what is the name of the circuit used for the purpose, whenever there is an obstruction between a light emitter and a light reciever the path will be broken and this will be indicated by an indicator and when there is no obstruction between light emitter and reciever the path will be maintained .
what type of circuit is this ? what can be used as light emitter and reciever ? any alternate circuit for this for the same ?

 

sorry for posting this i got the circuit

 

sorry for posting this i got the circuit

Given you have the circuit, would you like me to lock the thread?

Dave

 

ya sure ,once again i'm sorry for posting it

 

No problems. Locked at the authors request.

Dave