The Red/Green LED Guide

The Red/Green LED is handy little component that allows two colors (red and green) in a single LED while only having two pins (cathode and anode).  The color of the LED depends on the polarity of the connection only allowing one color at a time.  Similar LED's that provide two or even three colors usually have three or four pins allowing for a wide range of mixed colors.  One would think having two pins is a disadvantage; not so.  This LED can easily be applied to a circuit to visually indicate polarity direction.  Or in my case it can save me an extra i/o pin on a forthcoming arduino project.

I've read mixed reviews from those who have purchased this particular LED.  Most of the negative reviews comes from those who aren't really sure how to use this LED due to it's unique design.  Most of the positive reviews comes from those who have used it as a line status indicator. 

Step 1: Straight out of the package

The first thing you'll notice is that this looks like any other common LED, but with a white diffused lens.  It has a short negative lead (cathode), and a long positive lead (anode).  On the inside there are two LED's in parallel to each other, one forward and one reverse.  The package included with the LED from radio shack provides a similar looking schematic to the one I provided above.

Comments

[amandaghassaei]

interesting, what kind of projects ave you used these in?

[Spaceman Spiff]

I'm using this in a game I'm making. The game begins when the light changes from red to green.