Electronics help & Light beam sensors

["psghome2002" <psghome@xxxxxxx>]

I'm trying to make up a combined parking sensor and garage door 
safety switch to be fitted to the inside of the door frame and 
looking across the opening (double garage width). I imagine the 
output to be linked to HomeVision which, in turn, will allow my 
Comfort system to close the door (or not) depending on any number of 
factors I choose to program. I'll also have a couple of high 
intensity LEDs (red and green) mounted in a box on the far end of 
the garage wall so I can tell when the cars are far enough in to 
close the door (or if there's an obstruction).

The signalling, interface to the electric garge door and LED's are 
pretty simple and not a problem but the light beam sensor is. I 
bought one of those Velleman kit form beam break sensors that uses 
two IR LED's (transmit) and a single receive LED. Unfortunately the 
range is about half of what I need. I'm also wondering if IR beam is 
the best technology to use (poss interference from remotes, sunlight 
etc)?

The transmit circuit looks pretty simple with just a few resistors, 
capacitors and three transistors. Might it be possible to boost the 
transmit power enough using this circuit, or should I look for 
another sensor - I've had a look at what RS offer but most of them 
are pretty expensive and only a few offer the range I need.

Any thoughts / suggestions?

Thanks,

Paul.

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