Picture of Making an RGB LED Colour Slider using Bare Paint

In this tutorial we will build a physical RGB (red, green, blue) LED (light emitting diode) colour mixer using Bare Conductive Paint. Each RGB LED has three internal light emitting diodes (LEDs) for each of the colours - red, green and blue. Further there is a lead to connect and control each of these internal diodes. Thus you can mix these three and get a whole range of new colours. The diagram below shows what one would commonly find inside a RGB LED.

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Step 1: RGB LED Internal Diagram

Picture of RGB LED Internal Diagram
You can see that pin 2 is the three internal LEDs negative lead or cathode and 1, 3 and 4 are each of their respective positive leads or anodes. We are going to physically control the RGB LED by making Bare Paint Potentiometers for each of its positive leads instead of using static resistors. Thus by altering the resistance we will ultimately change the current flowing into each diode and affect its brightness. This is a fairly crude way to control LEDs. There is a more elegant way to do this using an Arduino and PWM (pulse width modulation). We will cover this in another tutorial.

Step 2: Components

Picture of Components
The image below shows a RGB LED with a common cathode. This simply means that the 3 internal LED's share a common lead and this lead should be connected to ground. Ground is a name electronically minded folk use as the reference point that all the other voltages are measured from, or a common return path for electric current. In our circuit ground simply means the negative terminal on the 9V battery.

Step 3: What you will need:

Picture of What you will need:
What you will need for this tutorial:

Bare Paint
Paint Brush
RGB LED (common anode) - if using common cathode please modify circuit diagram
Jumper Wires
Paperclip Wires and Paperbinder Wires (use stranded wire, solder and basic stationary components to make these highly useful connectors)
Battery and Battery Clip

9V Batteries - Jameco
Battery Clip -  Jameco
Stranded Wire -  Jameco
Soldering Kit -  Jameco
Paper clips - Any stationary shop
Resistors UK:  Sparkfun
Breadboard -  Sparkfun
RGB LED -  Sparkfun

So simple and a great use for Bare paint. I look forward to doing this!