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Fluid Level Detectors / Monitors

Last Updated: November 30, 2017 10:30 AM

Circuits Designed by Dave Johnson, P.E. :

Capacitance Type Liquid Level MonitorThis circuit was originally designed to monitor the level of liquid natural gas in a tank but it can be used to also measure almost any liquid.  Two custom insulated metal tubes form a capacitor plate.  The capacitance between the two tubes increases as the level of the liquid rises . . . Hobby Circuit designed by David Johnson P.E.-June, 2000

Doggie Water Dispenser AlarmI 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. . . Circuit by David Johnson P.E.-June, 2012

Fluid Level MonitorThis circuit was originally designed to monitor the level of liquid natural gas in a tank but it can be used to also measure almost any liquid.  Two custom insulated metal tubes form a capacitor plate.  The capacitance between the two tubes increases as the level of the liquid rises. . . Circuit by David A. Johnson P.E.-June, 2000

Low Value Capacitance MeterThis circuit was originally designed to measure the volume of fluid inside a medical syringe.  As designed, it produces a zero to 5 volt output, corresponding to a capacitance change of about 10 picofarads. . . Circuit by David A. Johnson P.E.-December, 2004

Precision Low Capacitance MeterThis circuit was originally designed to measure the volume of fluid inside a medical syringe.  As designed, it produces a zero to 5 volt output, corresponding to a capacitance change of about 10 picofarads . . . Hobby Circuit designed by David Johnson P.E.-December, 2004


Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

Capacitance Type Liquid Level Monitor -  This circuit was originally designed to monitor the level of liquid natural gas in a tank but it can be used to also measure almost any liquid.  Two custom insulated metal tubes form a capacitor plate.  The capacitance between the two tubes increases as the level of the liquid rises . . . Hobby Circuit designed by David Johnson P.E.-June, 2000

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. . . Circuit by David Johnson P.E.-June, 2012

Fluid Level Control -  with LM1830 fluid level detector IC.   The LM1830 fluid level detector circuit is a device intended to signal the presence or absence of aqueous solutions, ___ hobbyteam @ hobby-hour.com

Fluid Level Monitor -  This circuit was originally designed to monitor the level of liquid natural gas in a tank but it can be used to also measure almost any liquid.  Two custom insulated metal tubes form a capacitor plate.  The capacitance between the two tubes increases as the level of the liquid rises. . . Circuit by David A. Johnson P.E.-June, 2000

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.   __ Designed by Tony van Roon  VA3AVR

Liquid Level Tach Transmitter -  Schematic  __ Designed by Jon Fick

Liquid Level Receiver  -  Schematic __ Designed by Jon Fick

Liquid Level Transmitter/Receiver SystE - M -  designed for marine applications using raytheon's seatalk®bus. Includes tachometer transmitter example although the receiver is only for liquid level (16f628)  __ Designed by Jon Fick

Low Value Capacitance Meter -  This circuit was originally designed to measure the volume of fluid inside a medical syringe.  As designed, it produces a zero to 5 volt output, corresponding to a capacitance change of about 10 picofarads. . . Circuit by David A. Johnson P.E.-December, 2004

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 __ Contact: Charles Wenzel of Wenzel Associates, Inc.

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 __ Designed by Rev. Thomas Scarborough

Plant Watering Watcher -  A flashing LED signals the necessity to water a plant; Very low current consumption3V powered circuit __ Contact: Flavio Dellepiane, fladello @ tin.it

Plants Watering Watcher 2 -  IC1D is a CMOS Schmitt trigger oscillator at about 2KHz.  It starts and continues to oscillate with a supply down to 1.24V (the lowest output voltage of my LM317 variable power supply) or less;  IC1A is an inverter;  IC1B is a Schmitt trigger NAND gate.  Its output is low only when both inputs are at, or higher than the upper Schmitt trigger threshold voltage.  With 47 ohms or less between the probes, an input is always low, so the output is always high. __ Contact: IQ Technologies

Precision Low Capacitance Meter -  This circuit was originally designed to measure the volume of fluid inside a medical syringe.  As designed, it produces a zero to 5 volt output, corresponding to a capacitance change of about 10 picofarads . . . Hobby Circuit designed by David Johnson P.E.-December, 2004

Sonarlike method Detects fluid level -  07/19/01 EDN-Design Ideas Figure 1 illustrates a simple, cost-effective method of measuring the height of fluid in a column by using ultrasonic waves.  Two piezoelectric transducers generate and listen to the ultrasonic acoustical wave.  First, the transmitter piezo element receives stimulation from a square wave that lasts three or four cycles__ Circuit Design by Robert LeBoeuf and Eric Masse, National Semiconductor, Salem, NH


Fluid Level Detectors / Monitors


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