Comparator with hysteresis LM324
Electronic

Do you always take the same route on your way to and back from school?

Maybe you do so usually, but you must certainly have taken some other route for a change from time to time, haven't you?

Well, current which can be made to flow back by a route different from the going route in a circuit, and we're going to find out how in this project. The difference between the going and returning routes is called the "hysteresis." In this experiment, we're going to build a comparator with the hysteresis characteristic.

First, turn the control volume fully counterclockwise, and turn the power ON. The LED goes out.

Now, turn the control volume clockwise, and the LED lights up at some point. Note this point.

Next, turn the control volume clockwise and then slowly back counterclockwise, and check where the LED goes out. Did you notice the difference between the point where the LED lights up and the point where it goes out?

That's the hysteresis, and its width becomes larger when RA is increased or RB is decreased.