Schmitt Trigger Using Op-Amp

Experiment 7

Aim:

To Construct and test an inverting Schmitt trigger circuit using op-amp 741.

Apparatus Required:

SL. No	Name of the apparatus	Range	Type	Qty
1.	Regulated Power Supply	+/-12V	DC	1 No
2.	Resistors	10K Ohm		3 No
3.	Operational Amplifier		IC 741	1 No
4.	Function Generator			1 No
5.	CRO			1 No
6.	Breadboard			1 No
7.	Connecting wires			Required Amount

Theory:

• In them the input is given to the inverting terminal. Hence the output will be 180° out of phase with the input. The positive feedback is given to the op- amp. The reference voltage is set by means of the resistor R2 and is given to the non-inverting terminal.

• When the input voltage is greater than the reference voltage, the transistor in them is driven to the saturation state. But the input is given to the inverting terminal and hence the input goes in the positive direction and the output in the negative saturation level. If the input goes in negative then the output will be in the positive saturation level.

Circuit Diagram:

Tabular Column:

Waveform	Amplitude (No. of div * Volts per div)	Time Period (No. of div * Time per div)
Input
Output
Vut
Vlt

Model Graph

Procedure

1. The op-amp inverting Schmitt trigger circuit is constructed according to the circuit diagram.

2. Adjust the signal generator to produce ±1V.

3. Sketch the input and output wave forms and the level of upper and lower trigger voltages.

4. Measure the output square wave with their amplitude and time period.

Link to experiment

Go here and select Experiment 7

Demonstration Video