Last year around this time I started a new project to challenge my abilities in hardware design and software programming.  Truth be told, I have been thinking about the project for a number of years, but never really had the time to work on it.

The idea was to outfit a Faller Power Tower ride with LEDs lining the tower.  There are a number of videos on YouTube with something similar, but none of the videos really show the mechanisms up close or provide any details on how they accomplished it.  I’ve always been fascinated with the shear number of LEDs on some of the videos and prospect of controlling them.  So, I set out researching the control mechanism, mounting techniques, and assembly ideas.

I guess I should forewarn anyone who might read this, I had not fully thought through size and scope of the project.  Nor the slippery slope I was about to slide down.  In the end, the first phase of the project yielded approximately 1000 LEDs lining the sides of the power tower, and Phase 2 led to approximately 219 more LEDs for the mast, and Phase 3 will lead to another 219 for a main sign.

At this point any sane person might think I’m crazy or simply bored.  Neither.  Just the average maker looking for a challenge.

So, on with the description, pictures, and maybe a video or two.


To drive a lot of LEDs, you need a lot of output pins and a lot of current.  It is simply not feasible to control each (normal) LED individually.  Building a circuit with over 700 outputs would be very problematic, not to mention wiring 700+ wires would be, well, crazy.  Likewise, controlling the intensity of each LED with any level of granularity leads to all sorts of other complications.

I knew multiplexing would be in the future, so researched all the popular mechanisms and prototyped the more popular ones: Matrix Multiplexing and Charlieplexing.  Then I investigated ways to control the intensity, which included Pulse Width Modulation (PWM), Binary Code Modulation (BCM), and a couple other techniques.

Multiplexing and controlling many LEDs with as few pins as possible is well plowed ground.    The Internet is full of ideas, circuits, and code.  After much, much research, I decided a traditional matrix was the best solution.


The power tower is approximately 25 inches tall.  I felt it would look very odd with only one side lit so I decided I wanted to have LEDs on all 4 sides.  I also determined a single strip of LEDs per side would look very odd.  So I settled on a column of LEDs on each corner of the tower, working out to 8 strips of LEDs, approximately 25″ long.

I designed and manufactured some LED strips for my research with multiplexing (shown below).  The strips are each 3.625″ long, with 6 groups of 3 LEDs each, totaling 18 LEDs per strip.  That means 6 outputs per strip and a common anthode.

LED Strip Schematic v1.0

LED Strip Schematic v1.0

LED Strip PCB v1.0

LED Strip PCB v1.0

Here’s where the real world enters and I start doing the math.  25″/3.625″ = 6.89 strips; I’ll round down and make it 6.  8 columns x 6 strips/column = 48 strips.  18 LEDs/strip = 864 LEDs.  Holy crap.

Ok, so despite the Internet being full of a lot of useful information, nothing I came across led to a matrix of 864 LEDs. Further complicating the situation, my LEDs were grouped in 3’s and powered by 12 volts instead of the more “traditional” 5 volts.  I’ll get to why that’s important later.

I determined none of the “out of the box” solutions would work for me.  I needed more drivers than the solutions provided, or I required more current than the solution offered.

In Part 2, we will discuss the design and the build.