Piezoelectric Water Flowing Indicator  -  The vibrations associated with water flowing through a pipe are picked up by an inexpensive piezo wafer.  The signal from the wafer is first boosted by a micropower transistor amplifier and then fed to an ultra low power voltage comparator . . . [Hobby Circuit designed by David A. Johnson P.E.,  07/26/09]

Water Cistern Level Alarm  -  I received an unusual request from a Discover Circuits visitor a while back.  The guy had a deep water cistern which has to be filled when nearly empty. The cistern was described as a deep cylindrical tube, holding 1000s of gallons of drinking water.  Periodically, the cistern is filled from a tanker truck, when the water inside reached a critical level.  The guy wanted a simple circuit he could build which would flash an LED when the water level reached a certain depth.  That flasher would tell him it was time to order more water . . . [Circuit by David A. Johnson P.E.,  04/27/14]

Water Filling Station Controller  -  This circuit was requested by a company needing a simple way to fill a large tank with water with little fuss.  They wanted a low tech method to automatically fill the tank with water without constant monitoring.  They wanted to press a single pushbutton switch and then walk away . . . [Hobby Circuit designed by David Johnson P.E.,  04/24/11]

Water Flowing in Pipe Indicator  -  The vibrations associated with water flowing through a pipe are picked up by an inexpensive piezoelectric wafer.  The signal from the wafer is first boosted by a micropower transistor amplifier and then fed to an ultra low power voltage comparator.   When the vibration signal has sufficient amplitude, a FET transistor switch is activated…[Circuit designed by Dave Johnson P.E., 6/06/2009] . . . [Circuit by Dave Johnson P.E.,  07/26/09]

Water Level Monitor  -  This system operates much like a classic float switch but without any moving parts.  The illustration shows how a system using two copper coils sealed inside a plastic pipe, can detect the level of water outside the pipe.  Whenever the water level is lower . . . [Hobby Circuit designed by David Johnson P.E.,  07/09/06]

Water Seepage Alarm  -  This simple circuit sounds a beeper when its electrodes detect water. It is powered by a single 1.5v N cell. A small 1.5v button battery will also work . . . [Hobby Circuit designed by Dave Johnson P.E.,  06/11/00]

Water Seepage Monitor  -  A while back I received a request from a company who needed a water seepage detector.  They wanted a device that ran on 24vac and detected water using a fully isolated circuit.  They wanted a circuit which switched off 24vac to a load when water was detected . . . [Circuit by David A. Johnson P.E.,  01/16/11]