SYNCHRONISED UJT TRIGGERING CIRCUITTO TURN ON SCR

AIM: To study the performance of a Synchronized UJT triggering circuit for Half Wave Rectifier and to plot relevant waveforms. APPARATUS:

Sl. No. APPARATUS RANGE QUANTITY

1 UJT firing Module 2N 2646 17 CRO --- 13 REHOSTAT 0-200 OHMS 14 Patch chords --- 1

CIRCUIT:

R

R b2

1k

R c

C

1n

TX3

R a

1k

230V 50H z A C S up p ly

R ec tifier V o ltage R egulato r

V a c

0 - 2 0 V A CA

KG

0 - 2 0 0 o hm s/2 A

E

B 2

B 1

D 1

D 2D 3

D 4V z

Zen

er D

iode

SCR

TY

N61

2

2N26

46

15v/

1W

1 0 0 m ic ro f/ 3 5 v

1 :12 3 0 v:2 0 V

C irc uit d iagram o f U JT as relaxatio n o s c illato r

Theory:

Procedure:

1. Make connections as shown in circuit diagram.

2. Switch on the supply to the module

3. Observe the wave form and note down the corresponding reading at different

points in the circuit (at supply terminal, rectifier output zener output , across

capacitor , across emitter and base B1 of UJT).

4. Supply anode to cathode of SCR alternating supply voltage vary the firing angle

of SCR with variable resistance RC( in module) in steps and at each step observe

and note down the voltage across various node.

5. Switch off the supply.

Observation:Sno Alpha(α) Vout in volts Beta(β) Vdc in volts

Waveform:

Waveforms of UJT relaxation and waveforms across SCR and load.

Conclusion: