This is my simplest idea, and if baked I'd love to see links.

Embed two LEDs in opposite directions in the same transparent epoxy, to make it act like a regular lightbulb where polarity does not matter. This could also make it a good low-voltage AC powered light. For novelty purposes, reversing the polarity could cause the LED to glow in different colors.

(I ran into this problem when trying to teach a 3 year old about electricity...I want a light that just turns on without first having to teach about polarity)
-- cowtamer, Dec 21 2010

Bicolor LEDs http://www.google.c...AU&biw=1003&bih=586
Very common [csea, Dec 21 2010]

It's not a "baked" shout, but here is a proposed patent. http://www.freepate...ne.com/7053560.html
[Jinbish, Dec 21 2010]

These are very common [link]. Many have 3 leads, but if you connect the outer ones together, you'll have back-to back red/green or other color LEDs. A suitable current-limiting resistor will still be needed in series.

(When running such a device from 50-60Hz ac, the human visual system turns the alternating red and green to yellow. Borgs may have differing experience.)
-- csea, Dec 21 2010



random, halfbakery