I want to know if there is a simple (and cheap) way to make a momentary button (for which we cannot control the time it holds when pressed!) press to virtually hold for about 1-2 seconds.

More precisely, I want to implement a low power consuming solution for a monostable-"mode" 555 timer. Thus when the button is "hit", the 555 Vcc pin will go HIGH for at least the amount of time required for one pulse to be sent out. After that the circuit will go back to stable 0V, until next hit.

Even more precisely - The pulse is used to move a small servo to a certain, constant, predetermined position.

  • \$\begingroup\$ Something like an SN74LVC1G123 will do the monostable function with possibly less power consumption than a 555. But is the (C)555 really so high power that it makes a difference, compared to the power needed to drive your servo? \$\endgroup\$
    – The Photon
    Commented Dec 10, 2013 at 22:36
  • \$\begingroup\$ You should put the details about your experience with electronics in your profile. \$\endgroup\$
    – David
    Commented Oct 21, 2014 at 16:18

1 Answer 1


It's called a non-retriggerable monostable. Here's one that isn't a 555 just to show that there is life beyond that ubiquitous animal: -

enter image description here

The 555 timer is fairly adept at most things in the timer bracket so maybe try searching for "555 non-retriggerable monostable". Here's a circuit but I'm no expert on 555s

  • \$\begingroup\$ I meant that not necessarily the pulse will go once, but the important thing is that the chip itself will take next to nothing of current when it is in stable 0v mode. \$\endgroup\$
    – nitzpo
    Commented Dec 11, 2013 at 9:06
  • \$\begingroup\$ @nitzpo the HC device listed above is another avenue to follow in looking for low current solutions if 555s are not low enough. The device above takes 600uA max and may not be low enough but apart from this and the 555 I know of no lower solutions. \$\endgroup\$
    – Andy aka
    Commented Dec 11, 2013 at 9:42
  • \$\begingroup\$ Ain't there a solution where the whole chip is 0v until click? Some other component will release enough power for the chip to pulse when connected. \$\endgroup\$
    – nitzpo
    Commented Dec 11, 2013 at 9:53
  • \$\begingroup\$ @nitzpo do you mean the power to be applied to the ic whenever the button is clicked;after the specified time period the ic should again powered down is it like that? \$\endgroup\$
    – yogece
    Commented Feb 9, 2014 at 6:55

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.