Parts List

C1-C3: .1F, 5.5V
C4: 100uf (3 33uf caps in my flasher)
C5: 6.8uf
R1,R3: 100K
R2: 100 ohms
Q1: PNP transistor
Q2: NPN transistor
D1,D2: 1N4148 or equiv. diode LED: super-high brightness red LED
L1: 100uh or so inductor
Cell: 4-element glass solar cell from calculator


Here is a neat little circuit that I really enjoy. It is nothing more than a solar-powered LED flasher. It is enclosed in a clear plastic block of plastic that keeps it water-proof and isolates it from the environment. During the day or when my light is on, the solar cells charge up the .1F caps, storing energy. During the night or other times or darkness, the stored energy flashes a red LED, every second or two. The caps can store enough energy to make the LED flash for about 20 hours. I made and encased this silly circuit over 5 years ago, and it is *still* working as good as it was the day I made it.

You can see the solar cell and the leadframe from the LED (and if you look closely, the LED lens is visible) as well as the tops of the three "Supercaps".

The rest of the circuit is visible; all SMD was used to make it as small as possible. The solar cell is glued to the back of the small square of perfboard used. I wired some of it up using magnet wire to save even more space.. some of this is visible.