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

quartz can run fast - or slow,

In what circumstances? I thought it was supposed to be accurate to
one second in so many thousand years. 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.
--
bert