On 24/03/2021 23:53, bert wrote:
In article , Dave W
writes
On Mon, 22 Mar 2021 19:41:54 +0000, Scott
wrote:
On Mon, 22 Mar 2021 19:17:19 +0000 (GMT), charles
wrote:
In article ,
Â* Scott wrote:

How does my car clock work?Â* It cannot be quartz or radio controlled
as it runs slightly fast.Â* It cannot be synchronous because the supply
is DC.Â* Is there any form of adjustment to get it to run to time?

quartz can run fast - or slow,

In what circumstances?Â* I thought it was supposed to be accurate to
one second in so many thousand years.Â* Can the crystal be replaced?

Accuracy is what you pay for. I have had a few £1 rubber watches off
ebay, which either gain or lose 1 minute a day. Probably factory
rejects. So I bought a dozen crystals of specified accuracy for under
£2 the lot, which when installed in the watches rendered them decent
timekeepers.

My Rolex actually gains slightly - well they are clockwork after all.

Officially certified Rolexes are usually only guaranteed to keep time to
-4+6 seconds a day. (I think there are some "special" ones guaranteed to
-2+2.)

--
Max Demian