Zero, one, three, fun.
This device I call my fire control circuit as it uses green LED's,
which of course you expect to produce light when you apply a voltage
to them. Unexpectedly someone found out that if you shine sunlight on
them they produce a current which is used to switch a circuit.
I immediately observed that this makes perfect sense and is an example
of the principle of microscopic reversibility
The washer acts as an umbrella to obscure the sun's rays from any
of the LED's when in perfect alignment.
The circuitry switches 12 volts which powers a 7192:1 gear motor
from Grainger which will align an array of Fresnel lenses to focus on
a 10' long 3" diameter Aluminum pipe threaded on both ends. I can pump
waste vegetable oil through this pipe and capture process heat for
filtration, drying and to drive the chemical reaction to produce biodiesel.