I think a vision most builders have for their completed panels are having them all lit up with loads of various LEDs and indicators. I too have the same vision. However one thing to keep in mind is that some LEDs can be quite bright, especially the blue and white LEDs.(I’ll come back to this)

Now if you have even a little electronics knowledge you should know that you cant have an LED hooked directly hooked up to the 5 or 3.3V power supply of your arduino. You NEED a resistor to limit current and prevent killing your precious diodes. For standard 5mm LEDs a resistor somewhere in the range of 220 and 330 ohms is a good place to start. Obviously the more ohms the dimmer the light will become.

The LEDs I bulk ordered from china are quite bright especially when it comes to the Blue and White varieties. Having a bunch lit up shining in your face while your trying to play the game isn’t optimal. So I figured before I bulk order a bunch of resistors I should test each color LED and find a resistor value that gives each color an even and comfortable brightness. At first I thought the best way to do this would be to use a potentiometer in series with the LED to tune the brightness to a level I was happy with then use a multi-meter to measure the resulting resistance value. This is a perfectly acceptable way to do this but then I came across a method I liked a little better. (and is a lot more precise and reliable)

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A “programmable” resistor! This board has 63 surface mount resistors on one side and 7 sets of headers on the other. Using the provided pin jumpers you can set the board to have ANY resistance value from 0 to 9,999,999 ohms (almost 10 Megaohms) I picked this up cheap off AliExpress for $2.98 CDN plus $4.90 CDN shipping. It will surely be a handy addition to my toolbox and i’m sure you’ll be seeing me use it down the road.

Ignore the misprints on the board, the max value is NOT 1000 Megaohms as the silkscreen implies. :p