Digital Clock Without Electricity or Moving Parts

NerdMachine writes "Throw away those slide rules and embrace the digital age. The Digital Sundial is a 10 year old invention on display in Sundial Park (Genk, Belgium), Deutsches Museum (Munich Germany), Kölnisches Stadtmuseum (Cologne, Germany), and Martha's Vineyard, USA. You need to pivot it to adjust daylight savings time. If you can't visit one of these, Digital Sundials International can sell you one for US$12,000+, or you can buy a pocket version for under US$100 for that special nerd in your life."

Comments

I cringe

[TheRoachMan]

I cringe at the sight of that Belgian website about the sundial park in Genk. Awful awful awful. I'm ashamed for my country.

Globe as sundial

[SiliconEntity]

I read an article in an old Scientific American about an especially simple sundial: mount a globe of the Earth outside, orienting it to be exactly parallel to the real Earth. That means pointing the north pole of the globe at the North Star, and rotating it so that your current meridian of longitude runs across the top. This will put your current location exactly at the top of the globe.

The cool thing is that sunlight will now fall on the globe in exactly the way it falls on the Earth (during the day, that is). You can see the day-night terminator and it will be the same as the terminator on the actual Earth. You can see which polar regions are getting 24 hour sunlight or night. You can tell whether it is day or night anywhere on Earth, and even estimate what time it is there.

It sounded pretty cool although I never bothered to try to set one up. You'd need some kind of waterproof globe that wouldn't fade in the sunlight. Probably there are some like this on public display somewhere.

I have the small one

[Anonymous Coward]

I bought the small 100$ version as a christmas gift. It's a very neat little thing, it's about three inches in diameter, and the results are impressive, but require bright, direct sunlight.

I'd recommend it for a gift for anyone who likes trinkets based on science, this is a novel implementation of a simple principle.

If I were to change anythign about it, i'd make it bigger. I don't know why the disc isn't 5...6 inches in diameter. It would be much more impressive.

Internet Time

[wwwillem]

Would be cool to make one of these that shows Internet Time. You remember, that dot-com time invention from Swatch to have time-zone crossing con-calls at @526 and everybody would then know when that was. For those who missed that, Swatch wanted to cut 24 hours into thousand pieces, so one unit of Internet Time (called a beat) is app. 1.5 minute, which is accurate enough for things like the start of a meeting.

The headache will be of course that sundials are by nature giving time in "local time" and need a correction to display "standard time". This problem would be agrevated when the dial has to display Internet Time, which can only be overcome to build custom sundials for every longitude on earth. This sounds bad, but sundials are anyway normally custom made, so maybe this isn't too bad. Probably the biggest obstacle is that now already, 5 years after the invention, nobody remembers what internet time was. Oh well.....

A deserving patent

[Cardbox]

This design was turned up as "prior art" when I was drawing up my own patent for moire-based time indication. It was sufficiently offtopic not to be relevant, but it was rather a nice idea so it's good to see it being implemented. It also sets a useful pricepoint for my own design...
Yes, it would be cool to display the date but there are a couple of problems.

1. When you're considering time, the sun moves round and round (forever westwards), so one position corresponds to one time, but when you're looking at dates, it oscillates (between north and south), so any date indication will be ambiguous between November and January, October and February, September and March...
2. Near the solstices the noon sun moves very very slowly, so the degree of amplification of motion required would be enormous and you'd run into diffraction problems.

Re:No Electricity?

[dschuetz]

1) Make holograms of the digits of the time in question (lots of holograms).
2) Take the holograms and cut them into strips.
3) Take some of the strips and glue them back to make one hologram

I don't think it uses holograms. It's more like a series of carefully-arranged slits, with light coming in from any given angle only making it through the gauntlet in a single path, while light form a different angle hits a different path. Theoretically *like* a hologram, but simulated by the masks over a depth somewhat greater than a single sheet of film.

On the other hand, I'd wondered *years* ago whether a digital sundial could be easily made from a simple hologram. No need to cut into strips -- any hologram already gives different images depending on the angle you look at it from. Generally, you see this as you walk around a hologram (like the novelty ones where someone blows you a kiss). Only instead of you walking, if you move the light source, the same animation plays out. Just build a multi-image hologram of all sorts of clock images, and as the light source moves, you'll see the clock animate forwards. It could even be an analog clock -- any picture would work.

If you account for varying altitudes of the sun, you might even be able to get the month displayed (though it'd probably have to show two dates at once, letting the user decide whether it's, say, December 1 or January 9 (each being about 20 days away from the solstice).