How you can make a water sensor or rain alarm ?
Very simple ; using circuit presented in this schematic you can make a simple water sensor .
The water sensor of it is made by two metal electrodes arranged very close that a drop of water (liquid) will bridge them .
The electrode sensor can be made on a little pcb .If the liquid ( wather ) is very pure you may change the resistor value to 2.2m ohms and if the circuit is give false alarm sensing you may change the value of resistor to 220k . This water sensor (water detector ) it’s use a 555 Cmos timer and one relay which will be close when the bridge between electrodes exist .