The humble indicator LED

I proposed a talk to the Hackaday Superconference yesterday titled, “Improve your circuit toolbox: Simple designs that will save your next product”.
While I don’t know if the talk will be accepted, I thought it could be a good discussion regardless and thought I could write out some thoughts here. I haven’t been writing much lately and wanted to stretch my muscles again, so why not?
The first circuit on that list will be an indicator LED.
Yep, that simple of a circuit. Allow me to share a diagram:








