Sensors / Detectors: Liquid Detectors

Sensors / Detectors: Liquid Detectors
Sensors / Detectors -- Main Page
Last Updated on: Monday, October 03, 2011 06:07 PM

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)

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....

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]

Adjustment Free Inclinometer operates on 27V - 4/24/97 EDN-Design Ideas....The circuit in Figure 1 is an inclinometer (tilt-measuring circuit] in which the sensor is filled with liquid electrolyte. Acting like a potentiometer, this sensor produces a voltage proportional to the tilt on the center electrode. Because the liquid is subject to electrolysis, the sensor must have an ac-forcing voltage with an average dc component of zero.... [Design Idea by John Wettroth, Maxim Integrated Products, Sunnyvale, CA]

AN1013: Gas & Water Metering with the PIC16F91X Family - Microchip Application Note Published 20-Jan-06 (app note added 2/06)

Circuit provides ISFET-sensor bias - 10-Jun-04 Issue of EDN ISFETs (ion-sensitive field-effect transistors] are useful for measuring the acidity of fluids. Accurate measurements require that the ISFET's bias conditions (ID and VDS] be held constant while the gate is exposed to the fluid under test. The acidity of the fluid changes the channel width, resulting in a gate-source voltage, VGS, that is proportional to the fluid's pH.... [Design Idea by Brian Harrington, Analog Devices, Wilmington, MA]

Doorbell transformer acts as simple water leak detector - 15-Dec-09 Issue of EDN Doorbell transformer acts as a power supply.... [Design Idea by Jeff Tregre, www.BuildingUltimateModels.com, Dallas, TX]

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. [Designed by David A. Johnson, P.E.]

Fluid Level Detector - The above circuit uses an AC-sensing signal to eliminate electrolytic corrosion on the probes. The AC signal is rectified and used to drive Transistor T1 that drives the relay. The relay is a 12-V type of your choice. Transistor T1 can also be a TUP…. [Tony van Roon's circuit]

Fluid Sensor & More - It Can Detect Most Liquids and more....(design added 12/08)

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.

Piezo crystal monitors liquid level - 03/30/00 EDN-Design Ideas....The simple and inexpensive circuit in Figure 1 monitors the liquid level in a container. The piezo crystal, carefully mounted at the bottom surface of the container, receives it activation from the 74HCT14 hex Schmitt trigger. The….PDF contains multiple circuits, please scroll to find this one.... [Design Idea by J Jayapandian, IGCAR, Tamil Nadu, India]

Precision tilt/fall detector consumes less than 1.5 mW - 3-Dec-09 Issue of EDN Detect X-axis position and indicate it with an LED.... [Design Idea by Marián Stofka, Slovak University of Technology, Bratislava, Slovakia]

Tilt/fall detector has staggered thresholds - 18-Feb-10 Issue of EDN Comparators and a voltage-divider network let you set threshold levels.... [Design Idea by Marián Stofka, Slovak University of Technology, Bratislava, Slovakia]

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....[Designed by Dave Johnson]

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

Water-leak detector uses 9V batteries - 05/27/10 EDN Design Ideas....The design uses Maxim Integrated Circuits ' MAX934, an ultra-low-power quad comparator with a built-in 1.2V reference. The chip uses about 6 μA. IC 1A , R 1 , and R 2 provide water-leakage detection. R 1 is the water probe, which can be two bare copper wires wrapped in a sponge. R 1 has high impedance when the sponge is dry, so IC 1A 's output stays high.... [Design Idea by Yongping Xia, Navcom Technology, Torrance, CA]

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

Water-Level Controller - ....

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 & Control - This is a simple but reliable circuit for your sump-pump, aquarium, boat, or whatever, but water only. Please be careful when working with 115Volt line voltage! Take every precaution to avoid electrical shock. Unplug the power before making changes or touching resistor R1. Murphy's Law applies to all of us!…. [Tony van Roon's circuit]

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. [Circuit designed by David A. Johnson, P.E.]

Sensors / Detectors: Liquid Detectors
Sensors / Detectors -- Main Page