Application of UJT as a relaxation oscillator.

Experiment No.: – 02

Aim of the Experiment: –

Application of UJT as a relaxation oscillator.

Objectives: –

  1. To study the condition of a UJT.
  2. To comprehend the working principle of the UJT.
  3. To study the behavior’s of a UJT as a relaxation oscillator.
  4. To study the application of a UJT as a relaxation oscillator.

Apparatus Required: –

Sl. No.NameSpecificationQuantity
1UJT 2N2646PIV=8V Valley Voltage=1.5V1 no.
2DC power supply10V1 no.
3Potentiometer (POT)100K1 no.
4Capacitors0.47µF
0.22µF
0.1µF		1 no.
5Resistors1K
680Ω
62Ω		1 no.
6SwitchesSingle pole toggle (S1)Three way selector (S2)1 no.
7CROSingle Beam 15MHz1 no.
8MultimeterDigital1 no.
Table No. 2.1

Circuit Diagram: –

Fig. 2.1

Theory: –

Fig. 2.2 : Wave Form For UJT as a Relaxation Oscillator.

Procedures: –

  1. Make connections as per the circuit diagram.
  2. Keep the potentiometer (POT) at its minimum resistance position.
  3. Connect the 0.1µF capacitor in the network with the help of switch S2.
  4. Connect the CRO at the output across the 62Ω resistor.
  5. Switch on the 10V d.c. supply with the help of switch S1.
  6. Observe the pulse pattern of the relaxation oscillator on CRO by varying the POT and trace the patterns at different values of resistance. Also note down the amplitude and width of the pulses.
  7. Repeat steps No 2 to 6 by connecting the 0.22µF and 0.47µF capacitors separately by means of the switches.

Observation Table: –

Sl. No.Amplitude of the pulse (mV)Pulse width (µ sec)Relaxation time (µ sec)Pulse Pattern
1.For 0.1 µF Capacitor   
2.For 0.22µF Capacitor   
3.For 0.47µF Capacitor   
Table No. 2.2

Precautions: –

  1. Components used in the circuit for conducting the experiment should be checked and tested thoroughly with the help of a multimeter, before connecting them in the circuit.
  2. Peak inverse voltage (PIV) and valley voltage (VV) of the UJT should be confirmed from data manual and the power supply range should be chosen accordingly.
  3. Current limiting resistor (10K) and the POT (100K) connected in the circuit should have proper ratings depending on the PIV and VV ratings of the UJT used.

Conclusion: –

Written by student.

Previous
Next