Email

Donate Button

Tardis-Light

Background:


A friend of mine, Alex, is building his own Tardis, and needed a hand with the light on top. I cobbled this together in a couple of hours and thought I'd share it. 

Hardware:

A standard Arduino Uno board,  

about 20 LEDs worth of Adafruit's Adressable LED strip. 

The wiring is very straightforward, and is the same as the examples on the Adafruit website. For a section of strip this size, I'm happy for it to be powered over USB. 

For prototyping, I put the strip and circuit board inside a softdrink bottle to hold the round shape. The finished version will need a proper mounting and diffuser, of course.

The search for the perfect 'Swoosh':

The swooshing light and grinding noise as the Tardis materialises, is such an iconic part of the TV show, so I wanted to get it working nicely. I haven't checked with old episodes yet, but this seems to match my memory and people's perception.


I started with a simple sine-wave generator, and allowed modifying it so that it has a baseline-on value that is never ducks below. I also added a 500ms pause before it starts the next cycle. 

The result was nice, but seemed a little wrong. So I ran the result through a shaping filter (basically the output is raised to the power 1.1), which seems to give a nicer on time, whilst still having a bit of decay in there like an old bulb cooling. 

All parameters are broken out as variables, and can be tweaked easily. 


Code:

The code is attached at the bottom. You'll also need the LPD8806 library from Adafruit's github, here:
https://github.com/adafruit/LPD8806

When it's on display, the Tardis light has to synchronise with the sound from the PC. So I made a simple serial protocol that allows turning the lights solid on, off, doing the takeoff swoosh, and sparkling blue, etc. from the control of a laptop.





Č
ċ
ď
tardis_light_v01.ino
(5k)
Gavin Smith,
Apr 14, 2013, 4:12 PM
Comments