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Multivibrator » Electronics » Basic Circuits » Multivibrator » Let's go... » Experiment 10 - Warning Blinker

Experiment 10 - The Warning Blinker

Look at the circuit shown. You notice the extra push-button switch S1. In addition, the circuit has only one LED

Circuit of a warning blinker. (Enlarge)

Circuit diagram of a warning blinker.

As long as the push-button switch S1 is pressed, the multivibrator remains quiet. The LED is out.

By contrast, if you unpress S1, the LED1 starts to blink.

In a real world application, the push-button switch could be replaced by a trip wire or a contact at a door. When the trip wire is broken or the door opened, it is indicated by the flashing light of the LED.