[sdiy] iPod click wheel

[Titus Anderson]

Ars Technica recently did a review and autopsy of the iPod Nano, and they
have a picture of the click wheel on their site.

http://arstechnica.com/reviews/hardware/nano.ars/4

Just looking at it, my guess is that it works similarly to zero-force
elevator call buttons, which work by detecting a change in capacitance.
Looks like it also has five push buttons -- one in each of the compass
positions, and the fifth in the middle.

Not sure how hard it would be to create your own, but it seems to me
that if you could figure out the capacitance part, measuring the change
shouldn't be too hard.  My guess is that it measures the charge time of
an RC circuit on each pair of pads, and that determines where your finger
is.  A few years back I made a thermometer with a thermistor and cap, and
used a serial port to read it -- same principle, only now you have a
variable cap instead of resistor.

-- 
Titus Anderson                  System Programmer
titus.anderson at louisville.edu   Information Technology
(502) 852-8898                  University of Louisville

On Fri, Sep 16, 2005 at 07:03:25PM -0400, Aaron Lanterman wrote:
> 
> I was just fiddling with my iPod, and thought that it's slick touch click 
> wheel thingy would make a nice synth controller.
> 
> How does that thing work? Are the guts of it available for purchase 
> somewhere for good proper flidding about?
> 
> - Aaron
> 
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