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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
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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