How to design an infra-red circuit to detect small obstacle

[anwar]

Hi,
I am trying to figure out how to design a simple infra-red circuit
so that it can detect any small obstacle placed/passed in between
infra-red receiver/transmitter. I want a light to turn on or whatever
else to happen when this obstacle is detected.

The distance between receiver/transmitter will be maximum 2 feet and
minimum 6 inch.

Thanks,
Anwar
http://www.bluehawk.biz
http://www.bluemela.com

 

[anwar]

Larry,
- I do need a narrom detection indeed. So if I have a 2 feet
separation and there is a narrow beam where if someone place a finger
or pass his finger thru the narrow beam quickly it should detect that.

- As per level of gain- I need to make a sound of a certain frequency
when the obstacle is detected.

So, if you can please provide me details on how to make a circuit like
that it will be wonderful.

Thanks,
Anwar
http://www.bluehawk.biz
http://www.bluemela.com