Car clock

there may be a teeny adjustable tuning capacitor inside

No oscilloscope is good enough - you need a quality frequency counter

Even that isnt good enough.

Quite. Depends on how well made it is.

Car electric clocks were around before quartz too. Pure electric were pretty poor time keepers. Later on came clockwork ones, electrically wound. They were rather better. Many these days use the car radio RDS signal.

On your wrist in all weathers?

Bill

Don't you have any at home? They are normally minutes out each time you have to re-set for BST, etc.

Even then, a car is a pretty hostile place, because the temperature varies so much. Any oscillator needs a constant temperature for best results.

Only if you keep it on your wrist at night.

The clock on my car is most odd. Against the pips on FM radio, it always rolls over the minute bang on. But you can set the time to anything you fancy. The RDS signal then merely 'locking' it. Suppose it's a decent way of being able to use it anywhere. RDS might be a pain if you lived on the edge of two time zones. Luckily, once set correctly, it's very easy to alter the hour only for BST.

Not by itself but if you have an accurate reference frequency and access to the X amplifier (can you still do that with modern scopes?), a scope can be a very sensitive indicator.

Modern ones are.

That might be true of the components surrounding the crystal but crystals are cut along a plane of the crystal geometry such that temperature has a small effect on frequency change.

You will often hear of an AT cut:

That very much depends on how you wear a watch, I wear the same watch night and day, even in the bath and shower. Some people change their watch to suit their mode of dress.

Fredxx formulated on Tuesday :

..and they all change frequency a little, as they age and all need a frequency trimmer to enable them to be adjusted to an exact frequency. The trimming components are as critical as the crystal, if best accuracy is aimed for.

Dave Plowman (News) has brought this to us :

Mine does - always correct ;-)

My landline phone system maintains the time and date, for logging any calls and displays the time when 'parked'. It doesn't get used very much and I notice it drifts quite a lot. That syncs itself with any incoming or outgoing call.

Does it make any noise? Brian

Not a lot of detail, analogue or digital, and incidentally, I had a so called radio clock that in some places in the house ran fast since it lost lock to its signal which apparently came from Germany. Brian

Yes, it can be

It simply needs a better internal oscillator, temerature compensated than the one it is testing and enough electronics to display very small differences. and a stable environment and regular calibration.

Needless to say, they are not cheap.

NEAR ENOUGH IS GOOD ENOUGH YOU HAVE TO RESET IT TWICE A YEAR ANYWAY

I, too, have a clock, bought in Lidl, which receives the German time service. With my wristwatch I can choose which time service I want to receive. The outdoor one on our Village Hall also uses the German time service.