Monthly Archives: February 2014

Visit to Access Space Sheffield

accessOut

I visited Access Space in Sheffield, where I enjoyed a two days crash training in using the command line and shell scripts in Linux. Initiated by James Wallbank and the Redundant Technology Initiative group in 2000, Access Space is arguably the first open source/community computing creative technology labs in the UK. The space is open several days per week, with two main areas: the Media Lab where visitors can access a Linux workstation for web access, design, programming, etc. A code-protected door opens on the Refab Space which hosts the digital fabrication machines (laser cutter, CNC router, several rep rap 3D printers), a lot of recycled computing gear and several solid workbenches.
During my stay I saw lots of activity in both areas, including a Sheffield Hardware Hackers meeting (every monday 6pm), and the laser cutter was pretty much always busy.

James is a great host, busy with many projects including his latest business adventure Infinite Crypt. He is always keen to share on topics of technological accessibility, community development and techno-social trends. I recorded an audio interview where he gives us his insight on Access Space and thoughts on the opportunities offered by digital fabrication technologies.

Interview with James Wallbank in Access Space Sheffield, 26th February 2014

Supercapacitor + Raspberry Pi

I have been interested in supercapacitors for a while. These components are boosted up versions of the humble capacitors found in most electronic products. A capacitor is a component that can store energy, in a similar way to a battery. Normal capacitors – aka caps – only take very small charges (typically measured in Microfarads), and they are often used for cleaning up spikes and noise in power supplies. Supercaps can store much more (measured in Farads), which presently makes them almost suitable as battery replacements.

scrapBatteries

What’s wrong with using batteries?
– They take a long time, and fairly complex charging circuits, to charge. A super cap can be plugged in a standard power supply with addition of just two components, and charge in minutes.
– They have a limited life span, generally around 1000 charges, after what they have to be recycled, a tricky business. In theory, a well-treated super cap will last almost forever.

I have run a couple of tests with current supercapacitor technology. I found all the info I needed about supercapacitors in this instructable.

Super capacitor battery, 8V 120 Farad

One if my experiments was to build an 8.1V, 120 Farad capacitor array, that should be sufficient for powering a small robot or microcontroller. It is made of 6 x 360Farad, 2.7V supercaps. First test: to supply power to a Raspberry Pi. It works fine, but with this configuration (8V 120F converted to 5V) I only get approximately 15 minutes of operation, and that’s without powering a display.

The bright side is the speed of charge, around 3 minutes with my bench power supply (2.5A).

Erm… Not sure what these supercaps will be good for, maybe a secondary power for mobile robot. The fast recharge rate could make it a good combination with a conventional battery to provide continuous operation.

Dynamo mini audio amplifier

Finally finished the mini audio amp I started when I visited Flowering Elbow. I fitted a supercapacitor array inside the amp, that gives approximately 20 minutes of operation when fully charged. Charging it with one of my modified dynamo torches takes 3-4 minutes.

Finger dancing optional. Music is Chocolate by Syrup.

The Magpi, Raspberry Pi magazine

I am gradually getting to grips with the Raspberry Pi, and I have stumbled upon a great online/hardcopy resource called The Magpi.
Currently at issue #20, The Magpi started in 2012 to deliver a monthly selection of articles written by enthusiasts about various Raspberry projects, features, and culture. All the issues are available online, and are a perfect repository for beginners and intermediate Rpi eaters.
The feel, layout and content of the magazine bring back a community based DIY computing spirit very close to that of the 1980s, which I guess the Raspberry Pi initiative is very inspired by.

magPi19magpi9

The Magpi is currently running a kickstarter campaign, already 341% funded with 13 days to go!