I was testing some leds with a variable voltage supply I had 12 leds in series I turned the supply up till they all came on.
Looked great I turned off the supply. I then came back to see how much I could go I turn on the supply and a big bang I now have a scar from
one of the leds. I must hit the pot on the supply..
I gave up on the voltage idea for leds and went with current controlled supply.