings with different input voltages for each value of R1
Procedure –
1) First solder R1 = 10k and RF = 10k. Now switch on the circuit.
2) Connect DC voltmeter at the output of the circuit. Adjust VR1 to change input voltage
between 0–2V, for taking two different values of input voltage.
3) Measure input/output voltage in each case. Note down the values in observation table.
4) Repeat step 1 to step 3 for different values of R1 i.e. replace R1 with new value by
soldering new resistor. While soldering, every time switch off the circuit.
5) Obtain calculated and observed gain of circuit in each combination of R1 and RF.
6) Compare calculated and measured gain and obtain the difference.
Vidyasagar Academy, Practical Booklet of XII Bifocal Electronics, www.vsagar.org
14
Formulas –
1) The output voltage of inverting amplifier is given by –
Vo 
Rf
 V1 
R1
2) The theoretical gain of the circuit is given by –
Rf
 gain
R1
3) The observed gain of the circuit is given by –
 Vo
 gain
Vi
Specifications of components –
Type of the component
Diodes
IC 741
Capacitor
Resistors
Potentiometer
Transformer
Specifications
1N4001, silicon rectifier diode
Operational amplifier, Supply voltage = 18Vmax,
Input offset voltage = 2mV, input bias current = 80nA,
CMRR = 90dB, input impedance = 2M
Output impedance = 75, slew rate = 0.5V/sec.
1000F/25V electrolytic capacitor
10k, 5k, 3.3k, carbon type 5% tolerance
10k, carbon composition type
230V/6–0–6V, 500mA step down, center tapped
o
.
r
a
g
Pin configurations –
g
r
a
s
v
Result – write down the result for any one reading.
1) The theoretical gain = 3.33 and observed gain = 3.44
2) Gain difference = 0.11
Vidyasagar Academy, Practical Booklet of XII Bifocal Electronics, www.vsagar.org
15
Experiment 7 (Set-1)
Name – study of non-inverting amplifier using opamp.
Aim – to study the working of non-inverting amplifier using IC 741 as DC voltage amplifier.
Apparatus – resistors, capacitor, transformer (center tapped), rectifier diodes, IC 741,
potentiometer, connecting wires, etc.
Circuit diagram –
o
.
r
Circuit diagram of opamp as non-inverting DC amplifier
a
g
Observation table –
Sr.
Nos.
R1
v
3
Vo
(Volts)
1.2V
2.0V
0.5V
0.8V
0.3V
0.6V
2.4V
4.2V
1.2V
2.5V
1.2V
2.5V
a
s
1
2
RF
Vin
(Volts)
10k
10k
5k
10k
3.3k
10k
g
r
Measured Calculated
gain
gain
(Vo/Vin)
(RF/R1)
2
2.1
2.4
3.125
4
4.17
2
2
3
3
4.33
4.33
Gain
difference
0
0.1
0.6
0.125
0.33
0.16
Take two readings with different input voltages for each value of R1
Procedure –
1) First solder R1 = 10k and RF = 10k in the circuit. Now switch on the circuit.
2) Connect DC voltmeter at the output of the circuit. Adjust VR1 to change input voltage
between 0–2V, for taking two different values of input voltage.
3) Measure input/output voltage in each case. Note down the values in observation table.
4) Repeat step 1 to step 3 for different values of R1 i.e. replace R1 with new value by
soldering new resistor.
5) Obtain calculated and observed gain of circuit in each combination of R1 and RF.
6) Compare calculated and measured gain and obtain the difference.
Vidyasagar Academy, Practical Booklet of XII Bifocal Electronics, www.vsagar.org
16
Formulas –
1) The output voltage of non-inverting amplifier is given by –
 R 
Vo  1  f V1
 R1 
2) The theoretical gain of the circuit is given by –
 Rf 
1 
 = gain
R1 

3) The observed gain of the circuit is given by –
Vo
 gain
Vi
Specifications of components –
Type of the component
Diodes
IC 741
Capacitor
Resistors
Potentiometer
Transformer
g
r
Specifications
1N4001, silicon rectifier diode
Operational amplifier, Supply voltage = 18Vmax,
Input offset voltage = 2mV, input bias current = 80nA,
CMRR = 90dB, input impedance = 2M
Output impedance = 75, slew rate = 0.5V/sec.
1000F/25V electrolytic capacitor
10k, 5k, 3.3k, carbon type 5% tolerance
10k, carbon composition type
230V/6–0–6V, 500mA step down, center tapped
o
.
r
a
g
Pin configurations –
a
s
v
Result – write down the result for any one reading.
1) The theoretical gain = 4.33 and observed gain = 4.17
2) Gain difference = 0.16
Vidyasagar Academy, Practical Booklet of XII Bifocal Electronics, www.vsagar.org
17
Experiment 8 (Set-1)
Name – study of inverting adder using opamp.
Aim – to study the working of inverting amplifier using IC 741 as adder circuit.
Apparatus – resistors, capacitor, transformer (center tapped), rectifier diodes, IC 741,
potentiometer, connecting wires, etc.
Circuit diagram –
g
r
o
.
r
Circuit diagram of opamp as inverting adder
a
g
Observation tables –
Sr.
Nos.
Input voltages
v
Calculated
output voltage
(Vo)
-3V
-0.3V
0V
1V
-5.2V
-5V
V1
V2
2V
1V
3V
1V
-0.5V
-1.2V
-0.8V
+2.2V
+2.5V
0.2V
0.3V
0.5V
-1.2V
-1.0V
-0.1V
-0.2V
-0.4V
+0.8V
+0.7V
V1
V2
V3
Vo
2V
1V
-3V
0 Volts
a
s
1.
2.
3.
4.
5.
Observed
output voltage
(Vo)
V3
Procedure –
1) Note that circuit’s gain = unity, since RF = R1.
2) Switch on the circuit and adjust all three input voltages V1, V2 and V3 between 0–3V.
Measure the output voltage.
3) Repeat the same procedure for at least five different combinations of V1, V2 and V3 with
negative values.
4) Thus, take three positive input voltage combinations and two negative combinations.
5) Compare observed with calculated output voltages. Tabulate the readings.
6) Now, adjust V1, V2 and V3 such that output will be zero for all non–zero input voltages.
Vidyasagar Academy, Practical Booklet of XII Bifocal Electronics, www.vsagar.org
18
Formula –
The output voltage of inverting adder is given by –
 Vo  V1 V2 V3 

