Making a (literal) ThreadBoard constellation!
First off- obligatory explanation of what the heck a threadboard is. If you haven’t seen my other post, our TA Chris Hill for this course co-created this concept!
In essence, its a debugging tool for e-textiles. Its a specific layout of magnets inset in acryllic that allows for rapid prototyping using other magnets, or magnetic components. Specifically, magnetic thread is primarily used to create traces, and hence the name ThreadBoard.
Our first assignment to get familiar with the ThreadBoard was to light up some LEDs. With a coin cell battery, not much current and voltage was provided, so we could only light 1 LED in series and 2 in parallel. This was done in class, and in lab we were given an Adafruit Playground Classic. This allowed us to draw some more current, and we recreated the circuit in the third picture, this time all 3 LEDs had enough current to light. Unfortunately, I forgot to snap a photo of this- but here’s the schematic!
Now that we familiarized ourselves with the ThreadBoard, our next and final task was to tell a story using interactive elements, and nothing more than the ThreadBoard, some crafting materials, magnetic thread, magnets, and LEDs. No programming allowed!
I first decided on a steering wheel project but that didn’t pan out unfortunately (again- it seems like I forgot to take photos or something happened to this). I had a nice mechanism for a paddle shifter (using repelling and attracting magnets in tandem), but I realized I wasn’t telling a story.
It took me some brainstorming to come up with a new idea. I liked using magnets in an interactive way from the steering wheel idea, but I also wanted more of a “story”. I found my idea when I came upon some metal balls in the BTU Lab I was working in. Combining these with the tiny disc shaped magnets (also used in the ThreadBoard, which helped later) could make constellation-like shapes, as seen in the photos above. I had my “eureka” moment- I’d make a DIY constellation that lights up as you complete it! I found some blue foam as a backdrop and set to work.
I decided on a 4 LED/contact pad design, where the user starts on the star and connects to none, one, two, or three other contact pads. I used a hole punch to easily cut out two, and an exacto knife to cut out the star and right cut-outs. I then hot glued a copper pad folded in half to the foam, and then a magnet on top of that. The hot glue didn’t work that well, and one time forced me to start over as I misplaced hot glue between the copper and magnet- ruining the connection.
At this point, I set up a prototype circuit for the first two contact pads, to see if my idea would work (top-left). I also ripped out the white backing for the foam to allow more light from the LED to pass through (top-right). This, along with using foam instead of paper (which would have let even more light through for better effect) were two big mistakes which led to the scrapping of this ThreadBoard as the foam got stuck to the acryllic. However, in better news, after recreating one of the pads for better contact, adding some more magnets as risers, and some more debugging…mostly just bad contact…the prototype worked! I added the rest of the contact pads and solidified the wiring.
The wiring itself is rather simple. The idea is to string a single power line to the left contact pad. This pad will start every constellation. The user then creates a connection to another contact pad. This will bring the power over by closing the “switch” between the two contact pads, with magnets and metal balls. The power will flow from the second contact pad, back to a ground wire which is strung across the entire ThreadBoard. This closes the connection, and puts the two LEDs in parallel to each other. The power can be brought to any of the other contact pads, also creating parallel connections. I’ll attach the completed circuit schematic down below- which should hopefully make this make more sense.
It took a lot of finessing with the LEDs to get the right contact, and the sticky foam did not help at all. But in the end, I got it to work! And it worked flawlessly. I added some creative decoration and direction to the foam, and recorded two videos showing it off. Sorry for the video quality in advance- it’s hard to film and create a constellation!
Finally, I’ll leave off with the schematic for my ThreadBoard “Constellation” project. The switches are labelled in respect to the various connections you can make. You will realize that any and all connections will result in a parallel configuration with one to four LEDs. The start LED is always on, no matter what other connections are made. This is to help the user intuitively realize to start on that side, even in the dark. You will also realize that at least one connection (but not all) must be made from the left side- other connections will not be connected to the 3.3v line.
Thanks again for following this week’s project. Next up, I will be finishing the Logic Probe that I started last week. I hope this constellation lit up your night sky! Ahahahaha…ha…
