[ilyt]

Sooooo how much power does that clock use ?

Because simplest one would be:

* a cheapo chinese subwoofer amplifier * 12V wall-wart to power it * a quartz-stabilized 50Hz generator (soooo an arduino, with DAC, even simple R2R + some filtering). * transformer fitting subwoofer amp output voltage. Measure amp output voltage at near-max, connect amplifier to secondary and tweak the "volume" till it is right.

Sub amp is like $5, $3 for cheapest arduino clone, probably like $2 for transformer, and few bucks in proto board and other components

If you want to overcomplicate it you could put rPi into it and sync the 50Hz clock to NTP

[amluto]

> If you want to overcomplicate it you could put rPi into it and sync the 50Hz clock to NTP

That’s ridiculous! Buy a little GPS-disciplined oscillator and either scale the PPS output up to 50Hz or use a PLL to derive 50Hz from the oscillator output :)

[BenjiWiebe]

Just use a pll to derive 50 from 60. Problem solved.

[zbrozek]

The GPSDO will also give you correct time of day and unwavering frequency. I used to have one set up at home to feed my test equipment a 10 MHz reference.

[ilyt]

If you're powering 50/60Hz clock you won't be setting time remotely on that easily

[chromoblob]

But how do GPSDO work? Is GPSDO susceptible to metastability?

[zbrozek]

GPS is a system for distributing time first and a means of computing position second.

A GPSDO is typically a PLL that uses the recovered timebase as a reference input and will have an incredibly slow loop filter. It can be outrageously highly damped and stable.

Such clocks are the basis of the cell network and have made doing client handoff between towers almost easy. The hard part is operating through GPS denial (mostly due to weather).

[seabass-labrax]

Would you mind revealing where you would go to for a power transformer that cheap? Clearly they must exist, as a full AC/DC adapter costs barely more than that, but eBay is wont to give me listings for merchandise of a certain animated TV series...

[ilyt]

Aliexpress would be my first bet. Random used junk second

https://www.aliexpress.com/w/wholesale-12V-220v-transformer....

[coryrc]

I've literally used an audio amplifier to directly create 240V 50Hz in a professional capacity so your idea is completely reasonable.

[ilyt]

Yeah I have prototype (working, sans transformer) somewhere on the pile of shame.