Energy & Sustainability Technology
Homebrew solar light

To give his pepper plants some extra light during the winter months, João Silva decided to set up a solar-powered light that would charge during the day, then light a lamp after dark. Rather than simply scavenging a circuit from an old garden lamp, though, he designed his own SolarLamp circuit from scratch. It looks like a fun project, and he has a good explanation of the issues that he ran into when designing a circuit to work at low voltages. As a bonus, he used the open source circuit toolkit gEDA/SPICE/ngspice to design and simulate the circuit. Excellent work!