Posted on Feb 13, 2013

Although many circuits use the varying-capacitance method for checking liquid levels, this simple resistive circuit is much easier to construct. Even a tank of a liquid, such as water, has sufficient conductive salts in solution for this method to work. The probe uses a metal rod that supports 10 insulated wires, which have stripped ends pointing down. As the level of liquid rises, resistors Rl through Rl0 are successively brought into circuit, each drawing an extra 10 p.A through the meter. Shunt resistors Rll and R13 calibrate the meter for a full-scale reading when the tank is full.

Click here to download the full size of the above Circuit.

Resistor R12 limits the current through the meter. If tank isn"t rectangular-ie, if the volume of the liquid it contains isn"t directly proportional to the liquid"s depth-space the resistors accordingly or use a nonlinear progression of resistor values and retain constant resistor spacing.

Leave Comment

characters left:

New Circuits



Popular Circuits

100W Audio Amplifier
Guitar Reverb Effect
Hi-Fi stereo Preamplifier with tone controls
Feedback oscillator
On Indicator
Head phone amplifier circuit
electronic door buzzer circuit schematic
Designing Robust and Fault-Tolerant Motion-Control Feedback Systems
Audio remote control switch schematic