A 556 would do it.
I have a (septic) pump that's triggered by a switch inside a float. Level rises, float rises, switch closes, pump turns on, level falls .. a wee bit, just enough to lower the float .. the pump turns off.
I want some hysteresis; switch closes, pump turns on, switch opens, pump STAYS on for another 30 seconds.
Timing is not that critical .. 25 seconds, 35 seconds, close enough. A uController is certainly an option and as a long time uController programmer, is how I'd usually do it.
HOWEVER, this is a mission critical application, and so the simpler the better; simpler still, better still. 555s are about as simple an option as could be, and are pretty well understood. Add a solid state relay, pretty much done!
But as a guy who built his first 555 circuit about 40 years and has built a whole lot over the years, I am embarrassed to admit I don't know how this circuit works!
I've simulated it and it does seem to work; I can reproduce the traces shown here.
But 555s are triggered on a negative going pulse. These traces show the output of the second 555 going high when the input goes high ...
What am I missing?
Alan