555 Monostable Mode Press and Hold Trigger

Question

So, I have a 555 Timer in Monostable Mode, like below. I used a 47uF cap and a 47K resistor for the C and R. I press the trigger switch button and let go, and the output goes high for roughly 2.5 seconds, and then goes low. Just as would be expected.

Is there a way to make it so that when I press and hold down the trigger switch, but do not release it, that it outputs 2.5 seconds, and then goes low?

And if I let go of the trigger button and press it again, it starts over again?

Image from https://www.allaboutcircuits.com/tools/555-timer-monostable-circuit/

Answer 1

Try something like this:

^{simulate this circuit – Schematic created using CircuitLab}

That probably should be close to what you want, I think, without using two 555s.

Here's a simulated output:

I used a couple of button presses (red) during the first output pulse. You can see that it doesn't re-trigger and just holds the correct output time (green.)

In the second period starting at \$5\:\text{s}\$ there is a long-press used that exceeds the output period. But as you can see the correct output time is still maintained.

It's just a simulation. It's not proof. And I didn't think too long about it. So I may have missed an important detail, too. But this is about where I might go with your circuit as a first step in the right direction.

(Note: I didn't actually use a clean switch in the simulation. I used a very bouncy switch that was set to bounce randomly for about \$25\:\text{ms}\$, which is probably even worse and longer than reality. So I did try to make this closer to a worst-case switch input.)