This is what I use for the sensor:

http://www.amazon.com/SECO-LARM-SM-216Q-Wide-Magnetic-Contact/dp/B002ZOQ0RQ

Bob

On Tuesday, October 11, 2011 11:16 PM, "V G"  wrote:
> Hi all,
>=20
> I want to make a simple, cheap, quick, reliable (no one dare say you can
> only pick only x) garage door open detector that will light up an LED in
> the
> house/beep a speaker if the garage door is open. I know all it takes is a
> mechanical switch, but I'd rather not use any moving parts. I'm thinking
> a
> very bright infrared LED and IR transistor with a piece of foil mounted
> on
> the inside of the garage door. If the door is closed, a series of LED
> pulses
> will hit the aluminum foil reflector and bounce back to the IR transistor
> and signal the device that the door is closed. Will this work? I've never
> done any IR work, so I don't really know what power LED is required, what
> the distances are, etc.
>=20
> As for the micro controller unit, I can make it wireless and signal the
> indoor unit via something like this
> http://www.sparkfun.com/products/10534but I'd have to impliment
> encryption on the micro controller itself. It
> would also interfere with other units in the same band, which is very
> very
> undesirable. How hard is it to implement simple encryption?
>=20
> Xbee is cool, but it will add $40 at least to the cost of the project.
>=20
> Any other ideas?

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