I stumbled across the page looking for comparator circuit.....
That's what I'd call "right down to the bare metal".
Or for a little neater job,
from Si.
Tom_J
I think that this is a case of too much free time with nothing better to do. I remember having to model a triple nickle in school with discretes... Still a monstrous waste of time.. IMO there isn't a lot except the output drive (100 mA) that can't be done better with a Tiny13.
Doc
Or someone just wanted to try for the challenge. Why turn a lamp on a lathe? What a monstrous waste of time.