I've been watching a YouTube video and wondered how the circuit lit an LED just by heating up a coil with a lighter.
Here's the circuit diagram. "Copper wire" is the coil I'm referring to.
Here's the photo of the coil being heated and an LED lit.
My guess is,
- the coil was heated up.
- electrons in the coil were released by thermionic emission, creating a positive electric potential in the coil.
- a very tiny current flew from the coil to one of the transistors.
- the current was amplified by the two transistors and drove the LED.
But I'm not sure about the thermionic emission. The most famous example would be a vacuum tube but that is vacuum. This one is in the atmosphere.
Am I correct? If not, how does this work?