Another pic from the past – Apr 2009. The 10 Farad supercapacitor powers the flasher brightly for 1 hour and dims for another 3 hours.
The circuit consists of an astable multivibrator with unequal resistors to make it put out a short pulse every second or so. This is the three transistors to the left of the power wires. To the right of the power wires is a Joule Thief that has its 1k resistor fed by the pulses from the astable multivibrator, gating the JT on and off. The output from the JT is rectified and filtered before it gets to the LED. The extra holes in the board are for different configurations.