Just another electronics blog describes an interesting watch build with a novel display:

Ok ok ok, this is not a Nixie, it’s a Panaplex watch, but that sounds so much less fun. They work like nixies, but they are flat and often 7 segment displays, somewhat common in alarm clocks and tech gear. I got a few of them from a friend and compared to nixies, they are rather small and flat. So why not make a wristwatch with them!

Like nixies, panaplex displays require a high voltage to operate, around 200V. Which, on a wristwatch is a little challenging. I also wanted this to be a somewhat usable watch, unlike some of the nixie watches that, while cool, look quite cumbersome to wear due to their size.

This display is the ZM1570, which according to the datasheet, is similar to the ZM1550 but a little radioactive, fun!

I made a Numitron clock before using the STM32F042, which is a small ARM M0 micro with USB support. For that numitron clock I added a 12Mhz external crystal to keep time and to have an accurate USB clock. I decided to do the same for this clock. Looking at the power used by the display, I decided a low power MCU like the STM32L series was perhaps not needed and I still had some F042’s.

This turned out to be a mistake…

Read more in the post here.