"Andrew McKay" wrote
| As I remarked in an earlier message, I now have a fully working
| automatic garage door. However one problem is that if I don't remember
| to park the Freelander forward then I'm going to have an expensive
| repair job to look forward to, as the canopy door extension bar sticks
| out several inches, and will clobber the rear of the Freelander.
| I need to have some sort of proximity detector which will either
| prevent the door from closing, or alternatively beep at me or flash a
| light if the car isn't far enough forward in the garage.

An infra-red beam break detector positioned the requisite distance/height
from the garage door sounds the sort of thing. Maplin.co.uk BZ64U or p557 in
the Catalogue for GBP 25. 12-20Vdc supply, reed relay normally-closed might
do the job.

Owain