Not long ago I stumbled upon a batch of vintage HP 5082-7356 displays. Those magnificent devices from the 80-ties , encased in glass - ceramic cases with built-in decoders deserved to be used again , so I built a watch with them.
The displays require a lot of power . Even when dark , the driver chip in each display consumes almost 0.5W . To keep with it the watch uses a LiFePo cell ( the size of AAA battery , housed in the round part of the watch ) and the high efficiency DC-DC converter. The heart of the watch is the STM32F051 MCU , used both as the RTC and as the display controller.
The case of the watch was milled from the block of aluminum and then anodized black .
The video of the completed watch can be found here :