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Sensors / Detectors: Water / Moisture Sensors
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Sensors / Detectors -- Main Page
Last Updated on: Tuesday, April 01, 2014 04:29 AM


Circuits designed by Dave Johnson, P.E. :

  • 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)
     

  • Doggie Water Dispenser Alarm
    I have two Beagle dogs.  They drink a lot of water; they go through about 3 gallons a week.  They have two water dispensers.  One is on the inside and second unit on the outside of my house.  Often, I forget to fill one of their two jugs and discover them completely empty.  I do worry that my dogs might get dehydrated if I ever forget to fill both of their containers.  To help prevent this, I decided to design and build a battery powered alarm system which would monitor the level of water in the jugs and sound an alarm when the water level dropped below a certain volume....

  • Water Flowing in Pipe Indicator -- July 6, 2009
    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....
  • 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.


Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:
12 Volt Toilet Tank Refiller -  A flushing toilet is something that most city dwellers take for granted, but it can be a luxury for those who live away from utility water and electricity.  This circuit provides on-off pump switching for a small 12 Volt pump that is used to fill a toilet tank from an external rain water collection cistern. The 12 Volt power comes from a small solar power system. The cistern is located at ground level, so the pump is required to move the water up to the toilet tank.... [G. Forrest Cook]
AN1013: Gas & Water Metering with the PIC16F91X Family -  Microchip Application Note Published 20-Jan-06  (app note added 2/06)
Christmas Tree (or other plant) Moisture Monitor -  Originally intended to monitor the moisture in a potted plant, this moisture monitor really shines as a Christmas tree stand water level monitor! A fresh Christmas tree drinks water an annoying rate and bending down under the decoration-laden branches....(electronic design added 7/08)
Doggie Water Dispenser Alarm - I have two Beagle dogs.  They drink a lot of water; they go through about 3 gallons a week.  They have two water dispensers.  One is on the inside and second unit on the outside of my house.  Often, I forget to fill one of their two jugs and discover them completely empty.  I do worry that my dogs might get dehydrated if I ever forget to fill both of their containers.  To help prevent this, I decided to design and build a battery powered alarm system which would monitor the level of water in the jugs and sound an alarm when the water level dropped below a certain volume....(circuit of the week designed by David Johnson, P.E.)
Gas & Water Metering with the PIC16F91X Family -  Microchip Application Note Published 20-Jan-06  (app note added 2/06)
Hot Water Tank Indicator -  The idea for this project may have come to me in a flash of inspiration, and its a very simple way to check if a fuse has blown without removing it from its holder….(circuit / design added 8/03)
One wire bus powers water level sensor -  02/15/00 EDN-Design Ideas....remotely monitor the level of liquid water in a vessel such as a swimming pool.... EDN is migrating links. This link is not verified.  Google the "title" EDN for new link.
Plant Moisture Meter -  Stick the metal probes into a freshly watered plant and adjust R5 for a mid-scale meter deflection. The meter will monitor the soil wetness and the meter will indicate whether it is to moist or to dry.  This circuit uses a dual power supply which could be created by two 9 volt batteries…. [Randy Linscott's circuit]
Plant Moisture Monitor -  (circuit / design added 8/03)
Pot Plant Power -  All plants carry an electric charge relative to the ground.  This charge is more or less constant regardless of the size of the plant a kind of background voltage" in nature.  This electric charge suffuses the entire plant, from its roots to its leaves and fruit. It was measured between a chrome-plated pin inserted into the plant....(added 6/03) [Circuit designed by Rev. Thomas Scarborough]
Pot plant water Tester -  ....
Rain Alarm -  This circuit consumes no current until moisture is detected on the rain plate. 
Rain Alarm -  This circuit gives out an alarm when its sensor is wetted by water. A 555 astable multivibrator is used here which gives a tone of about 1kHz upon detecting water. The sensor when wetted by water completes the circuit and makes the 555 oscillate at about 1kHz. [Radioland.nt.au]
Rain Detector (Aaron Cake) -  This circuit uses a sensor made of a small piece of etched PC board and a simple SCR circuit to detect rain and sound a buzzer. The SCR could also be used to activate a relay, turn on a lamp, or send a signal to a security system.  (circuit / design added 8/03)
Shower Stopper -  (circuit / design added 8/03)
Sump Pump Controller - Every sump pump controller that I have seen on the web uses DC to sense the water.  This approach is simple, but eventually causes corrosion of he sensor probes due to the electrolysis.  The probes than have to be periodically cleaned or replaced.  This circuit solves the problem by using AC to sense the water in the sump....[Designed by Andrew R. Morris]

Sensors / Detectors: Water / Moisture Sensors:   #'s - S        W - Z
Sensors / Detectors -- Main Page


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