# Automatic/Quartz: Eco Drive - Sweep Second Hand?



## londonwatchlover (Dec 8, 2010)

I'm still learning so please take it easy 

So auto/mechanical watches have a sweeping second hand. Where does the eco-drive stand fit in this paradigm?

Do eco-drives also have sweeping second hand? I am a bit confused, they are quartz watches but with solar charging batteries? Whereas automatic watches rely on movement to wind?

Why do autos/mechanical watches have a sweeping second hand in any case?

Thanks all!


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## tixntox (Jul 17, 2009)

In simple terms, the sweep depends on how many "beats" per minute (or per second!) that the movement has. The higher the number of beats/sec, the smoother the sweep (very small fractions of a degree rotation/sec). Quartz are timed to move the stepper motor 6 degrees rotation (hence the one second jump of a quartz). Some electric watches have mind blowing numbers of movements per second and are therefore very accurate and have very smooth seconds hand sweeps. Quartz can be even more accurate as they can be timed to move the stepper motor on a certain "beat". There has been a post on how quartz watches work on the forum this week. Hope this helps. No doubt others will add their thought but that's how my "mechanical" brain sees it.

Mike


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## Andy the Squirrel (Aug 16, 2009)

Quartz watches advance the seconds hand once per second to conserve battery life. They could, if they wanted, move the seconds hand many times a second but it would deplete the battery faster. The new Bulova Precisionist does this (2 year from a lithium battery, compared with 10 years+ if the same lithium battery was powering a standard quartz movement)


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## DaveOS (May 9, 2010)

Bit off topic but I'd much rather have a smooth second hand sweep and change the battery more frequently.


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## hilly10 (Jul 19, 2009)

My Citizen Skyhawk Eco Drive moves like a quartz


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## clockworks (Apr 11, 2010)

Mechanical watches move the seconds hand between 5 and 10 times a second, depending on the design of the movement. Broadly speaking, the faster the beat, the better the real-world timekeeping.

I think that the only current movement with a truly sweeping seconds hand is the Seiko Spring Drive hybrid. This has a continuous drive - no stepping at all.

Since Bulova is owned by Citizen, I'd expect to see an ecodrive version of the Precisionist movement in the not too distant future. Maybe one that "sweeps" when exposed to light, but falls back to one second steps in the dark to conserve power.


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## harryblakes7 (Oct 1, 2010)

The Eco-driver has a translucent dial which allows light through it to the solar panel behind it, this then charges the capacitor which then drives the standard quartz movement, so basically it's a quartz watch which never needs a battery.

Some mechanical watches do have a seconds hand which "ticks" like a quartz but these are very rare...... Rolex "True-Beat" and some older wrist watches with a Duplex escapement.

Most mechanical watches would have a fairly jerky second hand movement as these watches gear train "start and stop" fairly violently due to the low beat rate ( usually 18,000 beats per hour ) and thickness of gears and inertia ( that's why most gears are stamped out to reduce weight ) but to make it smoother they use an extra large wheel to drive the very small wheel on the seconds hand to make this "starting & stopping" action smoother, this can usually be seen on the back of the movement as the wheel is much larger than a standard wheel.

Apologies if this has been discussed before........... :to_become_senile:


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## Andy the Squirrel (Aug 16, 2009)

Dave O said:


> Bit off topic but I'd much rather have a smooth second hand sweep and change the battery more frequently.


1960s/70s electric watch or bulova precisionist for you then!


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## Steve's Dad (Dec 19, 2007)

Andy the Squirrel said:


> Dave O said:
> 
> 
> > Bit off topic but I'd much rather have a smooth second hand sweep and change the battery more frequently.
> ...


Or a Seiko Springdrive.


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