Re: Digital LCD watch accuracy tester

I am wearing a Casio radio watch that automatically syncs to DCF77

I also have a Rubidium 10 MHz reference generator from ebay.

I think maybe use a 10 MHz piezo mounted against the watch as detector? There are several piezo sensors for that frequency, From:

Or maybe you can just pick up the watch's 10 MHz oscillator with a small antenna close to the watch,

Check / try with your shortwave radio on SSB with local oscillator should hear a tone. Then build a small RF 10 Mhz tuned amplifer?

Or 32 kHz if that is the crystal.

True, you could try listening to the harmonics with a good radio too,

I also have a Rubidium 10 MHz reference generator from ebay.

ali, stripped out and saw it had a piezo strapped across 2 metal pins that the watch is held against. These seem to be designed for quartz analogue watches- the app detects the missing motor pulses to correct the time..( as opposed to 'pulling' the crystal like they did in the old days) In the box, the piezo is connected to an LM386 ( !) and a USB comms chip to send data to the app. I can play some more now.