I’ve been working in theatres for about 5 years. I’m a lighting technician for a few different venues and production companies, but I specialize in the engineering solutions behind our shows; I’m a Mechatronics Engineering student at UoN, so I’m naturally drawn to elegant solutions and good problem-solving. I was approached by a coworker who was putting on a production of 'Freaky Friday: The Musical' and needed a way to put lights inside an hourglass prop - every other detail was left to me. I pretty much got to work instantly!
The hourglass is two halves of a similar design that mechanically interface with two dowels, locking the two together. At the surface level, each side is 40cm of WS2812B tape, an Adafruit Huzzah Feather V2 running WLED, and two sets of batteries to power the whole thing. One specific requirement I set was that it had to take DMX control from our lighting console. For the uninitiated, DMX is a control protocol specifically for theatre lighting solutions. In this case, it takes DMX over WiFi, also called ArtNet. This allows us to write directly to the pixels from our lighting console without an abstraction layer to control the pixels.
Step 1: The PCBs.
I was given the project on a super-tight deadline, so my usual “sit around and think about it” and “prototype heavily to lock ideas into place” just wasn’t going to work this time. I knew I wanted to use WLED, but I knew very little else about what form this project would end up taking.
Perusing the WLED Supported Board List, I was looking for the following:
- In stock at Core Electronics.
- Internal Battery Management and Li-Ion battery connector.
- USB-C is nice to have to charge backstage with existing and standard phone chargers.
One solid option emerged with all three of these: the Huzzah Feather V2.
That sorts out control of the pixels. Now onto the power.
Anyone who has ever worked with any amount of LED strip will tell you that they are a huge power drain. While the WS2812B datasheet tells you each LED will draw about 30mA at full White (255 Red, 255 Green, 255 Blue), this is more of a suggestion than a hard and fast rule. I was able to power 300 pixels (the LED strip’s supplier told me 5m @ 60pix/m would require an 18A supply) on a 3.6A supply, and while it wasn’t full brightness, it was what we in the industry call “eye-candy bright”. Bright enough to see the effect working, not bright enough to light a stage.
Step 2: The Batteries.
Because I didn’t know what my battery solution was going to look like, I put a 5V voltage regulator with a huge input range to make sure I wasn’t restricting what my battery solution could be in the end.
Finding appropriate batteries came easily:
With a 3-hour show (half an hour of walk-in, 2 hours of show, and another half an hour intermission), and approx 200mA current (as specified by the Feather datasheet with WiFi and processing load), I found that the minimum size should be 600mAh. This is obviously not wise to source a battery that dies at the end of the show. Easy solution here - double it!
A 1100mAh 3.7V battery with the same connector as on the Feather was quickly acquired from Core Electronics. This gave me a neat 5.5 hours of run-time, so that was sorted.
For the LED Strip Battery, I sourced two 2600mAh 18650s to go in series to give me 7.4V at 2.6Ah. For 33 pixels, my current at 5V nominal should be about 990mA at full power. This would give me 2.62 hours of run-time from full; however, knowing these LEDs would only be on for a few minutes at a time in the show, and not on for more than 30 minutes total, I decided to risk it on two batteries.
Step 3: The Assembly.
To install the LEDs and affix them to my assembly, I 3D-printed a cylindrical helix shape with enough space in the gap to stuff my LED strip to fill the hourglass with LEDs. I put an extruded 10mm post on the end of it, the same size as my largest drill bit, to then sit the LED assembly in a drilled hole. I then drilled another hole where the LED cable comes out of the helix to route it down to the controllers, just underneath. This worked a charm!
Oh - and the magic for putting it all in the underside of the hourglass? Double-sided tape to the rescue.
Construction:
The construction wasn’t handled by me, but rather done by a local Men’s Shed - they did an absolutely fantastic job; from the moment I had this thing in my hands, I was absolutely stunned. It’s a solid wood construction, mostly glued and screwed together, and an MDF top plate where the wine glasses sit. While the construction is a masterpiece, it’s not my department, so I know the bare essentials. Because the hourglass is a central part of this musical, we’re not the first people to try this, however. Stuff Ivan Made hosts a fantastic rundown of his build, which was our inspiration for this project; however, with some modifications - more on this later.
The “hour-glass” part is actually two halves of plastic wine glasses that have been cut in half. It wasn’t our idea however - it was borrowed from another creator who has also done this prop. They really sell the project as a cool-looking prop that does look like a giant, scaled-up hourglass. When the strips were installed on the prop, it looked a little silly - it was visibly obvious that it was an LED strip; in the show, it’s supposed to give off “spooky magic” vibes, and this just wasn’t it. While a few options crossed our minds, the one that seemed easy, cheap, and good-looking was quite cool - cling film. Scrunched up and stuffed around the glass, it really diffuses the light well, and this did seem to be a popular approach by other prop people.
WLED:
I first ran into WLED a few years ago when I first started playing with Wemos boards and flashed a few lights. “Cool”, I thought to myself. It has vastly improved since, and the addition of many features has really expanded its usage, especially in theatre. First, it’s worth noting that this prop operates on WS2812b, a serial RGB daisy-chain protocol for addressable chains of thousands of LEDs driven by one GPIO.
Anyone who has worked or volunteered in a theatre should know DMX. Developed in 1986, DMX512 is a great little protocol that looks and acts a lot like RS-485 - it is capable of sending 512 channels of 0-255 (512 channels are called a universe), which all correspond to different attributes of a light. Some lights just take 1 channel (low to high), while some take up to 50 (red, green, blue, zoom, intensity, strobe, etc), or even higher.
At its core, DMX is just 3 strands of copper that move a signal from the lighting controller (console) to the lights (fixtures), and while that might sound like enough, it barely is nowadays. Some shows you find in bigger venues might be running anywhere between 4 and 30 universes for all of their lights - if an RGB pixel takes 3 channels, think of what 50 meters of LED strip will take! Because a cable can only carry one universe, a 30-universe show would need 30 cables running from the console to the stage - that’s really annoying. Enter, DMX over IP. DMX over IP is a clever way to run thousands of DMX universes over a standard Ethernet network with super high reliability. It’s now the industry standard for bigger shows - and for good reason.
Two major protocols of DMX over IP cover 99% of the use-cases: Art-Net and sACN.
While lighting technicians will fight until the cows come home about which is better (obligatory XKCD), I have personally always had quick success with Art-Net, and have found sACN quite complex for my applications. While these do transfer over standard IP networks, and by extension, WiFi, this is absolutely not recommended by anyone for a variety of reasons. However, I don’t find any fun in rule-following, so I chose to do it over WiFi anyway - the microcontrollers already had WiFi built-in, so it was super easy to configure WLED to hook into our show network (Unifi U6+, which had huge coverage and awesome, reliable speed).
All this effort came down to one goal: controlling the hourglass directly from the lighting console. We looked at other solutions - actor-triggered buttons, messy Python scripts sending Art-Net, even mobile apps - but none gave true control. Our lighting designer also wanted full pixel-level control. With WLED, we achieved that: each pixel has 3 channels (RGB), giving 99 channels per side (33 pixels × 3). They patch into the console like normal fixtures - only these are wireless and battery powered.
In the end, our WLED solution was a Feather Huzzah V2 on a static IP sitting on the same VLAN as the lighting console, getting directly sent its Art-Net universe (so not to inundate the little processor), set up to map Art-Net to WS2812b: 33 pixels per hourglass half.
Download STL and design files for the WLED Hourglass Theatre Prop.
