[time-nuts] 60hz disciplined watch

[Joseph M Gwinn]

time-nuts-bounces at febo.com wrote on 04/20/2011 10:38:41 AM:

> From:
> 
> cook michael <michael.cook at sfr.fr>
> 
> To:
> 
> time-nuts at febo.com
> 
> Date:
> 
> 04/20/2011 10:39 AM
> 
> Subject:
> 
> Re: [time-nuts] 60hz disciplined watch
> 
> Sent by:
> 
> time-nuts-bounces at febo.com
> 
> 
> 
> 
> Le 20/04/2011 16:17, John Ackermann N8UR a écrit :
> >
> > I wonder if it's smart enough to have a sanity check to determine 
> > whether the line frequency is 50 vs. 60 Hz?
> >
> > BTW -- I have an Ecodrive watch, but it's radio controlled (as well as 

> > solar charging), so haven't seen any reference to this setting method 
> > before.
> >
> > John
> > ----
> >
> > On 4/20/2011 10:13 AM, paul swed wrote:
> >> My bet would be flicker and divide by 120. Doesn't really matter. But 

> >> since
> >> these watches use the light to charge the battery, sensing the 
> >> frequency is
> >> a byproduct. Nice and simple.
> >>
> I don't buy it. Makes a nice urban myth though. Incandescent sources 
> don't flicker like fluorescent sources and the Skyhawk user manual does 
> not recommend charging in front of flouresecent tubes to 
> maintain accuracy.

There is plenty of 120 Hz (or 100 Hz) ripple on incandescent light.  No 
fluorescent lamps required.  It's easy to test the issue with a photodiode 
and a scope.

Joe