Michael Ireland finished building the Kit IR Light Fence / Door Minder DIY Kit (kit 130 from kitsrus.com) and putting the two parts in a box and powering them with a 9V battery. He took the output relay and connected that to the mote, which is programmed with the same software we are using for the pucks. When the light signal is broken or reconnected, the mote sends out an RF beacon. There is a quarter at the bottom for a sense of scale.
We’ve talked shrinking this down and combining the two parts into one box and using a reflector on the other side. The circuit draws about 24mA @ 9V, so it aught to last on the order of 20 hours.
Not the same thing, but I hacked an $8 motion detector/LED night-light (which uses a pyroelectric sensor) to turn on a mote. Probably the cheapest way to add motion detection sensing to a mote.
Comment by tedherman — December 7, 2009 @ 4:54 pm