clock

590 Articles

Oscillator Needs Fine-Tuning

November 3, 2024 by 23 Comments

Since their invention more than a century ago, crystal oscillators have been foundational to electronic design. They allow for precise timekeeping for the clocks in computers as well as on our wrists, and can do it extremely accurately and inexpensively to boot. They aren’t without their downsides though; a quartz watch might lose or gain a few seconds a month due to variations in temperature and other non-ideal environmental situations, but for working in the world of high-frequency circuits this error is unacceptable. For that you might reach for something like an oven oscillator, a circuit with a temperature controlled chamber able to keep incredibly precise time.

[IMSAI Guy] found this 10 MHz oven oscillator on a site selling bulk electronics at bargain basement prices. But as is unsurprising for anyone who’s used a site like this to get cheap circuits, it didn’t quite hit its advertised frequency of 10.000000 MHz. The circuit design is capable of this amount of accuracy and precision, though, thanks to some cleverly-designed voltage dividers and filtering. One of those voltage dividers allows a potentiometer to control a very narrow range of output frequencies, and from the factory it was outputting between 9.999981 and 9.9999996 MHz. To get it to actually output a 10 MHz wave with eight significant digits of accuracy, a pull-up resistor on the voltage divider needed to be swapped out.

While this was a fairly simple fix, one might wonder how an off-the-shelf component like this would miss the mark in such an obvious way but still go into production. But that’s one of life’s great mysteries and also the fun of sourcing components like this. In this case, the oven oscillator was less than $10. But these circuits aren’t always as good of a deal as they seem.

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Geochron world time clock

Geochron: Another Time, Another Timeless Tale

October 26, 2024 by 10 Comments

The Geochron World Time Indicator is a clock that doubles as a live map of where the sun is shining on the Earth. Back in its day, it was a cult piece that some have dubbed the “Rolex on the wall.” Wired’s recent coverage of the clock reminded us of just how cool it is on the inside. And to dig in, we like [Attoparsec]’s restoration project on his own mid-1980s Geochron, lovingly fixing up a clock he picked up online.

[Attoparsec]’s recent restoration shares insights into the clock’s fascinating mechanics. Using a synchronous motor, transparent slides, and a lighted platen, the Geochron works like a glorified slide projector, displaying the analemma—a figure-eight pattern that tracks the sun’s position over the year.

But if you’re looking for a digital version, way back in 2011 we showcased [Justin]’s LED hack of FlorinC’s “Wise Clock”, which ingeniously emulated the Geochron’s day-night pattern using RGB LEDs, swapping out the faceplate for a world map printed on vellum. That’s probably a much more reasonable way to go these days. Why haven’t we seen more remakes of these?

The 1983 Clock Four Decades In The Making

October 21, 2024 by 13 Comments

In 1983, a 14-year-old [Will] saw an LED clock in The Sharper Image store. At $250, it stayed in the store. That was a lot of money back then, especially for most teenagers. But [Will] didn’t forget. After high school, he and a friend planned to build one from scratch. They worked out how they would do it and did a little prototyping, but never really finished. Well, they never really finished at the time. Because 33 years later, [Will] decided to finally put it together. Check it out in the video below.

[Will’s] learned a lot since his original design, plus we have tech today that would have seemed like magic in the late 1980s. But he wanted to stay true to the original design, so there’s no microcontroller or smart LEDs. Just binary counters and a lot of LEDs. There’s even a 555 doing duty as a reset timer.

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Recreating A Popular Faux-Nixie Clock

September 13, 2024 by 15 Comments

There’s a good chance you’ve seen “Nixie clocks” on the Internet that replace the classic cold cathode tubes with similarly sized LCD panels. The hook is that the LCDs can show pictures and animations of Nixie tubes — or pretty much anything else for that matter — to recreate the look of the real thing, while being far cheaper and easier to produce. It’s a hack for sure, and that’s the way we like it.

