Monostable multivibrator
Electronic

Let's make a monostable multivibrator using one PNP transistor and one NPN transistor. The monostable multivibrator produces an output for a fixed time after receiving a trigger pulse. In this project, we're going to check this function using LEDs.

When you finish making the connection, turn power ON. You'll see LED 1 goes out and LED 2 lights up.

Now, press S1 just for a moment and see what happens. This time LED 1 lights up and LED 2 goes out, but both return to the former state in about one second.

This is the function of the monostable multivibrator. Because of this function, the monostable multivibrator is used to sound alarms for a predetermined time or to shape pulse waveforms. It is also used in many delay circuits.