Hodinky Casio GW-7900B-1ER

Full-Auto Illuminator model with solar power and radio-controlled timekeeping. The watch automatically turns the electroluminescent backlight off when ambient light is sufficient and enables it in low-light conditions. It uses a solar cell for operation and receives DCF/MSF/WWVB/JJY/BPC radio signals to maintain accurate local time, including automatic changes for daylight saving in many regions. The display also provides moon phase and tide graph information based on the selected latitude and longitude. Durable construction includes shock resistance, mineral glass and a resin case and band. Additional features include stopwatch and countdown timer, five daily alarms with snooze, button tone on/off, automatic calendar, 12/24-hour display, battery level indicator and water resistance to 20 bar (200 metres).

Advantages

The combination of solar power and radio signal reception ensures continuous, low-maintenance operation with highly accurate timekeeping. Shock-resistant design, mineral glass and a flexible resin band provide durable everyday wear. Moon data and tide graph displays offer relevant information for outdoor and marine activities. Multiple alarms, a snooze function and a long countdown timer support daily scheduling and training needs. Clear battery level indication and selectable button tones add practical convenience.

Key specifications

How to use

Set the watch to the local time zone and allow it to receive the appropriate radio signal for automatic time adjustment. Charge the watch through exposure to light; the solar cell stores energy for operation. Use the mode button to switch between time, world time, stopwatch, timer and alarm functions. Configure alarms and countdown timers using the function buttons; enable or disable button tones as needed. For moon and tide displays, enter the correct latitude and longitude and, if required, adjust the lunitidal interval to match local tide behaviour.

Recommendations

To maintain optimal performance, expose the watch regularly to light for solar charging, avoid strong impacts despite its shock resistance, and rinse with fresh water after exposure to salt water. Periodically check the battery level indicator and verify radio reception when traveling between regions to ensure correct time settings.