"D"
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.


** A Germanium diode has a 0.2 volts drop at low currents - eg sub 1mA.

SMD versions must be made by someone.

But do you know any voltage drop is really NEEDED ??




.... Phil