Prototype 1

With the first prototype basically working when the previous blog was written I turned my attention to improving the design of the LED array.  The first prototype was essentially just an LED strip cut into appropriate lengths, fixed to a substrate and then hand soldered into an appropriate configuration.

While this worked fine it took too long to manually form short wires and solder them to the ends of each strip.  Before starting I had realized that manually wiring up dozens of individual LEDs would be more trouble than it was worth so I used a grid spacing that matched the spacing of the LED strips.  Even that simplification though was too tedious to repeat.

Thinking that I might want to share these with a few people I looked for ways to reduce the assembly time. 

Prototype 2

After spending too much time researching options online I selected ready to use, short LED strip connectors.  I thought these would be a good solution because they would only need to be clamped onto the ends of each strip.  So I ordered a bunch and assembled a 2nd prototype.

I used a thin sheet of clear acrylic with an actual size print of the LED strip layout mounted on the back to help with the LED strip placement.  The self adhesive LED strips were affixed to the acrylic sheet and hot glue held the loops of connector cable in place.

This solution may have gone together a little faster but the end result still wasn't satisfactory.  It worked fine too but neither the LED strip adhesive nor the hot glue held on to the acrylic sheet very well.  And the stiff, wide connector wires wouldn't lay flat since they had to make a 180 degree turn from the end of one LED strip to the next.

Prototype 2

Prototype 3

Looking for a better approach I reconsidered an option I had dismissed early on which was having a custom PCB (printed circuit board) made.  I originally ruled out the idea because I had imaged that the cost of a board of that size would be prohibitive.  Revisiting the idea though I realized that an LED array would only require a single sided PCB with a layout similar to the LED strips.  While researching the idea I realized that I could also have the board assembled.  Armed with these options I came up with this design.

I had to find a suitable PCB edge connector and create a layout footprint for it but that didn't take long.  The manufacturing process took a few weeks, most of which was the time it took to do a trial assembly, verification and final assembly.  The end result though worked right out of the box.

Improving the Software

While waiting for the boards to arrive I spent more time refining the software package.  I added a user interface to customize the color wheel through a simple web page with a few sliders that communicates over WiFi with the controller board through an ESP8266 chip.

Combining the HTML and the unfamiliar to me javascript and web sockets with the processor's C code was an interesting learning experience.  I opted for developing a web page for the interface rather than a smart phone app because it seemed to be more generic and universal.

The Debut

The Color Wheel made its public debut at the 2019 Rocky Mountain Pinball Showdown where my Color Wheel equipped Magic City pinball machine won a 2nd place ribbon for Best Lit Game.

Not bad for a 50+ year old electromechanical game up against a bunch of shiny new solid state pinball machines tricked out with hundreds of dollars worth of LED lighting.