conditional switching

Hello,

It sounds like what you need is similar to the "short-cycle timer" found in HVAC systems, which works like this: Once the A/C compressor shuts off, it's not allowed to run again for about five minutes, even if someone nudges the thermostat. If that's the sort of operation you're looking for, the circuit below provides a 30 mS short-cycle timer.

The One-shot Fall / Reset goes high when the input falls. This inhibits the output via the Zero Comparator and AND Gate. Once the Timer counts 1440 samples (30 mS), it times out which resets the One-shot, thus enabling the output.

The scope photo below shows the result -- If the input hasn't been high within the past 30 mS the output would respond instantly to a new high input; however with the repetitive input shown, it delays for 30 mS after the input has last gone low:

Best regards,

Bob

Short-cycle.zip

Hello,

Thanks Bob.