## Ben North's blog.

Covering various topics, usually of a vaguely nerdy nature.
Contact: ben@redfrontdoor.org

08 June 2015

## Faint amusement from arrows

In logic, we talk about propositions, giving them names, say p or q. For example, p might be the proposition 'it is raining', and q the proposition 'I will get wet'. Then to represent the proposition 'if it is raining then I will get wet', we can say 'p IMPLIES q', which is often written […]

08 April 2015

## A game of multiples and divisors

I saw an interesting number-based game at the 2015 Young Scientist show. This post derives, using brute force, a winning strategy for the game and implements it as a 'human vs computer' setting.

16 January 2015

## Post-specific Javascript and CSS in WordPress

A couple of recent posts here — An oscillator from a jam-jar lid The value of a second opinion — required some post-specific Javascript and CSS styling. It took me a little while to figure out how to achieve this, given my limited exposure to PHP in general and WordPress programming in particular. This is […]

16 December 2014

## The value of a second opinion

You feel ill and go to a doctor. She does a test and says 'you have a 70% chance of having the Lurgy'. You go to a different doctor, who does a different test, but also says 'you have a 70% chance of having the Lurgy'. Given these two test results, what are your chances of having the Lurgy?

09 November 2014

## Tiny patch to git

A one-character documentation fix for 'git'.

17 July 2014

## Failure: playing video from audio cassette

The idea for this project came from a few different places: Curiosity about how cable modems actually transmit ones and zeros along the coax cable. This led to some reading about the various modulation methods used. Code I'd written to read the data on cassette tapes containing files from the Dragon 32 computer of my youth. […]

08 June 2014

## A Simon-playing robot

My 7-year-old daughter and I built a robot which plays the memory game 'Simon'. Servos use string to pull 'fingers' made out of Lego, pressing the game's buttons. Phototransistors sense which lights are flashing, with an Arduino controlling everything. It successfully plays a complete game of Simon!

16 May 2014

## Free Software collaboration at the National Library of Ireland

RTE recently carried a news piece announcing the release of a large volume of historical digital images by the National Library of Ireland. One detail in the piece caught my eye: it quoted the library's Digitisation Programme Manager Sara Smyth as saying Since 2010, we have overhauled our digitisation workflows and put in place key […]

20 January 2014

## An original escapement design?

© Trustees of the British Museum[source page] On a recent visit to the British Museum in London, I was interested to see a very curious escapement mechanism in one of the clocks, a creation of Thomas Tompion in the 1670s. I am certainly no expert on clocks, but I had never seen an escapement where […]

27 November 2013

## An oscillator from a jam-jar lid

Fiddling with a jam-jar lid suggested its tamper-evident pop-up button exhibited hysteresis, and so I did some experiments on a blackcurrant jam lid to test this. Adding weight 50g at a time, the lid flexes very slightly, but stays popped up with 800g on top. It pops down when you add 50g to make 850g. […]