[time-nuts] Measuring the accurcy of a wrist watch

Robert Darlington rdarlington at gmail.com
Sat Apr 19 14:37:42 EDT 2014


Industry doesn't use microphones.  It's piezo pickups or inductive pickups
(coils) for things like tuning fork movements in accutrons.   For quartz
they use probes.

http://forums.watchuseek.com/f6/watch-timing-microphone-646148.html


On Sat, Apr 19, 2014 at 11:12 AM, Chris Albertson <albertson.chris at gmail.com
> wrote:

> On Fri, Apr 18, 2014 at 10:37 PM, DaveH <info at blackmountainforge.com>
> wrote:
>
> > Hi Chris
> >
> > My concern was not the magnetization of the watch movement but the
> > induction
> > of eddy currents into the balance wheel which will cause drag.
> >
> > The act of moving the watch into the field of the pickup could cause the
> > watch to start running more slowly. You will be getting a strong signal
> but
> > it will be the wrong signal.
> >
>
> What is the magnitude of this effect?  Would anyone know the relationship
> between field strength and watch speed.   For example the strength of the
> Earth's  magnetic field changes over at least a factor of four in different
> parts of the world.  Is this a seconds per day or seconds per decade kind
> of problem?
>
> But yes I agree forsaking serious measurements I'm make a purpose built
> coil.  Or actually like I said two of them wires in anti-phase.
>
> But even then, it can't measure a mechanical watch.   I think a microphone
> would be best.
>
>
>
>
>
> > Dave
> >
> > > -----Original Message-----
> > > From: time-nuts-bounces at febo.com
> > > [mailto:time-nuts-bounces at febo.com] On Behalf Of Chris Albertson
> > > Sent: Friday, April 18, 2014 08:44
> > > To: Discussion of precise time and frequency measurement
> > > Subject: Re: [time-nuts] Measuring the accurcy of a wrist watch
> > >
> > > On Thu, Apr 17, 2014 at 11:12 PM, Hal Murray
> > > <hmurray at megapathdsl.net>wrote:
> > >
> > > >
> > > >
> > > > Steel makes very good springs.  Are there any non-magnetic
> > > materials that
> > > > are
> > > > close?
> > > >
> > >
> > > I think they can use some kind of non-magnetic stainless steel
> > >
> > > Also this might be a moot point because I got a good strong signal by
> > > placing the watch on top of the guitar strings.  I did not
> > > have to restring
> > > the guitar.   The wall clock works even some inches away.
> > > You don't have
> > > to get really close to the magnets.   If you were building a
> > > sensor, just
> > > use a plain iron core and 1/4 pound of #40 wire
> > >
> > > >
> > > >
> > > --
> > >
> > > Chris Albertson
> > > Redondo Beach, California
> > > _______________________________________________
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> >
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>
>
>
> --
>
> Chris Albertson
> Redondo Beach, California
> _______________________________________________
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>



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