Few years back two youngsters recorded a video on how to create a Rain Alarm yourself (Hindi). You can watch this video by clicking on this link: http://youtu.be/GnkMgYbjaao That video goes popular on youtube and people started asking question on working of the circuit. These two kids were not the right person to answer this question. So we request Mr. Raj Kumar Thenua to answer this question by recording a video.
In this video Mr. Raj Kumar Thenua (Sr. Lecturer at Anand Engineering College, Agra, India) demonstrate how does rain alarm circuit works.
We hope that this video will be helpful to you.