8:09 AM
Fera Har-q
This is a simple circuit that can be used to detect rain. It will give a loud beep when the first drop of rail falls on the sensor. So it useful to detect rain where sun drying is carried out.Op-Amp IC 741 is designed as a voltage comparator. Its inverting input pin2 receives half supply voltage (4.5V) through the potential divider R1 and R2. Its non-inverting input pin 3 is connected to touch pads and variable resistor VR1. Output of the comparator becomes high only when its pin3 gets a higher voltage than pin2. Normally pin 3 is low because it is not getting current from the positive supply. So output remains low. This inhibits transistor...
