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.
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, or even use Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for MakeCode, CircuitPython, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.