555 timer ic

Water Level Alarm Circuit Diagram

Here’s a basic water level alarm circuit diagram that uses a 555 timer to sound an audible alarm when the water level rises to a certain level. The circuit is relatively easy to use and may be powered by a 3V battery.

An astable multivibrator is wired around IC1 in this circuit (NE 555). The astable multivibrator’s operating frequency will be determined by the capacitor C1, the resistances R1,R2, and the resistance across the probes A&B. The probes will be open if there is no water up to them, therefore the multivibrator will not produce oscillations and the buzzer will not beep.

When water reaches the level of the probes, some current will flow through the water, the circuit will be partially closed, and the IC will begin to produce oscillations at a frequency proportionate to the value of C1,R1,R2 and the resistance of water across the probes. When there is water up to the level of the sensing probes, the buzzer will beep.

Water Level Alarm Schematic Circuit Diagram:



  • A 3V battery can be used to power the circuit.
  • Assemble the circuit on a high-quality PCB or a standard circuit board.
  • Two insulated copper Aluminiun wires can be used to make the probes.
  • Place the probes in the area where you’ll be measuring the level.

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