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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)

• 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.

15 Volt Toilet Tank Refiller - (electronic diagram added 6/03)

AN1013: Gas and Water Metering with the PIC16F91X Family - Microchip Application Note Published 20-Jan-06  (app note added 6/06)

Circuit checks swamp cooler Water level - 10/31/02 EDN-Design Ideas:  A "swamp cooler" is an easy way to obtain effective air conditioning, especially in hot and dry climates, if a water source is readily available. Although most units are very reliable, the storage-reservoir control usually uses a single level-detector component. Failure of this component can lead to serious water damage.....(design idea added 1/05)

CMOS NAND gates control sump pump - 05/14/09 EDN- Design Ideas,  A similar circuit lets you control both the sump pump and the water level.....(design idea added 08/09)

Economical Pump Controller - Having a reliable system to pump out a sump pit is essential as mistakes and failures can lead to serious flooding and enormous expense. In our article Sump Pump Control System we introduced a selection of electronic solutions to the following problems....(circuit added 09/08)

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) ….(designed by David A. Johnson)

Gas and Water Metering with the PIC16F91X Family - Microchip Application Note Published 20-Jan-06  (app note added 6/06)

Infra-Red IR Beam Alarm/ Proximity Detector - This circuit can be used as an Infrared beam barrier as well as a proximity detector.  The circuit uses the very popular Sharp IR module (Vishay module can also be used). The pin nos. shown in the circuit are for the Sharp & VIshay modules. For other modules please refer to their respective datasheets.  The receiver consists of a 555 timer IC working as an oscillator at ... (added 11/06)

Infra-red Liquid Level Detector - Useful for liquids level detection and proximity devices Up to50 cm. range, optional relay operation (added 4/05)

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.....(design idea added 6/06)

Piezo crystal monitors liquid level - 03/30/00 EDN-Design Ideas:.....(design idea added 11/05)

Simple Sump Pump Controller - Having a reliable system to pump out a sump pit is essential as mistakes and failures can lead to serious flooding and enormous expense. In our article Sump Pump Control System we introduced a selection of electronic solutions to the following problems….(electronic schematic added 08/08)

Water Level Alarm (Andy Collison) - (electronic schematic / circuit added 4/02)

Water Level Control/Monitor - A simple way to control the level of any liquid in any container. (electronic schematic added 05/04)

Water Level Indicator with alarm - This circuit not only indicates the amount of water present in the overhead tank but also gives an alarm when the tank is full.  The circuit uses the widely available CD4066, bilateral switch CMOS IC to indicate the water level through LEDs. When the water is empty the wires in the tank are open circuited and the 180K resistors pulls the switch....  (added 10/05)

Water Level Reference Design - The Water Level Reference design continuously monitors water level and water flow using the temperature compensated MPXM2010GS pressure sensor in the low cost MPAK package, a dual op–amp, and the MC68HC908QT4, 8–pin microcontroller. This system uses very few components, reducing the overall system cost. (app note added 3/05)

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. ….(designed by David A. Johnson)

Water-level Alert - Beeper or flashing LED alert.  (electronic design added 6/07)

Water-Level Controller - (electronic Circuit / Schematic added 10/04)

Water-level Indicator - The whole project was developed on a friend's request. Its purpose was to remotely monitor the water-level in a metal tank located in the attic by means of a very simple control unit placed in the kitchen, some floors below. ….(electronic schematic added 11/08)

Water-level Sensing and Control - (Tony van Roon's electronic diagram added 6/03)

Waterpump Safety Guard for Fish-pond - The circuit below was developed to guard the fish pond.  In this case to prevent that the pump sucks just air when the water level get below the pump.  When the water filters get saturated and dirty, the water level behind the filter gets to an unacceptable level.  You can see this when the pump also produces air bubbles in the water... (Tony van Roon's electronic design added 2/06)

Wireless Liquid Level Sensing for Restaurant Applications - (circuit / schematic design added 6/06)