Little Leonid Lights

These little trail lights are named for Leonid Andreev, who originated the idea of making artwork out of lighting trails at regional camping events. To make one, the main component is a battery-ready LED module -- I have about forty color changing LED modules from Acolyte, and I hear there are other sources and colors. Be aware that a regular LED will NOT work in this way -- it needs a resistor, at least, to light up without frying the battery or itself.

In addition to the LED module, each light needs two 2032 lithium coin cells (mail order is much cheaper than buying them in a drugstore), one small binder clip (available at most stationery stores), and a small baby food jar (without label). Optionally, electrical tape for insulation, and a small piece of stiff paper to turn it off (old business card stock is just about right). Click on the thumbnails below for the full size pictures.

The only nonobvious thing is the polarity of the LED module -- examine it carefully and notice the differences between two leads. The crimped shorter lead, on the flat side of the module, is negative, and goes to the smaller side of the battery. The straight longer lead, on the round side of the module, is positive, and goes to the bigger side of the battery. Here "battery" actually means the stack of two coin cells.

Also be aware of the "short point" where the negative lead crosses the edge of the cell, as shown in the sketch. It's possible for the negative lead to short the positive and negative ends of the cell, right at that corner. If that happens, the cell will overheat and vent electrolyte, which is a vile spooge that you do not want to deal with. Bend the leads so as to avoid a short, and there should be no problem.

In the upper right corner of the pictures is an assembled light. I use a piece of electrical tape to line the binder clip and ensure that it doesn't short the battery. The binder clip is enameled, which should insulate by itself, and I've tried a few without the tape for short periods, and they seemed to work fine. But I worry that the enamel could get scratched and short the battery, so I usually use the tape.

There is no power switch and it will light up as soon as it's assembled. It can be turned off by slipping a piece of stiff paper in between the two cells (as shown in the lower right corner of the pictures). With a little practice, it's not hard to open the clip just a little, so as to slip the paper in or out, while still holding the assembly together. I usually hold it against my leg, with one hand to open the clip and the other to move the paper, and miscellaneous fingers holding the assembly together. When the light is on, keep the paper in the jar along with the light, so it'll be handy to turn the light off again.

Battery life is usually good for three or four nights, if the lights are turned off during the day. The first night will be noticably brightest, then the next two or three nights will be moderate, then maybe another night or two dimming out.

I've also tried powering these LED modules with a stack of three AAA alkaline cells, in a small holder with a power switch. Although the power switch is convenient, battery life is noticably shorter with alkaline cells than with lithium cells, and the alkalines are much bulkier and heavier, and no cheaper when mail ordered in bulk, so I don't recommend them.

This page maintained by Wil Howitt
Last updated 24 February 2008