Radio Controlled Clock

[Mike Watterson]

The original idea was that your wrist would act somewhat as a "crystal oven", given the metal back and the tuning fork 32768 Hz crystal near the back and about 35 °C approx there from the 37 °C blood heat, so actually removing the watch each night would reduce the crystal temperature. I've no idea if that speeds up or slows the watch.

The 60KHz RF generation on an Apple phone sounds unlikely?

I've noticed that the big quartz wall clocks with a moving second hand mostly have much poorer battery life than the common small ones.

[Mark Hennessy]

The 60KHz RF generation on an Apple phone sounds unlikely?

https://apps.apple.com/us/app/clock-wave/id1073576068

Not tried it myself, but there are plenty of positive accounts, not just on the app store but on various technical forums.

It apparently works via the loudspeaker voice coil. Obviously the audio system doesn't go that high, so it relies on harmonics.

[Mike Watterson]

Ah, so there isn't an RF generator. Inductive coupling and harmonics from audio drive as it would need maybe 96 kHz DAC/Audio out.

[Radio Fixer]

Interesting post by Hamid: thanks.
I imagine the watches use the strap as an antenna: is this correct.

Gary