On Tue, 05 Jul 2011 21:46:06 -0700, D wrote:

I am a watch collector & repairer. I also have a fair, though somewhat
dated, electronics background. I have several early '60's vintage
Bulova Accutron wris****ches. These watches operate using a very basic
oscillator circuit which energizes a tuning fork via a pair of coils.
The tuning fork then drives the mechanical movement of the timepiece. A
basic description can be found he
http://www.timezone.com/library/horo...72882451976629

These are very cool watches to the collector. They are stylistically
very much of their era, and because of the tuning forks, they hum,
rather than tick. The problem is, these watches were originally
designed to run on a 1.35 volt mercury oxide cell (343) which is no
longer available. There is a 1.55v silver cell which will fit, but it
can cause some Accutrons to run very fast, and possibly even damage
them. At least one supplier sells modified cells with a component to
drop the cell's voltage to 1.35 volts. I think this is accomplished
with a surface mount type diode. Here's a thread on these cells in a
watch discussion, with pictures of the component added
http://bdwf.net/forum/showthread.php?t=75397 I would like to simply
insert an appropriate diode into the circuit of the watches as a one
time modification, after which I can use the much cheaper/readily
available silver cells. But, as I said, my electronic component
knowledge is late 70's vintage, so I'm not sure what component to add. I
know in general silicon diodes have a forward voltage drop on .7V,
germaniums, .3V, so I'm not sure how to produce .2V. A zener? A
Schottky? Anyone have any suggestions on what would lower the output
of the 1.55 volt cells to 1.35 volts, over the life of the cell? It
would have to be fairly small, about 1/2 the size of a 1/4 watt
resistor, or less.

TIA

Dan

I own a solid gold 1965 Accutron. My jeweler has a device he lays the
watch on, it listens to the mechanism and tells you how much the movement
is off time. He was able to adjust mine down all the way to about 30
seconds a month fast. I have no suggestion other than his suggestion that
there may be a retro-fit tuning fork out these somewhere. This was around
2004.

Do some research, you may be able to find a fix. I wouldn't screw with it
myself, that stuff is awful delicate.



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