It's a summer classic: children chase and catch fireflies, watching the curious insects light up in their hands. The harmless activity is often followed by the less harmless placing of the bugs in jars to contain their light- usually leading to their death. To keep the ritual and the insects alive, Michael Ossman of Great Scott Gadgets has created the Firefly Cap, an electronics kit that mimics the light of fireflies, powered by the sun.
The open source hardware kit consists of a small circuit board that fits into the cap of a Mason jar. Placed in a light area (direct sunlight not necessary), it charges during the day, storing energy in a super capacitor, so there's no battery required. A dozen LEDs hang down inside the jar and flicker on and off for a few minutes at night, recreating the flashing lights of fireflies.
Ossman has started a Kickstarter campaign to fund the sale of the kit, but it's not on track to be funded. If you're willing to gather the materials yourself, the instructions are available on Great Scott Gadgets.
It's a neat way to have fun in the summer and add a little light to your night, without the deaths of insects (already in trouble) on your conscience.