Recently, as part of an iPhone development project I’ve been working on with the Institute of Zoology and Birkbeck, I had a need for an audio line in adapter so that we’d be able to record stereo audio from an audio sensor. The application tags audio data with GPS information as part of a citizen-scientist data collection project.

Strangely (or perhaps I didn’t dig around the interweb long enough) I didn’t find many resources for a home-brew line-in adapter and the ones I found were pretty vague and hard to follow. So Peter and I put our heads together and rolled our own. It’s a fairly straightforward circuit, but has a little twist, because the iPhone OS is smart enough to detect what’s plugged into the stereo jack. (The diagram above is a lot more clear than anything I found.) This particular project only required a left channel audio input to the monaural iPhone mic, but if you wanted to route both left and right channels to the mic, that’s represented by the dashed line.

The resistor+capacitor network provides a pull-up that the iPhone is looking for to detect whether you’ve got a standard stereo headset plugged in or whether you’ve got a microphone (i.e., iPhone) headset and can take a phone call with it. This particular circuit is tuned for the audio sensor we’ve been using, but is about the right spec for most audio recording purposes and works fine with the audio recording app that ships with the iPhone. The parts cost about £3 and I whipped one up in about 10 minutes!

Well, it’s 2010 and what a harsh decade it has been! To ring in the New Year on a positive note, I harvested an old edge-lit display mechanism from my stores and lit it up with a few LEDs and an Arduino. I used a simple pulse-width modulation (PWM) routine to do the fading. It’s not terribly exciting, but you can watch the video…

Spacehopper Demo

I’ve been working with my colleagues on a project for SonyEricsson around the release of their latest mobile phones series (Satio and Aino). The project involves using twitter to inflate a warehouse full of spacehoppers on a live webcam. The hoppers will be “released in the wild” as part of the product launch, and tweeters can suggest what their fate should be. The whole system uses an Arduino-controlled solenoid array which takes its input from a Ruby script which is listening to the twitter streaming API. Tweets sent via the API are used to randomly inflate one of the 49 hoppers on the array. The hoppers, username and the tweet message are displayed via a live feed. Sony Ericsson have posted the “making-of” video on YouTube, and I found myself simplifying the technical details, yet again…

Just read Danah Boyd’s excellent blog post on the twitter “backchannel” phenomenon and the difficulty it presents for speakers who are placed in a very awkward position. Her extremely negative experience at Web2.0 Expo illustrates how difficult it is for public speakers to cope with live (and often unmoderated) twitterstreams onstage behind them. The shift in the structure of this social discourse does not offer anything of significant benefit for either the speaker or the audience. Danah’s experience captures it better than I can and for the full scoop, head on over to her blog and read about it.  I, for one, certainly hope this is not the future of public speaking. And I’m no luddite!

Wow. It had to happen, of course. Shapeways have developed 3D printing in a material other than resin or polymer, the traditional materials for rapid prototyping physical objects. They can do it in stainless steel! The magic isn’t toooo surprising though, as they use the same techniques. Stainless steel dust is fused into a solid form layer by layer. The finished model is then bronze filled and baked. The piece comes out with a matte finish but can then be tumbled for a polished finish. They appear to be targeting the maker/craft community and I can think of a lot of fiddly parts that I’d need to make. But it’s still not as good as the 3D printer that the clever guys at EvilMadScientist Labs (rock on, guys!!) homebrewed, which makes 3D models in cane sugar!