Archive for the ‘electronics’ Category

Project Idea: Arduino Sous-vide Cookery

28/04/08


“Sous Vide Machinery” by
Ginger Gross

We’ve been glued to the BBC 2 series The Great British Menu We came across it during the week where Sat Bains and Glynn Purnell fought it out to represent the Midlands. They both used a strange cooking technique that I had not encountered before whereby meat is vacuum sealed in a plastic bag and then cooked for a very long time in a water bath at a constant surprisingly low temperature. The results seemed amazing. I asked Fabien (a knowledgeable food-loving colleague at work) and he pointed me to the whole new word of sous-vide cookery. I haven’t yet explored the cost of a large water-bath (or a vacuum packing machine) but it did strike me that this may be a great project to try on the Arduino, and I found an example water-bath electronics project online that may help.

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Project idea: visualizing radio frequency whitespace with ferrofluids

24/04/08


Old seeping oil
by dumbledad

A few years ago we did some interesting work on using part of the DAB radio network in the UK for datacasting – i.e. for sending non radio content like video files or emergency procedures to mobile devices. Several of the people involved in that project have gone on to think hard about whitespaces i.e. what can we enable in the areas of the radio-frequency spectrum that are unlicensed or unused. Recently Gary Tonge and Pierre de Vries wrote a piece for Communications & Strategies (no. 67, 3rd quarter 2007) called “The Role of Licence-Exemption in Spectrum Reform”

Motivating countries to allow licence exempt spectrum is a difficult but an important debate. The difficulty is that the argument rests on the idea that licence exempt spectrum will encourage innovation, and unexpected successes (like wi-fi) will flourish. Of course it is hard to map out the unexpected.

Another problem is that people’s understanding of radio spectrum use and its actual use differs. Consider these two interesting visualizations of radio frequency.

First off I picked up http://spectrumatlas.org/ by http://www.bestiario.org/ from Richard’s trends blog. It’s a 3d visualization of the RF spectrum, an atlas of electromagnetic space. Using it you are left with the impression that the RF spectrum is jam packed with legitimate and useful services. So let’s instead look at a radio frequency spectrogram that I first encountered in an earlier paper by Gary Tonge. It’s taken from an Ofcom consultation document in their 2004/2005 spectrum framework review: “Spectrum Framework Review: A consultation on Ofcom’s views as to how radio spectrum should be managed

The key may be difficult to read, but the blue parts of the graph are spectrum not in use at the time the frequency was scanned. This scan was done over a twenty four hour period in Baldock (near where I live) in 2004. It tells a very different story form the previous visualization.

The Ofcom spectrogram is a very clear way to see how much of the radio frequency spectrum was not being used during that day. I’ve been wondering if this might be a fun thing to visualize using ferrofluids – hence the oily picture at the top of this post. Some of the more hardware savvy people in our team at work have been starting to think about ferrofluids and I’ve been on the look out for an application. One magical thing about ferrofluids is that they make something invisible shockingly visible. Normally they just look like oil but when a magnet is held underneath they adopt physical shapes dependent on the magnetic field. There are some awesome videos on YouTube and some lovely photos on flickr like this one from David Nicholai:

So perhaps this could be used to visualise the invisible radio frequency spectrum. I imagine using a small pump, beam, and sump to produce a sheet of oily ferrofluid over a sheet of plastic or glass. Behind the glass we could use Phidgets or an Arduino to drive magnets mounted on a motorised linear potentiometer. This would then result in elements of the graph being rendered as lumps in the otherwise sheer sheet of oil, which I imagine would look amazing. Interesting? Mad? Comments please.