light of civilization

This project is to create a device that can run for an extremely long time as much as possible. Even if humankind dies, it can run quietly without being damaged by force and can be noticed. To meet such conditions, a device can only operate in the dark. The light source that lights up has become the best way. LED lights are one of the most important inventions of today's human civilization. They illuminate thousands of households in the dark and can be called the light of today's human civilization. 

Hardware solution: Use a photodiode (silicon photocell) to charge the farad capacitor when there is light. When there is no light, control the PMOS conduction and discharge to power the LED and emit light. 

1. Supercapacitor 5.5V 1F (charge and discharge about 10,000 to 500,000 times) 

2. Try to use red and green LEDs with low forward voltage drop for LED lights so that they can work at a lower voltage (around 2V).

3. The photodiode makes a single lamp bead work in photovoltaic mode. It can output about 0.3V/3uA under room light and about 0.5V/500uA under strong direct light. 8 series connections charge the capacitor through one-way conduction of the diode.

Finally, the entire equipment is sealed with glue to prevent the external environment from damaging and corroding the equipment to achieve a long working life.

May you live a long life, my friend. I hope you will not be sent away by this lamp.