Being and speaking at 25C3

You know that weird period between Christmas and New Years, when nothing really gets done? This year, I spent mine at 25C3; the 25th annual Chaos Communication Congress. Four thousand-odd geeks from around the world gather to share their ideas, hack, talk, game, build, start collaborations, and more. I'd never been to a hacker conference before, so I decided to jump in at the deep end and give a talk on Formica! It was a truly incredible experience...

Submitted by jeff on Tue, 01/13/2009 - 15:53. categories [ ]

Sapphire Cocktail Ring

I made this sapphire ring as a Christmas present for Faye. It's minimalism is unusual for a cocktail ring, but I think its impracticality puts it squarely in that category!

Citrine Pendant

I made this surprising, minimalist pendant as a Christmas present for Flic.   


Amber Ring

My old friend John commissioned me to make a ring for his sister, Lou. Well, Lou actually did most of the commissioning, John just paid! She wanted something in amber and silver. After a bit of thinking, I came up with this concept sketch...


...and after a bit of building, ended up with this:


Please post any questions you have in a comment, below. We will answer it, and add it to the page.

Test Points

Since connectors are expensive and bulky, we designed circular contacts into the PCB layout for testing the circuit and flashing the MSP430. I made a simple "bed of nails" test jig with spring-loaded contacts to mate with these pads.

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TODO: write this

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Charging Contacts

The robots have two skis soldered to the bottom of the PCB and two charging prongs on the top. As well as supporting the front of the robot, the skis are ground terminals for charging. They make contact with a foil pad in the charging bay. The angled charging prongs are designed to wedge under the aluminium rail in the bay, which is powered.

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The wheels are the only components on the robot which require any considerable custom fabrication. Surprisingly, we couldn't find a commercially available rubber wheel a few millemetres across! We had a look around for suitable rubber washers, etc, but found nothing. Instead, I developed a simple method of mass producing the wheels from neoprene sheet.

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Circuit Design

Circuit Design

The circuit design aims to minimise cost, area and component count. In this section, subcircuits will be introduced and discussed.


An MCP1702 3.3V linear regulator provides a stable source for the MSP430. Its maximum supply voltage is too low for direct connection to the battery and in any case, the noise produced by the motors would likely be too great.

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