Hello, I made this simple circuit, and understand its basic functioning but, there is something left. I don't know and haven't been able to understand what is the zener diode doing there, I made the prohect and it didn't work, I put away the zener and it's working, maybe it was a mistake to put it there or maybe not. What is the idea of the zener in the circuit?
I would like to use it with HB LED(s) maybe I need a driver, I would like you to give me a hand there too, 'cause I have never used them.