This project demonstrates a way to get “free energy” – the only power source lighting an LED being a weight slowly falling to the ground. The design is relatively inexpensive and has no waste. It has numerous applications, especially in Third World countries that may not have access to any electricity, much less clean power.
Mechanical Engineering Design Project (UMSL JME 410)
Seidel, Emma M.; Rayseldi, Samuel; and Herman, Austin R., "JME 4110 Weight Powered LED" (2016). Washington University / UMSL Mechanical Engineering Design Project JME 4110. 3.