Set/reset buzzer 2
Électronique / Electronic

Here's another version of our last Project Set/reset buzzer 1, this time using a transistor multivibrator and a J-K flip-flop.

Set the Select Switch to A before setting the Control Knob to ON, When you do set the Control Knob to ON, press the Key. You'll hear a sound in your Earphone. Just as in our last Project, you'll continue to hear sound in the Earphone no matter how many times you press the Key again.

Set the Select Switch to B and press the Key one more time. You'll hear the sound stop.

You can see from the schematic that The transistor multivibrator is controlled by the Ǭ output of the J-K flip-flop.

When you have the Select Switch at A and press the Key, Ǭ will be 0 and the transistor multivibrator will keep on working regardless of how many more times you press the Key.

But if you press the Key when the Select Switch is at B, Ǭ becomes 1. This output goes to the emitter of the left Transistor in the multivibrator and prevents the multivibrator from working.

(We've mentioned this before -but well say it again. Aren't transistors terrific in the way they can be switched on and off so easily?)








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