The goal is to demonstrate, visually (with a light of some sort) that power is begin generated, albeit very, very small amounts of power. What kind of set up could I use to light up an LED (or any visual indicator).
My power supply is incredibly small; about 0.1 volts and I'm not sure of the current, but consider it low.
I've heard of things such as a "joule thief" that could maybe allow me to light up an LED with very low voltage, but I believe that works by sucking current, which I don't believe I have enough of to do that with this very small power supply. Another option– if my power supply is constant, but very, very small, can I use a capacitor somehow to store the small amount of energy trickling out of my power supply to then make an LED or other indicator light up (even just flash) once every few seconds or every few minutes?
Best Answer
This is going to be very difficult at best. Transistor circuits don't work with just 100 mV power supply voltage. If you really need to run something from this low voltage, the circuit will need some initial external power to get going. This could charge up a cap to a few volts, which could then run a boost converter which would boost the 100 mV up to the few volts to keep itself going. This is of course assuming there is enough power available to not only run the circuit at the higher voltage after conversion losses, but to have enough left over to light up a LED to a noticable level.
Let's say you get the best efficiency LED you can find and that it is bright enough a 500 µA and drops 2 V in the process. That's 1 mW. Without conversion losses and power needed by the circuit, that would mean the 100 mV supply would need to source 10 mA. If your 100 mV supply can source a few 10s of mA, maybe you have a chance, but you'd still need some initial external energy to get the bootstrap process going.