[time-nuts] Is a crystal likely to change frequency by 3% ?
tshoppa at gmail.com
Sat Sep 13 08:34:27 EDT 2014
On Sat, Sep 13, 2014 at 8:08 AM, Dr. David Kirkby (Kirkby Microwave Ltd) <
drkirkby at kirkbymicrowave.co.uk> wrote:
> So if it the mechanics skips a pulse, one really needs some method of
> measuring the position of the hands and recording that.
Better modern quartz movements, have circuitry in the pulse driver that
senses reluctance during the drive and will adjust the drive level down to
save battery power if mechanical drag is low, and when the drag level is
high (maybe fighting against gravity) even "re-do" the failed advances. The
mechanical WWVB movements also have sensors for calibrating position of
hour/minute/second hands (usually at a single fixed point on the dial).
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