To Construct A Switch Using Transistor

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Investigatory Project
On
To Construct A Switch Using A
Transistor
Guided by:- Mr. Bhupesh Nagoda
Submitted by:- Mitesh Kumar

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Class: 12th
B
Certificate
This is to certify that Mitesh Kumar, student of class 12th
B,
Kendriya Vidyalaya Ahmedabad Cantt has successfully
completed his project titled “To Construct A Switch Using A
Transistor” under the guidance of Mr. Bhupesh Nagoda
during the academic year 2018-2019 in the partial fulfillment
of AISSCE, Delhi.
Signature:-
(Subject Teacher)
Signature:-
(Principal)

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Certificate

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Acknowledgement
In the completion of this project successfully many people
have best owned upon me their blessings and heart pledged
support, this time I am utilizing to thank all the people who
have been considered with this project.
I would also like to thank my principal Smt. A. P. Kachchap
and my physics teacher Mr. Bhupesh Nagoda whose
valuable guidance has been the ones that helped me to
complete this project and make it a success, his suggestions
and his instructions served as a major contribution towards
the of this project.
Then I would like to thank my parents and friends who have
helped me with their valuable suggestions.

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Contents
Introduction
Objective
Apparatus Required
Theory
Procedure
Observations
Conclusion
Result
Bibliography

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Introduction
A transistor is a three terminal electronic component which
is made of semiconductor material. A transistor has three
terminals namely, emitter, base and collector which forms
two junctions BE and CE
Emitter is the region thru which majority carriers enter the
transistor. Emitter is heavily doped. Base is the middle layer
and it is very lightly doped. Collector is wide and moderately
doped.
Transistors are fundamentally current amplifiers. The
transistor is essentially a resistor which allows current to
flow. The word transistor is a contraction of current-
transferring resistor.

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Transistors are commonly used in amplification, switching,
and buffering signals or applied voltages.

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Experiment
Objective:- To Construct A Switch Using A Transistor & To
Draw The Graph Between Input & Output Voltage & To Mark
The Cut-Off, Saturation And Active Region.
Requirements:- pnp transistor (BC 108 or 2TX300), 3V
battery, two high resistance (100KΩ, 10KΩ), 6V battery, bulb
(6V, 0.06V), 0-3 voltmeter, 0-6 voltmeter, two one way keys,
connection wires.
Theory:- In a common emitter circuit of a transistor, emitter
base make input section and is forward baised and emitter
collector junction make output section and is reverse baised.
Appling Kirchhoff’s Law, for
input circuit, VBB= IBRB+VBE
for output circuit, VCE=VCC-ICRC
But VBB=Vi and VCC=Vo,
Then, Vi=IBRB+VBE

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Vo=VCC-ICRC
The variation in the output voltage with respect to the
variation in the input voltage for a Si transistor are shown in
the figure.
Circuit Diagram:-

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Procedure:-
I. Make a circuit diagram.
II. Make all connections tight.
III. Note the least counts and zero errors of voltmeters.
IV. Make the voltmeters readings zero in Vi & Vo.
V. Increase the voltage from input battery VBB from 0 to 0.6V
and read it in voltmeter Vi and record the reading in
voltmeter Vo.
VI. Further increase in the input voltage (0.6<Vi≤1V) and
record the reading in both voltmeters. The reading in
voltmeter Vo, decreases continuously.
VII. With further increase in Vi (Vi>1V) and again record the
reading in both voltmeters. The reading in the output
voltmeter is found to decrease in further towards zero
through it may never be zero.
VIII. Plot the reading of Vi & Vo by taking Vi on X- axis and Vo
on Y-axis.
IX. The graph will be similar to the graph shown above.

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Observations:-
Input Voltage (Vi) Output Voltage (Vo)
0.1V 3.75V
0.2V 3.72V
0.3V 3.70V
0.4V 3.60V
0.5V 2.90V
0.6V 2V
0.7V 1.50V
0.8V 0.62V
0.9V 0.20V
1V 0.12V
1.1V 0.11V
1.2V 0.10V
1.3V 0.09V
1.4V 0.09V
1.5V 0.08V
Conclusion:-
I. When the input voltage Vi (0 to 0.6) then transistor is in
cut-off region. The transistors do not act.
II. When the input voltage Vi (0.6<Vi≤1V) then transistor is
in active region. The transistor acts.

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III. The transistor in cut-off region act as switch in OFF
position and in saturation region. The transistor acts.
IV. The transistor in cut-off region act as switch OFF position
and in saturation region act as switch in ON position.
Result:-

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Bibliography:-
I. https://www.google.com/
II. https://www.wikipedia.org/
III. https://www.learncbse.in/