learning the ropes

Taking a look back at the breadboarded circuit always turns up something I’ve neglected on the schematic: in this case, it’s the vibrating motor.

I’m also a little concerned; I haven’t heard the amplified sound from the MP3 player through a circuit we had on another breadboard.

Work continues on the schematic for Dust. I have spent hours in Eagle drawing this thing.

Design Questions:

• Current design will require two USB ports (Arduino + MP3 player). Will it be necessary to include both of them on the PCB?
• How much current does the circuitry require?
• What type of battery will we use to power the circuitry?

I also started creating a PCB design. I want to print it out this afternoon to see the physical size and see if this corresponds with the size we want to make the wearable item.

For the past two days I’ve been building up the Dust prototype circuit.

So far I’ve gotten away with entirely found parts… This is fine for the breadboard, but for our final wearable version, we’ll need to reduce the size significantly.

• Relays are Omron G5A and an OEG 105D. These are much too big. I would prefer Omron G6H (high density)
• TIP-120 Darlington transistors could be replaced by 2N3904 transistors (or maybe there are SMD transistors). I originally wanted to avoid using relays to drive the MP3 player, but our tests with transistor-only circuits were unsuccessful.
• The Coby MP3 player is small, but the Sakura (from the designer of the MAKE DaisyMp3) is smaller — and open source.

Remaining tasks:

• Writing the Arduino code
• Testing the LM386-based amplifier

I’m working with Shinyoung on a project called “Dust” for Wearables.

“Dust” is a discrete, wearable character who offers spoken affirmation and support in response to “deflated” gestures.

Initially we tried sensing a sigh in order to trigger Dust’s affirmations. We planned to mount a stretch sensor inside a waist-belt and sense the expansion and contraction of the wearer’s diaphragm. Preliminary experiments with the stretch sensor did not yield favorable results. The stretch sensor seems to be optimized for applications involving greater ranges of motion.

We decided to try a different approach. It may be possible to use pleated material with conductive thread or fabric between the pleats to sense the sigh. In the pictures below, I am pleating a section of fabric to create a prototype of the gesture sensing mechanism.