I just thought to start a thread on small LED usage: leaded 3mm, 5mm, 10mm, DIP etc. or SMT,
white or colour, special function (RGB, colour shifting). Could discuss uses, small projects, sources,
specs/characteristics and other topics.

I'll start off mentioning a small project of replacing LEDs in small ac-powered night-lights,
which draw less that 1W, typically 1/3W.

I happen to like green and yellow in nightlights but these are not common, usual colours are
white or blue. A few white ones have gone dim over time but otherwise OK, some worth refurbishing.

First is to get the thing apart with minimal or no damage. Damaging ac prongs or anything related
to high voltage, should put that one aside. Also it is common use for a 0.22uF or larger 200v mylar
capacitor in series with the line (as an ac impedance) which can hold a charge for a while, so
be careful. Avoid mods to the high-voltage section.

With one light, the clear cylindrical diffuser (one reason I mod'ed this one) was glued
to the body. Rather than do major damage, I made a fine hacksaw cut around the circumference and
separated it; easily reattached with a bit of super-glue. The rest came apart by removing one screw.

I removed the dim white LED carefully as the small 1-sided PCB pads usually do not tolerate
much heat; replaced`with a green one. Check polarity before installing new one. I found green
brightness was fine without changing the series resistor, despite the difference in forward
voltage (approx. 2v versus 2.5-3v). I would not try to get too much more LED current as it
could overtax the stepdown circuit.

Anyway, I did similar mod on another light with great results. Green light seems very bright
thanks to eye's high sensitivity to it.

Dave