"John A Gallagher" wrote in message
...
|
| I wish to build an "electric eye" type circuit to span about 3 feet. I
have
| been unable to find any schematic except for model railroads which are
only a
| few inches. I have a Radio-Shack pair (emitter ? detector). The detector
| switches a transistor to pick up a small relay, however, I am having
| difficulty getting it to work reliable at 20 inches. I am not using any
| 'modulation' the emitter is on full time. TV / VCR remotes work at 10
feet.

Go to your public library and look at back copies of Popular Electronics or
Radio Electronics for a construction article. Or search the web.

N