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Comment by riskable | Hacker News Reader

I want to see someone convert one of those cheap projection clocks like this: https://www.homedepot.com/p/La-Crosse-Technology-5-in-Color-...

The red projection is just the right brightness (at night) but it sucks that it's not wifi-enabled so you can't just get it to NTP sync (or hook up a GPS receiver). The projector part of the clock is a separate device that's attached to it via a ribbon cable. I would reverse engineer it myself but I haven't got the time.

Ideally, I'd want a matrix of LEDs projected on to the ceiling so I could get more info than just the time. Such clocks exist but they're super duper expensive! Example: https://buyfrixos.com/

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If you're looking for something low brightness, I made one: https://www.stavros.io/posts/i-made-another-little-bedside-c...

The one you linked claims to have "Atomic Time" which usually means syncing by radio from WWV/WWVB. I have several cheap wallclocks like this (though none with a projector) and they are always accurate with no noticeable drift AFAICT. Have you tried that particular one and found its accuracy wanting? I think, in principle at least, there should be less jitter in this method than using NTP over a computer network.

With a resolution of one second, I think most people would be hard pressed to distinguish between NTP and WWV/WWVB time keeping devices.

Right. WWVB clocks running off the 60KHz pretty much solve the clock problem in the US. All my clocks at home are basic LaCrosse analog clocks. They have the internal sensors needed to tell when each hand is straight up, so they can set themselves without user input. On power up, they step until the hands are straight up, then sync when they get an update. You have to set the time zone with a switch when installing. Only the four US time zones are available. Battery life is 1-2 years, which is pretty good for a device with a radio.

There are UK and Japan clocks that work similarly, but use national time sources. There are G-Shock watches which synchronize from multiple sources. While running on solar power. Those keep accurate time with no maintenance. That's an impressive achievement.

> WWVB clocks running off the 60KHz pretty much solve the clock problem in the US.

YMMV depending upon location. I've never gotten a WWVB clock to work in North Carolina. On the East Coast, the signal maybe sorta works for a few hours overnight:

https://tf.nist.gov/tf-cgi/wwvbmonitor_e.cgi

T̶h̶e̶y̶ ̶a̶l̶s̶o̶ ̶d̶o̶n̶'̶t̶ ̶t̶r̶a̶n̶s̶i̶t̶i̶o̶n̶ ̶D̶S̶T̶ ̶a̶u̶t̶o̶m̶a̶t̶i̶c̶a̶l̶l̶y̶,̶ ̶s̶o̶ ̶y̶o̶u̶'̶r̶e̶ ̶p̶u̶l̶l̶i̶n̶g̶ ̶t̶h̶e̶m̶ ̶o̶f̶f̶ ̶t̶h̶e̶ ̶w̶a̶l̶l̶ ̶t̶w̶i̶c̶e̶ ̶a̶ ̶y̶e̶a̶r̶ ̶u̶n̶l̶e̶s̶s̶ ̶y̶o̶u̶'̶r̶e̶ ̶i̶n̶ ̶o̶n̶e̶ ̶o̶f̶ ̶t̶h̶e̶ ̶r̶a̶r̶e̶ ̶U̶S̶ ̶l̶o̶c̶a̶t̶i̶o̶n̶s̶ ̶t̶h̶a̶t̶ ̶d̶o̶n̶'̶t̶ ̶a̶d̶h̶e̶r̶e̶ ̶t̶o̶ ̶t̶h̶e̶ ̶D̶S̶T̶ ̶s̶i̶l̶l̶i̶n̶e̶s̶s̶. Edit: My bad, they can switch in/out of DST automatically, at least when they can work at all.

I'm fairly certain the radio time signal has a mechanism to convey daylight savings, I've had alarm clocks that managed DST without any input.

> The DST status bits indicate United States daylight saving time rules.

https://en.wikipedia.org/wiki/WWVB

You're right. I was wrong about that, mostly because I've never had a WWVB clock work for me at all.

I have a few WWVB clocks. The ones that are on the north/south walls will never sync on their own, but east/west walls will sync just fine. I just take down the north/south clocks twice a year and lean them on a west facing wall and they'll sync overnight.

I think that most WWVB clocks just don't have the size to have an omni-directional antenna.

If I have to take the clock off the wall and move it outside, I may as well set it by hand. In any case, I've tried leaving one outside facing west and it still doesn't work. I've literally never had one of these clocks work from NC.

Meanwhile, the WiFi NTP clock I purchased just works, like I always hoped the WWVB clocks would have.

https://news.ycombinator.com/item?id=46948343

Radio clock (with reception) should be less jitter, but NTP measures round trip time, so you can estimate time in flight estimate; if your path is reasonably symetric, you could end up with less error.

I'm not sure how much it really matters though.

Some clocks also update over radio. Oregon Scientific used to make the best bedside atomic clock ever. Super simple, with the projector, was an atomic clock that updated automatically via radio and had a pleasant, crescendo alarm that would start off nice and get more aggressive. They don't make it anymore :/

Undermining the spirit of HN: By the time you’ve spent a few hours hacking away and bought any parts, that price is probably not too bad.

That's assuming you don't like hacking and would pay to not have to do it, which is generally not the case around here.

I’m think you can go further than that.

Days spent modifying cheap electronics is absolutely encouraged.

Buy the premade thing and hack something new.

Cheap electronics are just the feed stock, the basis function for your new creation. Why start with raw matter when you can get fully formed matter for less.

I disagree.

My most precious resource is free time. I never have anywhere near enough.

It is absolutely not worth $5 for me to spend another 15 minutes trying to find a cheaper price

+1 I have a couple of digital.clocks from Temu. They look nice but cannot keep the correct time. They slowly edge ahead and in a month they are about a minute ahead. It is annoying having to correct the clock and would be great if they time from WiFi connected source.

I love my WWV/WWVB clocks. It is nice never having to set them and they are all within a second of my NTP clocks.

Now if only I could turn off the clocks on my oven and microwave...

Depending on how dark your room is you might get by with an ordinary but bright LCD screen and a camera lens. There's a pretty common 240x240px, 1-inch square TFT display on amazon or other usual places you might start with.

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