I got annoyed when I find how much auto bilge
pumps cost. They charge something like $20 extra just to make them automatic, and I didn't even like how they work, they cycle too much and the one I had quit working after a few months. The pump is fine after 2 years.
I took a float switch I got off the internet
for $3. You can get 2 for $5 on ebay if you search for float switch. They are only good for half an amp so can't drive a pump directly, not that you would want to anyway.
So I screwed the float switch inside the end of a pvc pipe with a cap on the end with a small hole 1/16 in hole in it to let water
in and out, and the larger hole at the top for air. The idea here is to avoid the sloshing, but it could potentially become clogged, so maybe multiple holes is preferable.
Then I run the float switch wires to trigger a 555 timer chip, and set to to 20 seconds time constant with 10uF cap and 2M ohm resistor. This way the pump always runs 20 seconds when it is triggered from the float, so I can position the float a bit higher in the bilge
. I put some leds to indicate pumping, and float sense so I get some feedback, and then have the 555 drive a mosfet which is wired to the pump. I also have a switch so I have manual on and off. The most expensive part here is the switch, so everything cost under $3.
I think this works pretty well, but I have yet to do any extensive testing. Problem is, I fixed all my below waterline leaks
, and I don't take too much water
from rain either!
What do you think? Any ideas for simpler or more reliable ways?
Any ideas for just using two wires going into the bilge to detect conductivity and trigger the pump that way? Would you need an opamp for this?