This is a Elektor Magazine Summer edition ideia. I just put bigger caps.
The circuit is very simple: an ultra-bright green LED, two 10-ΜΩ resistors, two 100-nF ceramic capacitors and a push-button switch. When you press the button, there is a clearly visible flash of light. Then you have to wait a while until the circuit is ready for another flash. But where does the energy come from? https://youtu.be/ORy-nOvW4sw?si=1h6wbJVzi5fRgptB