need a simple RC time circuit

Thread Starter


Joined Nov 21, 2009
I need to build a time delay circuit that when the bilge float switch opens (opens the circuit) there will be a time delay from the pump turning off . The reason I need this is to stop the constant on/off cycle of a bilge pump turning on and off with the float switch bobbing up and down.
The pump is 3 amps and 12 volts. I am working on a ball park figure of a 10 second delay from when the float switches and the pump stops. I pucrchased a 100K pot and a 100uf cap right T=R*C so 100,000*.000100 = 10Sec right ? the problem is I am not sure what to put where? Does this all go in series or parrell with the power source? Where does the pump hot 12V side go?

Any help would ne great




Joined Jul 17, 2007
Hi Wetbar,
Welcome to AAC.

Haven't been sailing for awhile, but am not unfamiliar with the problems of sailors, sailboats, and bilge water.

First, is there any way that you could re-locate either the pump or the switch to be further apart from one another? Actually, just relocating the switch from the immediate location of the deepest part of the bilge would help a great deal.

You really don't want to have to add any complexity, unless it's entirely necessary.

Thread Starter


Joined Nov 21, 2009
yup I agree, but I have moved and replaced the pump and the float switch. I even raise the switch on a two inch platform so it would take on more water before the pump came on. The only thing I can think of is adding a RC circuit.


Joined Aug 7, 2008
Could put switch an a container which has small hole, so that container water level represents the average bilge level, eleminating wave action.