I have another thread where some forum members have helped me formulate my thinking on a project, and as we've made our way through the "big picture" questions I've come to realize that I might be better served by asking some of the smaller questions in their own threads, so I'm creating a few. For reference, here is the "root" thread: https://forum.allaboutcircuits.com/threads/high-speed-actuation-sensing.159382/
Groundwork: I want to trigger a timed pulse in response to an SPST switch going low. The switch would stay low, and this needs to not affect the pulse (i.e., the pulse still needs to end, even though the trigger is still low). Currently I'm looking at the 555, mainly because it was the first thing suggested by a friend of mine, but in reading about it I'm coming to the conclusion that it won't behave this way on its own.
Questions:
Groundwork: I want to trigger a timed pulse in response to an SPST switch going low. The switch would stay low, and this needs to not affect the pulse (i.e., the pulse still needs to end, even though the trigger is still low). Currently I'm looking at the 555, mainly because it was the first thing suggested by a friend of mine, but in reading about it I'm coming to the conclusion that it won't behave this way on its own.
Questions:
- Is it true that in monostable mode for the 555, if the trigger goes and stays low, the output pulse won't end after the timer runs out?
- If the above is true, how can this behavior be made compatible with a trigger that stays low?
- If it can't be made compatible, what are some other options (other approaches, other ICs, etc.)?