 


Rf
 R1 R 2 R 3 
Let R1= R2 = R3 = RF, then the equation becomes –
Vo = – (V1 + V2 + V3)
Specifications of components –
Type of the component
Diodes
IC 741
Capacitor
Resistors
Potentiometer
Transformer
Specifications
1N4001, silicon rectifier diode
Operational amplifier, Supply voltage = 18Vmax,
Input offset voltage = 2mV, input bias current = 80nA,
CMRR = 90dB, input impedance = 2M
Output impedance = 75, slew rate = 0.5V/sec.
1000F/25V electrolytic capacitor
10k, 5k, 3.3k, carbon type 5% tolerance
10k, carbon composition type
230V/6–0–6V, 500mA step down, center tapped
Pin configurations –
o
.
r
g
r
a
g
a
s
v
Result –
1) The gain of the circuit = 1 (unity)
2) For Vo = 0, the non-zero values of V1 = 2V, V2 = 1V and V3 = -3V
Vidyasagar Academy, Practical Booklet of XII Bifocal Electronics, www.vsagar.org
19
Experiment 9 (Set-1)
Name – study of IC 555 as MMV.
Aim – to study the working IC 555 in Monostable Multivibrator mode as off delay timer.
Apparatus – resistors, capacitors, transformer, rectifier diodes, LED, IC 555, stop watch,
connecting wires, etc.
Circuit diagram –
g
r
o
.
r
Circuit diagram of IC 555 as monostable multivibrator
a
g
Observation table –
Sr.
No.
a
s
1
2
3
v
4
Resistor
Capacitor Time measured Time calculated
Time
Value (R1) Value (C1)
(sec)
(sec)
difference
1.5sec
1.1sec
0.4sec
3sec
2.42sec
0.48sec
10F
5sec
5.17sec
0.17sec
10F
14sec
11.0sec
3.0sec
100k
10F
220k
10F
470k
1M
Procedure –
1) Construct the circuit on given circuit board, by soldering different components and wires.
2) Note the color code values of given resistors.
3) Connect any one value of resistor (R) and capacitor (C), as per given in the observation
table.
4) Switch on the circuit and push the trigger switch (S1) momentarily. Do not push the switch
for a long time.
5) The LED must glow. Measure the time for which the LED glows, using stopwatch.
6) Take five readings for five different values of (R), as shown in observation table.
7) Calculate the time for each of the RC combination.
8) Compare observed time, calculated time and obtain difference between them.
Vidyasagar Academy, Practical Booklet of XII Bifocal Electronics, www.vsagar.org
20
Formula –
The pulse width i.e. the time for which LED remains on is given by –
T = 1.1 x R1 x C1
Where, R1 is in ohms and C1 is in Farad
Specifications of components –
Type of the component
Diodes
IC 555
LED
Capacitors
Resistors
Transformer
Specifications
1N4001, silicon rectifier diode
Timer IC, Supply voltage = 18Vmax
Color: RED, VF = 1.65V
1000F/25V,
10F/63V, electrolytic capacitor
100k, 220k, 330k, 470k 1M,
all carbon type 5% tolerance
230V/6–0–6V, 500mA step down, center tapped
g
r
Pin configurations –
o
.
r
a
g
a
s
Brief theory –
Pin–1: it is connected to ground of power supply.
Pin–2: it is called trigger pin. It triggers i.e. starts up time cycle of IC, when its voltage is less than ⅓ of
supply voltage. Hence, output of IC becomes high.
Pin–3: it is output pin. It gives complementary output condition. Thus, it can source or sink a maximum
current of 200mA into the load resistor.
Pin–4: it is reset pin. When it is +ve, the IC works normally. However when it is –ve, the IC stops its working,
whatever may be the signal at pin–2.
Pin–5: control voltage pin. It is used to change the threshold voltage of the IC. When it is not in use, it is
returned to ground through a small capacitor of 0.01F to avoid noise pickup.
v
Pin–6: it is threshold pin. It finalizes the time cycle of the IC, when its voltage becomes ⅔ of power supply
voltage or control voltage. Hence, output of IC becomes low.
Pin–7: it is discharge pin. It becomes active through internal transistor, when output of IC is low. It
discharges external capacitor into itself.
Pin–8: it is connected to +ve terminal of power supply, generally 3V to 18V.
Result – write down any one value of the reading.
1) The observed value of time T = 14sec
2) The calculated value of time T = 11sec
3) The difference between calculated and observed time = 3sec
Vidyasagar Academy, Practical Booklet of XII Bifocal Electronics, www.vsagar.org