April 14th, 2008 Water Level Alarm
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This is a circuit that offers visual indication of fluid level in a vessel, with a switchable audible alarm. Example uses would be to monitor the level of water in a bath, cold storage tank or even a big aquarium. How this works ? its simple, the circuit will trigger with any fluid with a resistance under 900K between the maximum separation distance of the probes. 4011 IC’s are cheap and easy to find, so you wont have any problems building this project.