What is it?

This item is an LED clock display that connects to the Internet via WiFi to obtain very accurate time using NTP. It has can display time with a granularity of a tenth of a second. Depending on your network quality the accuracy can be on the order of tens of milliseconds. The board is powered by USB-C. A button on the back will put the clock into setup mode, where it will advertise a WiFi network. You connect to that network and use a web browser to set the WiFi configuration and display options. Assuming your network can see the Internet, the clock should set itself on power-up within a few dozen seconds.

How good is it?

This clock should be considered to be about as good as a WWVB (so-called "atomic") clock. Its accuracy will be highly dependent on how good your connection to the NTP server is. Best case (good WiFi connectivity and a local stratum 1 server) you should find that it's within high single-digit milliseconds or so. Under ideal conditions, if you take a 120 Hz slow-motion video of this clock and one of my GPS clocks, you'll find the tenth-of-a-second digit on both will change in the same frame. If you have reasonable WiFi and are using the NTP pool, you might find it will differ by one frame or two. One advantage this clock has is that WWVB clocks generally do not get reception when the sun is out, while this clock polls at least twice an hour.

Why did you make it?

My GPS Clock is the inspiration for this item, but sometimes getting good Internet connectivity is easier than getting good GPS reception.

What it comes with

The clock optionally comes with a suitable USB-C power supply, but any available one should be suitable (the clock requires 5V @ 5W).

A 3D printed case (in black or white) is also available.