Fireflies in a jar are a wonderful childhood memory for many of us. Not surprisingly, it's one of the things that Tom Padula missed when he moved from the Midwest to Silicon Valley nearly two decades ago.

So in the spirit of Silicon Valley, Padula decided to create electronic fireflies: lightweight, inexpensive, solar-powered bugs. At night, the fireflies flash a light on and off for about two hours, then switch off to recharge in the next day’s sunlight.

"I built about 20 and hung them in the backyard, on branches and bushes," says Padula. "Bliss."

About the size of a quarter, the electronic fireflies have a rechargeable battery pack. The batteries are charged each day by six tiny solar cells. At dusk, they come alive with a fading on-and-off pattern.

"The slightest breeze moves them around, and the motion combined with the light is mesmerizing," says Padula, who will be selling his digital lightning bugs for $10 apiece at the fifth annual Maker Faire Bay Area, which will be held this coming Saturday and Sunday, May 22 and 23, in San Mateo, California. The annual event, put on by O'Reilly Media, is a celebration of DIY culture, arts and crafts, and will likely draw more than 70,000 attendees, organizers say.

Padula's fireflies weigh 0.2 ounces (7 grams) and are attached to an 18-inch monofilament line. Six solar panels charge NiMH batteries, and a microcontroller drives the LED. The units are dipped in epoxy for weather resistance.

"All the real work happens in the code, from determining ambient light level, to controlling the LED intensity and keeping track of how long the pattern has been active so as to turn off after two hours, like real fireflies do," says Padula.

Originally, Padula assembled each device by hand but now contracts it to a shop in Nevada.

Padula says he initially created the electronic fireflies for his enjoyment but after encouragement from friends and family, he hopes to make a business out of it.

See below for a closer look at the firefly.

Photos: Leslie Dunscomb