I wanted to upgrade him with a solar engine, and I decided on the FRED solar engine. Originally, I was going to build the FLED solar engine, but it is so inefficent it drove my perfectionist side insane. Sooooo, I ended up spending half an hour getting this circuit to work, and I suceeded in getting it to pulse in direct sunlight and under an incandescent desk lamp. The FLED couldn't even pulse with the light bulb literally on top of the solar cell!
I included a video of it pulsing wherever videos I embed in my posts go/are.
Statistics:
one 1F capacitor
two 1000 μF capacitors
one 0.47 μF capacitor
three 1K resistors
three 10K resistors
one red flashing LED
one 4.0 V, 2-3 mA solar cell
one 2N3904 transistor
one 2N3906 transistor
Some images of the circuit:
https://www.youtube.com/watch?v=mZyrP4wdjvc