[Trung Tran] liked the idea, but didn’t just want to buy a turn-key clock. So he’s decided to build his own version based on the ESP32-S3. The WiFi-enabled microcontroller syncs up to the latest time via NTP, then uses a PCF8563 real-time clock (RTC) module to keep from drifting too far off the mark. The six displays, which plug into the custom PCB backplane, can then show the appropriate digits for the time. Since they’re showing image files, you can use any sort of font or style you wish. Or you could show something else entirely — the demo video below shows off each panel running the Matrix “digital rain” effect.

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Globe-Shaped World Clock Is A 3D-Printed Mechanical Marvel

August 12, 2024 by 5 Comments

Time zones are a complicated but necessary evil. Humans like the numbers on the clock to vaguely match up with what the sun is doing in the sky outside. To that end, different places in the world keep different time. If you want to keep track of them in a very pretty fashion, you might consider building a fancy and beautiful World Clock like [Karikuri] did. 

The design is based around a globe motif, mimicking the world itself. Only, on the surface of the globe, there are clock faces instead of individual countries. Each clock runs to its own time, directed by a complicated assemblage of 3D-printed gears. Mechanical drive is sent to the globe from a power base, which itself carries a mechanical seven-segment display. This too can display the time for different regions by using the controls below. It’s also useful for setting the clock to the correct time.

It’s a little difficult to follow the build if you don’t speak Japanese. However, quality subtitles are available in English if you choose to enable them.

We’ve seen [Karikuri’s] work before. We’ve also featured a great many world clocks over the years, including this particularly beautiful example that tracks night and day. Just don’t expect it to keep track of moon time. Video after the break.

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A Lenticular Clock Spells Out The Hours

July 24, 2024 by 1 Comment

So many are the clock projects which cross the Hackaday threshold, that it’s very rare indeed to see something that hasn’t already been done. We think we’ve not seen a lenticular clock before though, and we’re thus impressed by this one produced by [Moritz Sivers].

You may well be familiar with lenticular images from toys and novelties, an animation is sliced into lines and placed behind an array of multi-faceted linear lenses. It gives the effect of movement as from different viewing angles a different frame of the animation is perceived. In this clock the animation is replaced by the clock digits, and by rotating the whole with a servo driven by an ESP8266 microcontroller it can display different digits to the viewer. The write-up and the video below are of value both for the clock itself and the description of how these animations are produced. The clock itself doesn’t sacrifice usability for all its novelty, and we can see this technique might find a place in other projects requiring custom displays.

The lenticular lenses used here are off the shelf, but if you are of an adventurous mind, you could try printing some of your own.

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Single-Stepping The 6502 Processor

July 18, 2024 by 19 Comments

Although marketing folk and laypeople may credit [Steve Jobs] as the man behind the success of Apple, those in the tech world know the real truth that without [Steve Wozniak] nothing would have ever gotten off the ground during the early days of the computer company. As an exhibit of his deep knowledge of the machines he was building, take a look at this recreation of a circuit by [Anders] which allows the 6502 processor to step through instructions one at a time, originally designed by [Woz] himself, even though there are still myths floating around the Internet that this type of circuit can’t work.

Like a lot of Internet myths, though, there’s a kernel of truth at the middle. The original 6502 from the mid-70s had dynamic registers, meaning they would lose their values if the chip was run below a critical clock speed. Since single-stepping the processor is much lower than this speed, it seems logical that this might corrupt the data in the registers. But if the clock is maintained to the registers the processor can be halted after each instruction, allowing even the original 6502 to go through its instructions one at a time.

[Anders]’s project sets up this circuit originally laid out by [Steve Wozniak] but updates it a bit for the modern times. Since the technology of the era would have been TTL, modern CMOS logic requires pull-up resistors to keep any inputs from floating. The key design of the original circuit is a set of flip-flops which latch the information on the data bus, and a switch that can be pressed to let the processor grab its next instruction, as well as a set of LEDs that allow the user to see the value on the data bus directly.

Of course, a computer processor of this era would be at a major handicap without a way to debug code that it was running, so there are even dedicated pins that allow this functionality to occur. Perhaps the Internet myth is a bit overblown for that reason alone, but [Anders] is no stranger to the 6502 and has developed many other projects that demonstrate his mastery of the platform.

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