Dynamic Test of the Unijunction Transistor (INS034E)

Unijunction transistors (UJT) are basically used as relaxation oscillators. We can do dynamic testing of these transistors with the procedure that we will explain below. For the test, we will need to set up a test circuit and have the following instruments:

a) Oscilloscope or multimeter



B1 - 9 to 12 V source

R1 - 10 k ohm x 1/8 W - resistor

R2 - 470 k ohm x 1/8 W - resistor R3 - 100 ohms x 1/8 W - resistor

P1 - 1 M ohm - potentiometer

C1 - 10 nF for the oscilloscope or 1 uF for the multimeter



The test circuit is given in the figure below.






By adjusting P1 we should observe the oscillating instrument needle or the waveform generated on the oscilloscope screen.