One-shot multivibrator using J-K FLIP-FLOP
Oscillateurs   /    Oscillators
Électronique / Electronic

In this project, you are going to make an one-shot multivibrator using two J-K flip-flops.

When you finish wiring, turn power ON.

LED 1 is in a state of going off. At this time, press S1 once for a moment and LED 1 lights up.

The circuit holds LED 1 lit up for a certain period of time no matter how long you keep pressing S1. In the circuit, if S1 provides a trigger pulse for the first J-K flip-flop (hereafter, J-K FF), the output Q of U1A becomes H and which makes the LED 1 light up.

At the same time, the output Q of U1A becomes L. When a delay time set by the Rt x Ct time constant is passed, a trigger pulse comes in the second J-K FF U1B, which makes its Q output H and leads to resetting both the U1A and U1B.

As a result, the Q levels of the two J-K FFs become L so that LED 1 goes out. In short, when you press S1, LED 1 lights up and keeps on lighting for a period determined by a time constant Rt x Ct.

When you vary the values Rt and Ct, the time period of LED 1 being lit is changed.