I had no idea that digital clocks time themselves by by measuring the mains frequency. And that this is an intended, albeit very minor, function of the power grid! It's amazing how things that provide only a tiny benefit to any individual but has an effect on such a massive scale that people actually sit down and spend time making it work.

"Over a decade old" is technically true, but probably an understatement, to me it looks like something from the 1980s or maybe 90s? Apparently it's old enough to not have "planned obsolescence" designed in...

Fascinating. I thought mains frequency was variable, which is why mains hum can be used to date recordings? It seems that there's some drift (why?) but they try to keep the average constant, over some window?

The article mentions the device prefers to use the mains frequency for timekeeping, using the crystal oscillator only as a fallback. I found this surprising, but I don't know much about either of those things.