DIAC

AIM-

To study the VI characteristics of DIAC with positive biasing and plot the curve between V and I.

APPARATUS-

NV6531 Diac Characteristic Trainer, 2mm Patch Cord

THEORY-

The diac is a two-terminal device that has three semiconductor layers. It is a bidirectional diode,

i.e. it can be made to conduct in either direction. This is just like a TIRAC without a gate terminal. The switching from OFF to ON state can be achieved by simply exceeding the avalanche breakdown in either direction..

CIRCUIT DIAGRAM-

PROCEDURE-
POSITIVE BIASING

1. Make the connections as same as the circuit diagram.
2. Connect the +35V DC supply to the circuit by connecting point 1 with point 4 with the help of a patch cord.
3. Rotate the potentiometer P1 in the fully anti-clockwise direction.
4. Now connect point 2 with point 8 to make grounds common.
5. Connect the voltmeters across the DIAC. For that connect the posiitve terminal of voltmeter with the point 7 and connect the negative terminal with point 8.
6. Now connect the Ammeter to the point 5 and negative terminal to the point 6.
7. Connect the mains cord to the trainer and switch on the supply.

NEGATIVE BIASING

1. Connect -35V DC Supply to the circuit by connecting the point 3 and point 4.
2. Repeat the process from steps 3-7.
3. Now plot the VI curve for taken readings.

OBSERVATION TABLE-

POSITIVE BIASING		NEGATIVE BIASING
DIAC Voltage (in V)	DIAC Current (in mA)	DIAC Voltage (in V)	DIAC Current (in mA)

RESULT-

VI characteristics of DIAC in both positive and negative bias are obtained.

In forward bias, the current increases after    V, and in the reverse bias, the current increases after –         V.

PRECAUTIONS-

1. Connections should be tight.
2. Avoid double connection.