I'm outfitting my elderly mother's home with a series of sensors that allow me to track her activities. The system, which uses my own software to analyze events & states, sends emails to my cell phone when something anomolous happens.
One of the things I need to track is whether she left the water running somewhere. For this I need a sensor that can detect that water is flowing in a pipe, and transmit a corresponding state message to the automation software system. I don't see anything cheap & readily available, so I've resorted to rolling my own.
My plan is to use a cheap EagleEye motion sensor (they're available in 3-packs for about $20 on Ebay) as the starting point. I would replace the pyro sensor with a remote microphone which would be affixed to the outside surface of a pipe near a point where water turbulance would cause a detectable sound. Next to the water meter or a valve would be likely monitoring points. I would modify the EagleEye circuit very slightly so that the output of the microphone would trigger an RF message, just as the output of the pyro detector would in the original EagleEye design.
The same technique could be used to measure that electric current is flowing in a wire (say the oven/stove) by using a hall-effect transducer in place of the pyro detector.
Am I re-inventing the wheel on this, and would anyone like to offer suggestions?