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Has anyone adapted surplus computer parts for other uses? For example:
adapting on old sound card for use as
an amplifier. If so, please tell what you
did and how. Also, can someone
explain the similarities and differences
between audio CDs and DVDs?
#6081 Paul Vandervort
How can I configure a small
LCD display as a voltmeter and/or amp
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110 June 2008
Okay, I'm a rebel. I don't have nor
do I want another two year commitment for cell service (or for that matter
a dual data/voice plan). Just pay my bill
and use my old(er) cell phone. To the
point: Several years ago, I'd seen a
device that plugged into a laptop's
modem port and then to the headset
port of a cell phone, and presto — an
Internet connection! All that I can
figure out is the interface device must
have somehow produced a tone for the
modem to believe it had a live line.
From there, it was a simple matter of
pushing 'speed dial' on the cell phone
and away you went -- surfing. Do you
have any ideas about this and how it
could be built from scratch? Better yet,
could there be something built that
would handshake between the data or
[#3084 - March 2008]
I would like to use the sensor from
a laser mouse for a rotary encoder in a
robotic arm. How can I read from it,
using an MCU? My plans are to mount
it inside a joint on the arm pointed at
the side wall, read the distance, then
translate that into rotational degrees.
What you are looking for is called a
quadrature encoder, and was used in
the older opto-mechanical mice. It
consists of a slotted disc and two
infrared sensors opposite of an infrared
LED, coupled through a friction gear to
a ball. Two of these assemblies — 90
degrees mechanically rotated — give X
and Y coordinates. The light beams on
the disc are arranged in a way that the
output is equally spaced and the two
signals are usually called Channel A
and B. This results in an output of 90
electrical degrees difference at constant speed — hence, the quadrature
encoder name. The spacing and size
will determine the resolution of the
encoder and values of 200-2,000