The World is Your Squeaky Instrument*

From kitties to wooden doors, the world becomes a source of squeaky fun with the Drawdio. Originally designed by Jay Silver, the Drawdio allows you to turn nearly everything you touch into a theremin.

BOM:

  • Drawdio PCB– Note that if you purchase the kit, you’ll receive through hole components. However, the board also features footprints for SMT components should you wish for a build with a lower profile.
  • TLC551 or similar low voltage ‘555 timer chip.
  • Glove made from non-conductive material. If yours contains metallic thread or fabric, check with a multimeter to be certain it won’t accidentally cause any shorts.
  • CR2032 and CR2032 holder or BR-2032
  • Eye pins
  • 8ohm speaker– This is larger than the one used in the kit. The increased surface area is used to conceal and protect other components from snagging on my coat pocket.
  • Conductive thread (usually has the resistance of 28ohms/ft, which isn’t enough to necessitate changing any of the original components of this project.)
  • Q1: PNP transistor, EBC pinout (such as PN2907 or 2N3806)
  • C1: 680pF ceramic capacitor
  • C2: 100uF / 6.3V capacitor (or higher)
  • C3: 0.1uF ceramic capacitor (104)
  • R1: 1/4W 5% 10 MEGAohm resistor or 1/4W 5% 20 MEGAohm resistor
  • R2: 1/4W 5% 10 ohm resistor
  • RA: 1/4W 5% 10K resistor
  • RB: 1/4W 5% 300K resistor
  • Loctite adhesive or hot glue
  • Solder

Optional:

    • Needle threader- Helps you thread the needle with minimal fraying.
    • Beeswax- conductive thread likes to knot, which the beeswax helps prevent
    • Fray Check– Use a dot on your knots before snipping off the excess thread. This helps prevent any fraying and un-knotting.
    • Fabric paint/ hot glue- A thin layer over the conductive thread helps minimize oxidation and fraying.
    • Shielding tape or conductive fabric, allows you to use less conductive thread and have more solid, conductive points of contact or “playing” surface area. Nota Bene many conductive fabrics fray easily.

Tools:

Assembly:

Adafruit has already created an awesome tutorial to which we’ll only make a few modifications.

The first few steps are the same. Please follow the tutorial steps until you get to attaching the speaker.

  • Before attaching the speaker, we’re going to solder an eye pins into the + and – holes marked for the battery holder. We’ll use these to sew the board to our glove and the coin cell battery later.

Then, attach the speaker following these modified steps:

  • If the speaker you are using doesn’t have wires already attached, follow the tutorials instructions for soldering wires in place on the speaker and on to the PCB.
  • The difference in the mounting of the speaker is that instead of looking like this:

    we’re going to make it look like this:
  • Glue the speaker on top of the soldered components using Loctite or hot glue
  • After the glue has dried. Cut a piece of conductive thread about a foot in length. Thread your needle and tie a knot in one of the ends. Apply a drop of Fray Check on the knot before cutting off any excess thread.
  • Now is the fun part of sewing the board on top of the glove to the battery holder on the inside of the glove. Since the back of a glove doesn’t tend to go through all of the stretching that the wrist band does, I chose to place the battery holder just beneath the PCB.

Lynne Bruning has a wonderful video tutorial for tips to sew components to fabric here.

  • After connecting your battery holder, be sure to touch both ends of the PCB to check if the circuit is working.
  • Using a tight running stitch, sew one end of the PCB up to the tip of your middle finger.

  • Create a pad with conductive thread at the tip of your middle finger. After knotting the thread, apply a dot of fray check and snip off any excess.
  • With another piece of conductive thread, sew from the opposite end of the PCB to your thumb where you’ll create another conductive pad.

You should now be able to “play” the world to your heart’s content!

* This post was originally written for the OSH Park blog, and published on November 20, 2013.

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