I am living in a country where there is no DCF77 sender nearby for my European radio controlled wristwatch to get its time. This vintage Junghans Mega doesn’t have any buttons to set the time, so to bring it back to life, I built my own ‘transmitter’, taking the NTP time of a Raspberry Pi and generating a modulated signal via GPIO pins to then magnetically couple it into the watch ferrite.
This program is useful if you have a clock that otherwise does not get any reception. This magnetic coupling is very low power and only works over a few centimeters, but before running this program, make sure you follow your local laws with regard to restrictions on radio transmissions.
See the video below for a demonstration and head over to GitHub for the code and build instructions.
Do you have a radio enabled device (Ed: I have a Casio watch that uses US or Euro time broadcasts)? Let us know in the comments.
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