We had some Automation Direct parts left over from a system integration job: an LED stacklight, a 18mm capacitive sensor, and several others.  I got bored one day and put some of them together just for fun.   With a couple of tiny 12 volt batteries inside, this stack light will now illuminate when ever it’s placed on a metal surface.  We’ve had lots of fun placing it on various surfaces around the office.  People assume we’ve drilled a hole in their credenza or other office furniture to run the wiring.  Then they pick it up, and the lights go out.

Funny to us geeks anyway…

The sensor is mounted in the base of the stacklight, pointing down of course.  We put a small radio shack switch under there also, to turn the unit on and off.

These 12 volt batteries are useful.  Shorter than AAAs, but about the same diameter, they’re intended for garage door remotes, and other “security” devices.  They don’t last very long in the stacklight, but they do fit in the base - that was the main criteria.   We used a couple of “n-cell” battery holders (also from radio shack) to house these, they aren’t n-cell size but they fit pretty well.

So inside the stacklight base, you can see the back of the sensor, the batteries & holders, and the rat’s nest of wire (yeah, it’s ugly, but it works).

Now maybe we’ll add a blink pattern or some other.  Anybody got ideas for improvments?

Filed under: Projects