water level sensor

hello. I need to make a level sensor for a small amount of water (2 litre bottle) to attatch to an arduino to control a motor. I need help with what sort of sensor I shoud use. Any suggestions? It needs to have a low and high sensor, 1 normally open, the other normally colsed.

cheers

Wow, There are so many options! If you need great reliability go with a comercial sensor (and there is a bewildering array of them) Check out McMaster.com If you are making your own consider these ideas. -A Sharp IR distance sensor looking down to the liquid -same Idea with a sonar sensor -A float with a magnet and a hall effect sensor (sensors can be found with open collector and ttl outputs) -Not green but you could find an old thermostat with a Mercury switch and put it on a tilting float -Lots of circuts that use the conductivity and/or capacitance of the water are available on the internet. -if you are actually using a 2 liter bottle you could arrange opto sensors to look through the bottle and note the change in transparency. Figure out your needs and take a pick

cheers for that Kirk. will figure out which road to travel down now.

Kyp

If I use a Sharp IR distance sensor looking down to the liquid, is there a best one to use for detecting maximum distance of 30cm, minimum distance of 4cm?

cheers

K

I just saw an interesting homemade water level sensor in Nuts and Volts magazine. The author used two strips of aluminum tape to not quite complete a circumference of a water container. He then attached wires to the conductive tape and formed a capacitor. Using a timed RC circuit where the C is the water level capacitor he could indicate when the container was full.