HDD Clock

With a cupboard full of old hard drives and some spare time, I recently set about making a persistence of vision clock. Using the platter of a hard disk, a slot is cut to allow backlighting to be emit. When the disk is spinning at 5400rpm+ and backlight constant, the disk appears opaque, as the slit is ‘refreshing’ each point of the revolution faster than our eyes. The trick is to measure the revolution time then flash or change the backlight colour at a fraction of this revolution time at the same point each revolution, in order to create a light segment. For example, flashing the light at a frequency twelve times the disk frequency in phase with the disk will create 12 light segments:

f_{light}=12.f_{disk}=\frac{12}{p_{disk}}

Expanding on this, one can create a light based clock, which takes some getting one’s head around on first sight!

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Setting Up a USB WiFi Dongle on Raspberry Pi Arch

For my AirPi, I needed to make my Raspberry Pi wireless. Being the man of thrift that I am, I found the cheapest dongle on eBay: a (Digitaz) RaLink RT5370.

Now Arch isn’t exactly plug and play, but that’s part of the fun. Plugging it in, the only way you’ll know it is there is using:
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AirPi: DIY Airplay Speakers using Shairport and a Raspberry Pi

We have speakers in all the ground floor rooms of our house, all driven from the same amp. It’s neat but controlling the input requires going back to the amp.

Surrounded by iDevices too and with apps like iPlayer, Spotify and home share on iTunes, being able to throw audio to the speaker system had to be done. Que Airplay, however, this requires a nice Airplay amp or getting an AirPort. I then found out about Shairport, a program that emulates an AirPort’s Airplay function. With a Raspberry Pi kicking around, I had just found its new job.
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Musical Rainbows in the Van

I always intended on creating my own driver for the LED lights in my van but with the thieving skum pointlessly taking the remote for the included unit, I was spurred into action. Having installed a sound system, a musical light system was a given, to enable the van to live up to the Bang Bus name it has acquired (of certain definition!).
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