engineering project

1. IFET COLLEGE OF ENGINEERING
(AN AUTONOMOUS INSTITUTION)
Villupuram
PRESENTED BY
RAKESH SHARMA.M (ECE –B)
RAMACHANDRAN.S (ECE –B)
SABARVANATHAN.S (ECE -B)
SIMPLE TRANSISTOR
TESTER

2. ABSTRACT:
• In electronics most commonly required component is transistor.
• Therefore the testing of the transistor is very important to avoid
the future inconvenience and the loss to the manufacturer.
• Commonly used devices to test the transistor are costly.

3. INTRODUCTION
• Transistor tester is an instrument which is used to test the electrical
behavior of a transistor.
• A circuit tester is used to check whether a transistor which has
previously been performing properly in a circuit is still operational.
• This type of tester indicates to a technician whether the transistor is
dead or still operative.

4. COMPONENTS
• IC 7400
• Resistor - 10 k ohm and 470 Ohm
• Capacitor – 100 μF and 1μF
• LED – Red and Green
• Battery - 9v
• Breadboard
• Wires and Jumper cut Wires.

5. CIRCUIT DIAGRAM:

6. CONSTRUCTION :
• The Circuit is made on the general purpose Breadboard.

7. • Here the first gate (N1) is designed as a simple oscillator with
resistor R1 and capacitor C2.
• The output of gate N1 (pin 3) is fed to gate N2 (pin 4), which, in
turn, is used to drive the green half of bicolor LED1.
• The remaining gates are used as inverters and buffers.
• In various transistors, the pin configurations are different, so it is
necessary to go through the datasheets to identify the pins.

8. CIRCUIT OPERATION :
• The circuit employs the properties of the gates of low power IC 7400.
• It is a NAND IC with four gates that can be designed in various ways.
• If the inserted in the socket is npn type, the current flows from output pin 4
of gate N4 through bicolour LED1 and its green half glows. This is due to
conduction of the TUT.
• If the transistor is pnp type, the current flow is reversed and the red half of
bicolor LED1 glows.

9. • This happens due to the high state of outputs at pins 10 and 11 of
gates N3 and N4, respectively.
• This is because output pin 4 of N2 is at low level.
• Bicolor LED1 used in the circuit is a two-lead version with red and
green LEDs connected in inverse parallel inside a common case.
• The cathode of one LED forms the anode of the other, so
depending on the direction of current flow either red or green LED
lights up.

10. Transistor Green LED Red LED Condition of
the transistor
Npn On Off Good
Pnp Off On Good
Npn/Pnp On On Shorted
Npn/Pnp Off Off Open
Table I
Status of bicolor LED 1 for Different Conditions of the
Transistor

11. TESTING
( For Different Type of Transistors)

12. APPLICATION :
• In our modern society, extensive use of electricity has enabled various
uses of transistors in every electronic circuit.
• Transistors are used in our day to day lives in many forms which we are
aware of as amplifiers and switching apparatus.
• By this transistor tester we can know whether a transistor is in good
condition or not.
• We can also find whether the transistor is NPN or PNP type.

13. CONCLUSION :
• The circuit is simple as compared to other transistor testers, and
therefore, is useful for technicians as well as students.
• It can be easily build up on a general purpose breadboard. To
develop this circuit, basic electronic components like resistors,
diodes, LEDs and are used.
• By using this circuit, different faults can be checked like to know
whether the condition of a transistor is good or not, and opened
or shorted.

14. THANK
YOU