How to Make a 555 Retriggerable

Thread Starter


Joined May 3, 2019
I would like to know what kind of strategies might exist for making the 555 timer retriggerable. I want to be able to restart the timer with a second pulse to the trigger input, extending the duration of the HIGH on the output. Is it possible without giving a high to the reset input, or is there a neat way to feed the reset input a high each time I hit the trigger?


Joined Mar 30, 2018
Here is a re-triggerable 555 timer circuit from my 555 cookbook.

The circuit works by discharging the timing capacitor each time a trigger pulse is applied to pin 2 of the 555 timer.Re-trig 555.jpg