[time-nuts] Is a crystal likely to change frequency by 3% ?

Alexander Pummer alexpcs at ieee.org
Fri Sep 12 20:23:15 EDT 2014

just open the box, look for the wires which going to the magnet which 
drives the minute hand and measure the period time -- not the frequency, 
it is to low
yes analog quarz clock slows down as the battery get old,  you will be 
surprised, that the driver pulse's period time dos not change, but 
sometimes the divider chain or the mechanic skips a pulse, as the 
battery voltage drops further suddenly the clock mechanic or the 
electronic will stop working, takes less current so the battery recovers 
a bit, because the magnet did not used power for a while, and will run 
again for a while, the pause between two run time will be larger and 
larger so the clock looks like going slower

On 9/12/2014 3:52 PM, Dr. David Kirkby (Kirkby Microwave Ltd) wrote:
> Dr David Kirkby
> Managing Director
> Kirkby Microwave Ltd
> Registered office: Stokes Hall Lodge, Burnham Rd, Chelmsford, Essex, CM3
> 6DT, United Kingdom
> Registered in England and Wales as company number 08914892
> http://www.kirkbymicrowave.co.uk/
> Tel 07910 441670 / +44 7910 441670 (0900-2100 GMT)
> On 12 Sep 2014 12:18, "Bob Camp" <kb8tq at n1k.org> wrote:
>> Hi
> Hi,
>> If this is an RTC, it’s probably running off of a battery when the
> machine is powered down. It is far more likely that the oscillator is
> dropping out (stopping) rather than shifting frequency.
> Good point,  I never thought of that. I have however noticed that analogue
> quartz clocks slow as the battery goes flat. But maybe too they stop and
> start. It would make an interesting experiment to check it, but one would
> need some method of logging the time from the hands.  Conceptually that is
> not difficult,  but it needs more work than I want to do. One could do it
> with a video camera and a fair bit of work writing the software. Probably
> easier is logging battery voltage and current as that should show if it
> starts and stops.
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