By: Charlie DeTar, Christina Xu, Boris Kizelshteyn, Hannah Perner-Wilson
A digital wind chime with hanging acorns. Sound is produced by a remote speaker, and data about chime strikes is uploaded to Pachube.
Step 1: Brainstorming for a device that would represent ourselves
Our goal was to come up with a project which represented our personalities, and used an Arduino. We decided to use a LilyPad — but hadn’t settled on anything else. A week went by, and we shot ideas back and forth over email. We wanted to have it make sound, wanted to have it have something to do with nature, wanted to keep it simple enough that we could actually implement it in the available time.
The idea of doing a wind chime thing came up — the actuation is simple (just switches, no fancy temperature or humidity sensors to configure), so it seemed feasible. It provides nature, sound, and a nice form-factor in the LilyPad for that! But how should it work? Should it record the wind and play it back later with a button press? Should it transmit the wind knocks remotely to another place? Real time or shifted? Real location or shifted?
We got together, and Charlie brought some acorns; their natural beauty sealed the form factor of hanging acorns under the LilyPad. We decided to make the sound actuation real-time, but slightly remote (a speaker separate from the chimes), and to include a wireless module to upload the data to http://pachube.com.
Step 2: Materials and Tools
– 1.5 mm thick neoprene with fabric laminated to both sides for battery pouch
– Conductive thread
– Non-conductive thread
– Stretch conductive fabric (relatively small amount)
– Fusible interfacing “iron-on” to fuse conductive fabric to neoprene for battery pouch
– Non-conductive fabric (for the speaker cushion)
– Acorns (we used 6, but it’s flexible)
– Small plastic beads (to insulate thread)
– Fabric glue (to insulate and protect conductive thread knots)
– String to suspend everything from
– A Lilypad Arduino
– Bluesmirf Bluetooth module for Arduino
– A USB to serial connector for testing and loading your code onto the Arduino.
– Batteries (we used 3 AA)
– A speaker (headphones could work too)
– USB Bluetooth Adapter (optional)
– USB Extender Cable
– The Arduino programming environment.
– The Processing development environment
– Sewing needle
– Pliers (for pulling needle)
– Thimble (for pushing needle)
– Sharp scissors (for cutting fabric and thread)
– Soldering iron
– Multimeter (for finding shorts)
Step 3: Threading the acorns
The acorns serve both aesthetic and practical purposes. In addition to helping our chime blend in with a tree, they also weigh down the conductive thread to keep them straight in a windy world.
For our chime, we used 5 plain acorns. Decide about how long you want your windchime threads to be and cut 5 pieces of conductive thread about 2-3 inches longer–precision doesn’t really matter here, and it’s good to give yourself some room to tie knots with.
Thread your needle* with one of the pieces of thread and poke it into the acorn. Using your thimble, firmly push the needle until it is all the way into the acorn. Unless you are using giant mutant acorns, most of the needle should now be sticking out of the other side. Pull the needle all the way through using a pair of pliers. Then, pull the thread through until there is about an inch hanging off of the bottom of the acorn and move on to the next acorn.
When all five acorns have been threaded, line them up to make sure that the arrangement of the acorns looks nice to you. If you are satisfied, tie a knot at the bottom of each acorn (big enough that the thread can’t slip through the acorn even through vigorous shaking) and place some fabric glue on the knot to seal the deal.
Now, tie each one onto the LilyPad. You may find the needle helpful in this case. Spacing out evenly and avoiding + and -, loop the non-acorn-end of each thread into a port of the Arduino and secure it with a knot and fabric glue. At this point, BE CAREFUL not to get everything tangled up! Ours was such an issue that we ended up wrapping some normal wire around our thread to try to prevent tangling.
- Threading can be difficult, as conductive thread frays easily and wetting doesn’t help too much–use scissors to cut off any irreparably frayed ends and start over.
Step 4: Making and attaching the Knocker
Since we want to detect when the knocker hits a thread, the knocker should be something conductive. Any metal bead should do, but we decided to just wrap an acorn in conductive fabric. To simultaneously secure the fabric and to tie it to the Arduino, we got a long piece of conductive thread and used it to sew around the top of the acorn, creating a ruffle at the top.
The rest of the thread can now be used to suspend the knocker from the center of the LilyPad. To accomplish this, we created a criss-crossed X shape with thread on the bottom side of the Arduino (looping through holes -, a1, 1, and 9) , then tied the knocker’s string on to the intersection. By looping it through the – hole, we guaranteed that this knocker was going to be connected to ground–make sure, however, that no part of the cross touches any of the acorns’ ports, or it’ll create a short that will register as a note constantly being “on”!
Step 5: Sewing the battery pouch
It is nice to be bale to integrate the power supply of any device within the design of the whole. So we thought to include the three AA batteries necessary to power the LilyPad Arduino (and later on the Bluetooth module as well) in the hanging of the chime. Making a pouch for the batteries so that they could be stacked in succession and become part of the suspension. This construction proved slightly faulty since the pulling forces on the battery pouch ended up pulling the conductive contacts at either end away from making contact with the ends of the batteries. We were able to solve this by stuffing enough conductive fabric into either end. Which worked fine for the time being, but in future this should be revised.
So that we don’t have to sew the conductive fabric to the neoprene we can simple work with fusible interfacing. a think web of heat adhesive intended for textiles. simply iron it on to the conductive fabric first, be sure to use the sheet of wax paper between the iron and the interfacing. and be careful that the iron is not too hot or it will burn the conductive fabric. test on a small piece first. slight discoloration is okay.
Download the following stencil and print it out to scale:
>> http://www.plusea.at/downloads/TripleAABatteryPouch_long.pdf (coming soon…)
Cut out the stencil and trace to the neoprene and conductive fabric. You might have to adjust the measurements slightly if you use thicker neoprene. Other fabrics, stretchy or not, are not suitable for this purpose as they are unable to make such a great fit for the batteries. After tracing cut out all the pieces.
Remove the wax paper backing from the conductive fabric and lay out the pieces on top of the neoprene where they belong (see stencil). You can use the wax paper between the iron and the conductive fabric for extra protection. iron over the patches so that they are strongly fused to the neoprene.
Thread a needle with regular thread and begin stitching the neoprene together. first along the length and then both ends. you can insert the batteries while sewing to make it easier. And you can cut the hole at the very end to remove the batteries. make sure the hole is not too big. neoprene is very resilient and can take a lot of stretching.
Thread a needle with conductive thread. plunge into the neoprene at either end of the battery pouch and make contact with the conductive fabric within. use a multimeter to make sure you got the connections. and stitch multiple times to make sure the connection is good. you can define – and + by simply switching the direction of all the batteries. one of the ends will leave directly from its end of the battery pouch, the other will have to be brought down to the same end by stitching along down the neoprene. be extra careful that the thread never goes all the way through the neoprene, where it could make contact with one of the batteries or possibly the conductive fabric form the other end. use a multimeter to test as you sew.
Connect and isolate
When you have both ends + and – at the same end of the pouch. you’ll want to get them to the LilyPad Arduino. isolate the threads with glass or plastic beads and sew around the lilypad connections and glue before cutting.
Now the power supply should be working. What is missing is a way to suspend the pouch, LilyPad and its acorns from. For this, take some non conductive string and sew into opposite end of the pouch than the LilyPad. Create a loop or two loose ends that can be tied around the branch.
For more detail: Acorn Chime