Help: RGBW controller circuit

I am looking for help or advice on how to create an LED controller circuit. What I am envisioning is an circuit 1.5" in diameter inserted in a cup with a translucent lid to change colors and go off when rotated. With a 5-10 degree dead spot where the LED’s are off. I would be looking at a few thousand boards. I want the same functionality and form factor as the Everbright board ( without the automation and animation. Just simple turn to turn on and change colors. I would prefer free rotation rather than limited rotation. Being able to rotate as many times as desired but this is not a “must have”.

I wish to make several of these boards for my grandkids and not for any commercial application.



Is this correct, re-stated for my own understanding?

You want a dial-like thing that when rotated changes colors and then at a certain position and for 5-10 degrees turns off?
The dial should be able to free rotate either direction without detent.
Should there be any pattern when the colors come on or random?

I want the colors to change ROYGBIVW as it rotates from off around to off. Progressing through the colors of the rainbow. I do not desire any animation effects, only simple progression of colors as the lids are rotated. This is to be a simple “Lite Brite” toy for my grandchildren. The rest of your understanding is correct.

You want a dial-like thing that when rotated changes colors and then at a certain position and for 5-10 degrees turns off?
The dial should be able to free rotate either direction without detent.

When the circuit is powered on it should show color dependent on the degree of rotation. So if it was set at yellow when the circuit is powered off, it will come back on as yellow when the circuit is re-energized. The color would be location (rotation) dependent.

thank you,


How is this different from the theeverbright display?
Did you ask them for a quote?
How many knobs in x and y?
What is the cost target?
What is the allowed size of the backplate W and H?

Not knowing all the detail my immediate stab at an approach.

Each knob has an integrated Arduino, position detector, and 3 colors led.
One Arduino could be used for the entire array but the wiring including connectors may cost more than individual Arduino’s per knob
A serial I2C interface could be developed that connects all the knobs but that may cost more than integrated Arduino

The Arduino detects knob position and illuminates the correct color
Each knob keeps track of its position at power off
The knobs operate independently and do not interact with each other
The display is not externally programmable

For each x,y postiion:


  • 12VDC power (max knob current x # of knobs)
  • AC power switch
  • AC power light
  • Power wiring to each knob (could use buss bars)


  • Rotary knob connected to the positioning device
    ** Transparent front: balance between transparency, led power and needed 12V supply
    ** Diameter? Larger diameter = more led’s & power
  • Knob mount (to the backing plate). Could screw knobs assy to backplate by the pot/encoder shaft.
  • Backplate holds all the knobs
  • Misc mounting hardware


  • Depending on the size the backplate could be multiple modular sections
  • Could have holes CNC routed
  • Knobs could be 3D printed, cut from acrylic or both
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A rotary encoder, individually-addressable LEDs, and the FastLED library to control them, would be my approach. Individually-addressable means you could control them all reasonably with a single controller.


That would be a very efficient implementation with the additional feature of saving and reloading pictures.
The single knob could acts as a pixel or color selector, switching between these function by a knob push.


Just followed the spec! …:slight_smile:

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I think mentioning the ARRAY has thrown people off.
I am looking for a solution for a standalone circuit.
1.5" in diameter, fully rotatable without detent.
DC input,
Drive LED’s to display graduated colors as the circuit is rotated through 355 degrees
10 degree off index.
Positional, if power is applied while the circuit is rotated 45 degrees the same color will always display.
inexpensive, Ideally I would like to keep the cost to $1-2/circuit.
Circuit will be housed in a plastic cup with rotating lid and translucent lens.

I hope that helps to clarify.


This was part of the original spec. :wink:

@davemcphe I’d like to understand; are you asking for help to learn how to design this, or are you asking for someone to design it for you?

That is the spec what my suggestion started with:

$2.00 per knob will be tough to do…

Looking for help learning to design it, specifically suggestions on components. I am definitely a teach me to fish kind of person.

Thank you,

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I want to thank you all for your help and suggestions. I will further research this out and hopefully post some pics when I get it done.

Again thank you all,


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I know it has been quite a while but I am revisiting this project. What rotary encoder would you recommend. Wiring an 8 bit encoder to take the 5 high bits would give me 32 colors (31 + off). I have realized that the “No animation” actually would make this design harder to do. By using one arduino and controller would simplify things and keep the cost of individual cups down. I am thinking of using the WS2812B LED with FastLED.

Thank you,

Dave McPherson