"Offbreed" . wrote in message . A long time ago, I saw a circuit using a
silicon controlled rectifier
as a latching relay to control a bilge pump. It used two float switches
(one mounted higher than the other) and both had to be up to start the
bilge pump. The pump continued to run until the lower float switch
fell.

The advantages were that the back flow from the hoses did not cause the
pump to start again, and the low current demand allowed the switches to
last longer.

I cannot relocate the circuit,

Does this ring any bells? Anyone know where to find the diagram?

The only circuits I can come up with have the full pump current going
through the lower switch, unless I go to a mechanical relay.

Quickly, this isn't going to be any help, but once an SCR fires, (in a
DC circuit), it isn't easy to halt it's conduction without interrupting the
current flow by introducing another switching device.... are there trick
circuits that fool the SCR into turning off?
The other (non-helpful, I know) question is that if there is backflow
from the discharge hoses, shouldn't there be checkvalves to prevent seawater
from entering (especially during a moderate heeling turn?)
I'm wondering about the same pump control techniques, but this is at my
house when we have more than a little rain. Like this past week!
Old Chief Lynn