Hello I planned a light sensitive one pulse activated switch to know when water tank is completely filled and to turn the water pump off using a relay until I reset the circuit using its N/C Switch.


NOTE: There is an external circuit to detect if water starts to overflow through overflow pipe and turns a Red LED(http://www.kynix.com/Product/Cate/545.html) on to make this light sensor circuit detect it.


Light sensitive part is working fine, but the problem is when I supply power to the circuit, Relay 2(RL 2) I mentioned in this circuit diagram keeps turning on and off continuously and I hear its extremely fast continuous switching sound like a damaged speaker. Relay 2(RL 2) will die if it turns on and off in such speed. (The purpose of RL 2 here is giving continuous current to the RL 1 to act as a one pulse activated switch.) I want to keep Relay 1(RL 1) turned on even light turns off and only to be turned off when I reset the circuit.


Here is the circuit diagram:

What changes can I do for this circuit to keep the Relay 1 (which activates by a light falling on LDR) on until I reset circuit using N/C Push Switch?


Thanks in Advance.

Krow is on to it. RL2 seems to be 'shorting' itself when the contacts close (relay operates) so releases until the contacts open and then cycles again.It is also putting 12v hard across that diode which may be stressed?