DIY Laser Coil: Radio-Controlled Watch Signal Transmitter

Are you a proud owner of the Citizen Skyhawk radio-controlled watch? While it boasts exceptional features, some users may encounter limitations in regions where certain time signal radio waves aren't supported. There's an app that can mimic transmitting time signals. The idea behind it is to emit electromagnetic signals to the watch via the speaker. However, this software only supports the frequency of Japanese waves. When using it, you need to adjust your phone's timezone to Tokyo. Otherwise, your watch will lag behind by an hour.

Introducing the JJY Simulator app – a groundbreaking tool designed to emulate time signal transmissions effectively. 

By harnessing electromagnetic signals emitted via your smartphone's speaker, this innovative application bridges the gap for those unable to access specific radio wave frequencies. Notably, it focuses on supporting the Japanese wave frequency.

To maximize the app's functionality, it's imperative to align your device's timezone with Tokyo's. This step guarantees optimal performance, preventing any discrepancies in time synchronization.

Initially, users may attempt direct usage by placing their smartphone's speaker in proximity to the watch. However, to enhance signal strength, employing an external speaker or coil is recommended. For those with a DVD laser head, a simple modification involving a 3.5mm plug attachment to the dismantled focusing coil can create an efficient external radio wave transmitting coil. Encasing it in heat shrink tubing and bending it at a 90° angle ensures precision alignment with the watch's dial.

Evaluating its effectiveness reveals promising results. With the coil positioned within 1 cm of the watch's glass, signal strength consistently reaches 'H' (High), underscoring its reliability and efficiency.

Furthermore, to optimize performance, ensuring your device's timezone aligns with Tokyo's is paramount. This strategic adjustment guarantees seamless integration with the watch's Japanese wave frequency requirements.

Accompanying this guide are visuals depicting the app interface and the finished coil with the 3.5mm jack, providing a comprehensive understanding of the setup process.

In actual testing, the watch consistently showed a signal strength of 'H' (Strong).

In conclusion, while this solution serves as a fundamental tool, its practical implications extend beyond precise timekeeping. Whether for daily use or occasional checks of the watch's wave reception, the JJY Simulator app promises enhanced functionality and convenience.