Water Level Indicator Alarm Circuit (Mini-Project) using IC ne 555 timer IC

Today we are going to make a project which will detect the preset water level and when water is reached to this level it will generate a sound.


The objective of Water Level Alarm Circuit is to generate a sound with the help of buzzer when a water level in a tank reached to its preset level (Predefined mark).

Components Required:

Following are the required components for making water level alarm circuit:

  1. IC NE555 (Timer IC)
  2. Resistors: R1 = 1K; R2 = 100K;
  3. Capacitor: C1 = 2.2uF (15V)
  4. Buzzer
  5. 3V DC battery

Circuit Diagram:


Description of Water Level Indicator:

Here is the simple water level alarm circuit using 555 timer IC which will produce an audible sound when the water level reaches to its preset level. This circuit uses 3V DC power supply. Therefore this circuit is quite handy to use.

This circuit of water level alarm is based on the astable multivibrator which is wired around IC1 (NE555). The operating frequency of this astable multivibrator depends upon the values of capacitor C1, resistors R1 and R2 and the resistance across probes at A and B. when there is no water upto the level of probes, because of open circuit astable multivibratoe will not produce any oscillations hence the circuit will not produce sound. When the water reaches to the level of probes, the circuit will be completed and some current flows through the water. Thus astable multivibrator produces oscillations proportional to the values of C, R1, R2 and the resistance across the probes. Now the buzzer will beeps to indicate that the water is reached to its preset level.

Also read:  Air Flow Detector Circuit (Mini-Project)


  •  Probes can be made of two insulated copper or aluminium wires.
  •  Preset level means the level that you want to detect the water in the tank.
  •  Place the probes to preset level, so that it will close the path and generates sound using buzzer.

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Tags: Water level indicator alarm mini project for engineering