Pete, do you have a datasheet link for your LPFS and HPFS? I'd like to see their
electrical requirements and what position feedback, if any, they offer.
Yes, latching relays could definitely be part of the solution, but they can't be
driven directly by the fuel level sensors. This type of relay requires a brief
pulse (a few tens of milliseconds) to set or reset its coil(s) (some have
two), not a continuous current like a normal relay. This would require some electronics
to turn the long-duration on/off cycles of the level sensors into these
short pulses.
Also, we want the absence of fuel at the Low Level Sensor to open the solenoids,
but we don't want them to close when that sensor sees fuel again; they have
to wait until the High Level Sensor also sees fuel. That's going to require some
electronics too.
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http://forums.matronics.com/viewtopic.php?p=516881#516881
