Dark Sensor Circuit stops responding after few seconds.....

[Abhinandan Aggarwal]

I have made a Dark Sensor circuit and My Circuit stops responding to the light change after some time, i cant find the error pls help....I have also attached the schematic and board layout

 

[esp1]

hi,
How long a period is 'after some time'.?

How is the sensor circuit powered.?

E

 

[Vbase]

I have made a Dark Sensor circuit and My Circuit stops responding to the light change after some time, i cant find the error pls help....I have also attached the schematic and board layout

This circuit does not flip from on to off or from off to on, the relay pulls when the transistor current builds up when it gets darker. If the process is long the transistor can get too hot and burns.
Look for signs of overheat on T2.
To correct the problem you can replace the transistor to a bigger case TO220.
If you want a perfect solution change the circuit to a flip-flop.

 

[Abhinandan Aggarwal]

The approximate time period is 1 or 2 minutes and the sensor circuit is powered by power supply of 12v from a transformer using a bridge rectifier....

 

[kam1787]

How current is going thru the LDR?