Thank you, tautech and everyone who chipped in. We're in a respectable spot on the board.
I'm amazed we finally made it on the top-10 for views. This is definitely more of a participation thread than a look-around one, so I thought it'd take much longer than it has.
I think that's because word got out that we're pretty much the Monty Python of the board; people tune in just to see what the next train wreck is gonna be like...
We've certainly perfected the "and now for something completely different" part.
Yep big time so........
Potted non History. I am an EE who worked with Pumps and Control Systems .................
Bean:
I wanna add some simple dry run protection to that new multistage pump.
I was thinking about using an old style membrane pressure switch that’s Normally Closed when pump is OFF and use a timer to keep the pump ON and give say 2s delay after which it goes Open when the pressure is sensed and the pump stays ON and bypasses the ON timer.
I have LV RF control circuitry and cascading relays before the 3 phase contactor where I can cut this circuit into the LV (12V) ON/OFF relay.
We looked at PLC’s and flow and pressure sensors today but crazy $$$ so being cheapskate and wanting to KISS so I’m looking for a real simple timer method to have a lock out after 1-2s if the pump doesn’t supply pressure/flow. A pressure check shows me it’s pumping to ~100 PSI.
So what best could/should it be ?
555 + bipolar relay driver ?
RC and a single bipolar ?
One shot IC ?
Monostable timer ?