Schematics > Security and other sensors and detectors > Rain Alarm
Rain Alarm
This circuit gives out an alarm when its sensor is wetted by water.
A 555 astable multivibrator is used here which gives a tone of about 1kHz upon
detecting water.
The sensor when wetted by water completes the circuit and makes the 555
oscillate at about 1kHz.
The sensor is also shown in the circuit diagram.
It has to placed making an angle of about 30 - 45 degrees to the ground. This
makes the rain water to flow through it to the ground and prevents the alarm
from going on due to the stored water on the sensor.
The metal used to make the sensor has to be aluminium and not copper. This is
because copper forms a blue oxide on its layer on prolonged exposure to moisture
and has to be cleaned regularly.
The aluminium foils may be secured to the wooden / plastic board via epoxy
adhesive or small screws.
The contact X and Y from the sensor may be obtained by small crocodile clips or
you may use screws.
Title: Rain Alarm
Source: www.electronic-circuits-diagrams.com
Published on: 2005-02-01
Reads: 1170
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