Or you destroyed the transistor when experimenting?


... may vey well have destroyed some components (Micro (port pins), transistor(s), LED(s)) E.g. I can see many small LEDs go dead if they get 80mA, likewise if, at any time, a uC port was set up to sink that much (let alone connected to 12V through resitor and LED). My guess is that the "glow on a 1, glow on a zero, is due to a blown uC port.

I have, in the OPs 'experiments' seen no "I verified by the datasheet that this was OK before I did it"

do not get me wrong, I am all for responsible experiments.

Erik