3 ms·

Edit: I was wrong! original post below: > Battery-backed self-setting “atomic” clocks that get their updates via the cosmic ether have been a thing for years a

Edit: I was wrong! original post below: > Battery-backed self-setting “atomic” clocks that get their updates via the cosmic ether have been a thing for years and get me most of the way there, but damned if I could find one with a red seven-segment display that I liked (maybe someone else’s search kung-fu is better than mine?) I found this with ~5 minutes of searching. I think it meets your critera: https://www.amazon.com/Sharp-Digital-Alarm-AccuSet-Automatic/dp/B089ZMSR39 https://www.amazon.com/Sharp-Digital-Alarm-AccuSet-Automatic... (Regardless, cool project! I think yours still looks better than this one)

Jtsummers 2mo ago
The clock you've linked is not an atomic clock. It has a pre-programmed clock with a battery keeping it going. If that battery dies, you still have to set the time manually.
- craftkiller 2mo ago
  Oh you're right! I was tricked by "AccuSet technology automatically sets the correct time when plugged in. No programming, no confusing buttons"
  - martheen 2mo ago
    I read up the manual before realizing the vaunted tech is simply a battery backup and setting the clock in the factory.