Simple Rain Detector Alarm
This rain detector alarm circuit project is an very simple circuit , that will start an audio warning , if the liquid is present on the sense pad . This rain detector alarm circuit diagram is based on two transistors BC547 and BC557 . When the sense pads conducts , Tr1 and Tr2 will generate a pitch sound .
This circuit needs a 12 volts power supply circuit and the speaker needs to have a 32 ohms . The sense pad can be constructed on a small piece of printed circuit board .
Note : Sensor automatically goes high in certain seconds in regular period for simuation purpose, In realtime sensor gives high when rain drop detected.