I am trying to find a bedroom clock that can be set by NTP. I have tried without success to find a product or a project that meets my requirement and was hoping that someone might know of one.

The clock MUST:

  • have automatic dimming based on ambient light.
  • remain visible at all times including at night (when it will be automatically dimmed)
  • have Wifi


  • be powered by micro-usb or USB-c


  • be a home assistant


  • alarm
  • battery back up (since the time is set by NTP)

I'd prefer just to buy a product but would be somewhat open to having to build it if:

  • complete instructions were available
  • it could be fully enclosed (to make it tidy)
  • I share your bewilderment that such a device does not exist. (Well, seem to exist.)
    – Pointy
    Commented Nov 10, 2023 at 0:49
  • Actually check out timemachinescorp.com for some that fit your (our) description. They're surprisingly expensive, which tells me there is no consumer market. I also found this clock on Etsy, which is cheaper and of course much much cooler.
    – Pointy
    Commented Nov 10, 2023 at 1:25

3 Answers 3


What you search for is named radio-controlled clocks (and watches). They (usually) use signal from special long wave radio station which transmit precise time.

You can see one in Germany which cover almost entire Europe (including UK) - DCF77.

If you live in USA you can use WWVB (which is shorwave station).

P.S. Here you can find the transmitters and areas also in China and Japan.

If you want DIY clock you can check here for USA, here for Germany, USA, etc.

If you want to create own clock which use NTP you can follow this manual. Schema is located here.

  • No, this is why I asked for NTP. I have nothing local like that. Commented Jul 4, 2023 at 23:16
  • @user3421823, I added DIY clock with NTP client, based on ESP32. Commented Jul 5, 2023 at 4:27
  • In the US the clock sync signal is unbelievably faint and terribly difficult for cheap clocks to pick up. The over-the-air mechanism is insane in a world where refrigerators and washing machines connect to the local wifi network.
    – Pointy
    Commented Nov 10, 2023 at 0:49

This isn't strictly what you asked for, but if you happen to be in the UK [& I think some parts of the EU have something similar] there's a national broadcast time signal, known as the Rugby Clock [though it's no longer broadcast from Rugby, the name has hung on.]
Its official name is Time from NPL [the National Physics Laboratory]

Here's a DIY Rugby Clock project & examples from a UK clockmaker, Creative Watch co [they also make radio-synchronised watches.]

No wi-fi needed, works anywhere in the country.

Of course, any DAB radio will be able to do the same, worldwide. Again, no wifi needed.
Amazon is full of clocks of varying spec, claiming to do just what you asked for - too many to hunt through for one with those exact features.

  • Yeah, this is why I asked for NTP. I have nothing local like that. Commented Jul 4, 2023 at 23:16

Why not just use a small cheap tablet with a clock app. I did just this, in the early days.

You can use Atomic Time - NTP Clock Sync to sync the clock with NTP.

And this (one of many) Clock for the Clock app

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