LED Poles

2024-04-14 | By bekathwia

License: See Original Project

LED Poles

Introduction

Here’s how I made four LED poles for a recent art performance here in New York City.

The project brief, as it was pitched to me, was to create four tall uprights for the corners of an eight-foot by eight-foot raft. These LED poles needed to be quick to deploy and start up the animation on their own after a five-minute countdown timer. Just in case anything were to fail, the show must go on without human intervention, so they needed to have as much redundancy as possible built into the design.

So, I designed a set of four independent circuits, one on each pole, that contained a strip of pixels that would go up the pole and then over to the top of its neighbor, with some slack to drape in between the uprights. This design ended up looking like an LED huppah.

Oh, and I had one week before the show to build everything, so this is a speed project.

Supplies needed for this project (also available as a DigiKey wishlist):

4x reels of WS2812b LED strip
4x ½” electrical conduit
4x USB batteries at least 5000mAh capacity
4x USB cables
4x microcontrollers with 5V operating voltage such as Pro Trinket
4x capacitors, each 500uF-1000uF 6.3V+
4x 300-500 ohm resistors
Electrical tape
Zip ties
Wire
Soldering tools and supplies
- Soldering iron DK FX888D-23BY-ND
- Solder DK #2260-WBNCC633731-2OZ-ND
- Wire strippers DK #1691-1281-ND
- Flush cutters DK #1691-1037-ND
- Pliers DK #1691-1422-ND or tweezers DK #1597-1536-ND
- Eye protection DK #3M158306-ND
- Workholding tool (often called a third hand) DK #1568-1077-ND
- Multimeter DK #DM220-ND
- Heat shrink tubing DK #1528-4559-ND
- Heat gun (or a lighter) DK #1568-1602-ND
- Solder wick DK #315-SOLDERWICK2.0-ND or a desoldering pump DK #243-1183-ND for fixing mistakes
Paracord

LED Poles

Building the Circuits

LED Poles

View/modify this circuit on Tinkercad

Each circuit consists of a whole reel of RGB WS2812b NeoPixel strip (along with its recommended capacitor and data line resistor), a microcontroller to drive the pixels, and a USB battery pack.

LED Poles

This project was short notice, so I used whatever Arduino-compatible boards I had around the workshop already. Even though you normally wouldn’t solder to a board with female headers like the Adafruit Metro, it’s still doable.

LED Poles

It’s strongly recommended to add an extra capacitor when doing projects with long runs of addressable LEDs to help smooth out the power spikes. It matters more for circuits connected to AC adapters, but it also can’t hurt, and these strips come with extra power and ground wires that are perfect for just this purpose.

Likewise with the resistor hooked up between the Arduino’s output pin and the data input on the first pixel– even if there is one already, doubling up can’t hurt.

LED Poles

Testing the Pixels

I loaded up the NeoPixel strandtest program on each of my four circuits, adjusting the sample code to increase the number of LEDs in the strand and decrease the brightness so the total power draw stays within the limits of the battery pack.

Now that the circuits were assembled and tested, it’s time to switch focus to the physical structure.

LED Poles

Strip Connectors

At the output end of the strip, I needed to create a leash for attaching to the neighboring pole, so I took an elastic hair tie and zip-tied it to the end of the strip, just below the knuckle that is formed by the silicone end cap. Then I became concerned the elastics wouldn’t be strong enough and installed a redundant piece of paracord in the same way.

LED Poles

Constructing the Poles

I picked up four pieces of electrical conduit at my local big box store, then measured and marked them for cutting down to length. I don’t have a garage or easy outdoor space for this task, so I just used a piece of scrap wood to cut against with my angle grinder fitted with a cutoff wheel. I also cut notches in the ends because I thought they could be used for attaching the ends of the loose LED strips.

I removed the sharp edges on my belt sander and wrapped the top ends in electrical tape, thinking it would buffer the cord from rubbing against the still-sorta-sharp-on-the-inside metal.

LED Poles

Pole Assembly

Next, it was time to affix the circuits to the poles, which I did using zip ties and electrical tape in between the LEDs. I left some bare metal at the bottom for the poles to stick into the holes in the raft. Once I had all four assembled, I stood them upright in my studio to start working on the animation.

LED Poles

Programming and Testing

In the code, the first thing I tackled was the startup delay. I used Arduino’s built-in timer called millis(), which is always equal to the number of milliseconds since the program started running. I can compare this to a variable I define as my startup delay and only proceed with the show when it’s time.

LED Poles

It’s helpful to be able to tell that the circuit is working during this five-minute countdown, so I also wrote a little function to flash the first few LEDs once per second during this time. It will light up one pixel for each minute that is left on the timer, for instance at five minutes, five pixels flash, then four, then three, and so on so you can tell approximately how much time is left before the show will start.

LED Poles

Designing the Animation

Download my Arduino sketch

The whole art piece has a fireworks theme to it, so I programmed an animation with a flame effect, and then some random flashing in the same colors. It’s not exactly the most sophisticated NeoPixel show ever created, but it was finished on time and did its job– I delivered the poles to the group and eagerly awaited the performance.

Performance Time!

It was an anniversary celebration for the Madagascar Institute. You might remember them from the Jet Ponies and chariot races at Maker Faire New York in 2010, or the D ueling Mechanical Bulls I made a video about on my YouTube channel. This anniversary commemorates 25 years since their first event in 1999.

LED Poles

Deployment

From what I could tell from the audience, everything with the deployment of the poles went according to plan. After the performance, the raft materials were reclaimed, and I was able to bring them back to my studio. There wasn’t exactly a huge budget for this project, so reclaiming the salvageable materials will help reduce the overall cost.

LED Poles

Damage report

This project was a rare opportunity for me to test my construction methods against some tough conditions, and I learned some things from inspecting the poles after the show. The most noticeable thing was that zip ties can slip on smooth surfaces, and they did on the batteries. The electrical tape was much better for this purpose, so I’m glad I used both.

LED Poles

Next, it’s the methods by which the pixel strip was broken or damaged. The LEDs affixed to the poles had no issues, but the long tails took some damage along their lengths as well as at the transition from the pole to the free-hanging LED strip.

LED Poles

The silicone sheathing is more stretchy than the pixel strip, so when the whole thing was pulled, the strip inside pulled apart before the silicone was done stretching.

LED Poles

At the tops of the poles, my attempt to soften the strips’ transition by adding a stiff zip tie tail to the joint seems to have worked well, but I shouldn’t have cut the silicone sheathing to do it, because the small hole I made to insert the plastic quickly ripped open wider and weakened the whole area.

LED Poles

Time To Reuse!

I’ll definitely have a use for these lengths of LED strip down the line, either in a future project or to give to my students for their annual LED Halloween costume midterm assignment, so overall I’m happy with how little waste this project generated.