CHAPTER 10 ■ LEDS
Because one wire is dedicated to each of the two LED colors, they can be enabled at the same time. This
permits three colors (one on, the other on, or both on) plus “off.”
Full Color
Full-color LEDs are the Holy Grail! These RGB LEDs contain red, green, and blue dies within the same LED.
By electrically adjusting the brightness of each die, you can mix the primary colors together to create almost
any color.
RGB LEDs have four leads (see Figure 10-12): one lead for red, one lead for green, one lead for blue, and
one lead to share. That makes them more complicated to hook up.
In the last ten years, the cost of an RGB LED has dropped to 1/10th the price. You can find them at almost
every electronics reseller. For example, SparkFun Electronics sells a 5 mm full color LED for $1.95 (clear lens
#COM-00105, diffused lens #COM-09264).
Testing an LED
The most obvious way to test an LED is to connect it to a circuit (next chapter) and see if it lights up. However,
if your multimeter has a diode test function, you can safely test LEDs and learn a few things about them.
Figure 10-12. Red, green, and blue in a single LED can make almost any color