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From: merithew@jessica.stanford.edu (Robert Merithew)
Newsgroups: sci.electronics
Subject: Busted Quartz Clock
Message-ID: <4966@portia.Stanford.EDU>
Date: 31 Aug 89 00:40:23 GMT
Sender: USENET News System <news@Portia.stanford.edu>
Reply-To: merithew@jessica.stanford.edu (Robert Merithew)
Organization: Stanford University
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I recently acquired a 1982 Audi 4000 with an analog in-dash electric clock
that doesn't quite work.  It apparently stopped working after a catastrophic
electrical system failure some years ago.  It seems that the clock motor
pushes the second hand backwards every alternate second (quite amusing to
watch, but rather useless as a clock).

The clock takes 12V DC and consists of a couple of capacitors, a resistor,
a crystal, a magnet coil around a couple of pieces of metal that form the
motor, and, of course, the inevitable mystery IC from Germany.

My question:  How might such a clock work?  Anyone recommend a book that
might explain the theory of operation of such a clock?  of electronic
clocks in general?  Anyone have any guesses about the mystery IC? (I can't
read the back of the IC without heavily damaging the clock, but I haven't
really got anything to lose...)

I called an Audi dealer, and (much to their amusement) discovered that
ordering a replacement clock from VW/Audi would cost me at least $160.
(must be a pretty special IC!)

I'll probably just slap a $2 stick-on clock on my dash anyway... I was 
just curious about how quartz clocks work.


-Robert Merithew

 merithew@jessica.stanford.edu  (internet preferred)
 MERITHEW AT SUWATSON           (bitnet)