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Circuits designed by David Johnson, P.E.
Last Updated on:
Friday, March 23, 2012 08:39 AM
Master Category List -
Dave's Circuits
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Liquid Sensors / Detectors |
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Electrodeless 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 than the upper coil, no signal is coupled between the
coils. Once calibrated, this technique might also work on the outside of
a plastic water tank. (added 7/06)
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- 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. Drawing only 6uA, the whole circuit is powered by a lithium coin
battery, which should power the circuit for many years....
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WATER SEEPAGE ALARM
This simple circuit sounds a beeper when its electrodes detect water. A single 1.5v N
cell powers it. A small 1.5v button battery will also work.
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