This shows how much variance there might be to the resistor's Ohm value. If our example resistor ended in gold (orange, white, black, gold), its 39 Ohms value could be five percent higher or lower.

Use a wire to connect the minus side of the LED to the ground port on the Arduino. Optional step: Add a 220 Ohm resistor to prevent the LED from overheating. Connect as illustrated in the picture.

The color code was very useful in quickly identifying a resistor’s value. It’s simple, and straight forward. But you have to make a little room in your brain to remember this stuff.

Well, there’s a new time-telling game in town, and as far as we’re concerned it’s one of the best ones yet: resistor color codes. The Ohm Clock is, as you may have guessed, a giant model of ...