water sensor

**scott_fx** · 01-15-2009, 12:20 PM

Hey guys,

I'm toying around with the idea of having a computer controlled ballast system in my boat. I want this to be fully automatic and therefor would need a way to tell the computer when the tanks are full and to stop pumping. I think that tapping into the overflow would be the easiest way to 'sense' when the tanks are full. Basically.. when they tanks fill up, they'll start evacuating the flowing water out of the overflow port. if i could put something there that could sense the water then it could tell fb to shut down the pumps.

does anyone know of sensor that would fit my needs?

**greenman100** · 01-15-2009, 12:33 PM

2 contacts and a darlington pair

ala here:

http://www.zen22142.zen.co.uk/Circui...waterrelay.htm

**scott_fx** · 01-15-2009, 12:45 PM

that is perfect... thanks!

**scott_fx** · 01-15-2009, 12:51 PM

just a thought since i have some of these ic's laying around but, could you also use a qprox capacitance switch to sense water?

**greenman100** · 01-15-2009, 01:00 PM

i guess but a darlington pair is like 20 cents

**scott_fx** · 01-15-2009, 01:02 PM

fair enough

**greenman100** · 01-15-2009, 01:22 PM

yeah, the problem is that you'll encounter some issues with residual moisture being enough to trigger the circuit.

really you probably want a cheap flowmeter like this, with a LED/phototransistor

http://cgi.ebay.com/Rate-Meter-Serie...3A1%7C294%3A50