Xref: utzoo sci.electronics:4420 rec.ham-radio:7228
Path: utzoo!utgpu!watmath!watcgl!awpaeth
From: awpaeth@watcgl.waterloo.edu (Alan Wm Paeth)
Newsgroups: sci.electronics,rec.ham-radio
Subject: Modifying Electronics, LED clocks, Hobbies
Message-ID: <7188@watcgl.waterloo.edu>
Date: 7 Dec 88 22:48:41 GMT
References: <2082@puff.cs.wisc.edu>
Reply-To: awpaeth@watcgl.waterloo.edu (Alan Wm Paeth)
Organization: U. of Waterloo, Ontario
Lines: 39

In <2082@puff.cs.wisc.edu> perry@garfield.CS.WISC.EDU (Russell Perry) writes:
>I've had this idea to take a LED clock and make it display something other than
>the time, but I don't know much about the things enough to rip it open and
>experiment.  Does anyone know how I could go in and change the display...

As Henry Spencer has pointed out, this is near impossible.
If you are set on "hacking" a wrist-watch, here are two suggestions:

(1) remove the crystal and file it down slightly (to reduce its mass). If you
    can make it run at 366/365 normal it will now tell "star" (sidereal) time.
    Graphite pencil lead can weight it back up again should you overshoot.
    (This technique was used by hams before freq synthesis became common).

(2) Buy a Casio-style "databank" watch. I've seen them at K-mart for $75CDN.
    They include a 4x10 char display (5x7 dot characters). If you are of
    hobbiest persuasion, then you can try to masquerade the signals sent to
    the watch by its docking port and get interesting text to appear.

----
This entire subject highlights a lament of mine. As consumer electronics
become more integrated (figuratively and literally) we trade off the pro's
of mass-produced, inexpensive, one-chip designs agains the con's of having
virtually no end-user means to tweak said device into a related application.

For instance, I know of a EE-hobbiest in LA who wanted to wire up all rooms in
his dream house with Star Trek-like "control panels". Mark decided that it was
cheapest to place a LCD pocket television in each room and assign a unique UHF
channel to it. However, this implied that he could no longer address pixels
directly. Instead, he would have to send a modulated video signal (I'm not sure
if he finished). For him, the good news was lots of scanning and drive logic
electrically and physically matched to the LCDs, in a small, package at less
than $100 per station (and maybe you could put the +12 on the coax and just
run one cable?) The bad news was that he couldn't get around the tuner and
demodulaton function implicit in a chip meaning he has to emulate a small UHF
tv station to "talk" any station.

    /Alan Paeth
    Computer Graphics Laboratory
    University of Waterloo