Water Sensor Circuit Diagram using IC 555

This is a water sensor /rain alarm circuit diagram; it can be used on motorcycle, car or other device that we want to protect from water, rain.
This is a simple water sensor/rain alarm circuit that makes an alarm when water/rain falls on its sensor. This circuit is based on NE555/LM555 IC and two transistors (Q1&Q2). For  transistor Q1- BC547 or BC107 and for Q2-  2N825,BC548 or BC168 can be used in the circuit. This rain detector circuit can be supplied from voltage source of +9V-12V DC. The resistor 470K ohm is a POT/Variable resistor; it is used to adjust the sensitivity of water/rain sensor. Use a 8 ohm,0.5w-1W  speaker to hearing  better alarm. Less than 8 ohm speaker could be harmful for the IC 555.

Circuit Diagram of Water Sensor

Fig-1: Water Sensor/Rain alarm circuit diagram

Water sensor PCB layout:

Fig-2: PCB layout of water sensor
We can make the water sensor as shown in the image (Fig-2) using aluminum conductor like a naked wire . Here can be used other conductor but we suggesting to use aluminum.


  1. Can a relay be used in place of the speaker and, if so, what voltage?
    I had trouble finding a 0.01uF polarized capacitor so tried replacing it with a non-porarized capacitor. Dunno if that's the problem, but, so far, it hasn't worked.

  2. Of course you can but with a required interface for relay.
    also there is not a big problem with non-polarized capacitor(0.01uF), you can use it. all the best...

  3. Nice Circuit.....
    Thanks buddy......

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