One shot is a monostable multivibrator, it is normally in a stable state but once triggered it changes to an unstable state.

But I can't understand the difference between a nonretriggerable and a retriggerable One shot.

Can somebody please help me understand it ?


2 Answers 2


In a retriggerable MMV a new trigger during a pulse will restart the pulse time, and thus extend the current pulse.
If the pulse time is 10 s and you would retrigger 6 s after the first trigger you would get a 16 s pulse.

enter image description here

In a non-retriggerable MMV the second trigger will be ignored and you'll get a 10 s pulse:

enter image description here

  • 1
    \$\begingroup\$ It's worth noting that in a retriggerable device, there is a time relative to the falling edge of Q (could be before or after) before which a retrigger event is guaranteed to be ignored, and a later time (could still be before the falling edge of Q) after which a retrigger event is guaranteed to be effective. Trigger events occurring between those times may be ignored, may start a normal interval, or may start a "runt" interval, or may behave oddly (possibly causing an interval which starts or ends later than expected). \$\endgroup\$
    – supercat
    Commented May 7, 2012 at 16:51

This concerns the circuit's response to additional trigger pulses while it's in a triggered state (is outputting a pulse). In a retriggerable monostable, additional input pulses will extend the output pulse by keeping the circuit in the unstable state, while in a non-retriggerable one they will have no effect. See wikipedia.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.