Master Clock Keeps Time for All Other Clocks

accurate clock

[Brett] just finished construction and long-term testing of this extremely accurate timepiece. It keeps such great time by periodically syncing with the atomic clock in Mainflingen, Germany.

The core of the project is an ATMega328 which uses the new DCF77 library for decoding the signal broadcast by an atomic clock. The libraries written by Udo Klein significantly increase the noise tolerance of the device reading the signal, but they will not work with any project that use a resonator rather than a crystal.

In the event of a complete signal loss from the atomic clock, the micro driving the clock also has a backup crystal that can keep the clock running to an accuracy of within 1 second per day. The clock can drive slave clocks as well, using pulses with various timings depending on what [Brett] needs them to do. The display is no slouch either: six seven-segment displays show the time and an LCD panel reads out data about the clock. It even has chimes for the hour and quarter hour, and is full of many other features to boot!

One of the most annoying things about timekeeping is daylight savings time corrections, and this clock handles that with a manual switch. This can truly take care of all of your timekeeping needs!

THP Entry: Atomic Space Time

LCD featuring HaD logo

Accurate time is all around us. Streaming down from satellites thousands of miles in space, UTC time information is at all of our fingertips. You just have to know how to reach out and grab it. [hkdcsf] not only knows how to do this, he does it in style.

Tipping his hat into The Hackaday Prize contest, [hkdcsf]‘s atomic clock is masterfully crafted. Not only does it get time information from GPS satellites, it also has the ability to grab the infomation from the DCF77 transmitter. And if ever it’s in a position where neither signal can be found, an RTC crystal keeps the time and date accurate.

His design is based on a PIC18F25K20, and bristles with so many features that it might make you dizzy. So be warned – you might want to be in a seated position before taking a look at this project. [hkdcsf] does a great job at detailing exactly how his clock works, and his efforts to provide this level of detail will surely help other hackers to add similar features to their future projects.


SpaceWrencherThe project featured in this post is an entry in The Hackaday Prize. Build something awesome and win a trip to space or hundreds of other prizes.

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A weekend trip to verify general relativity

8 years ago, for the 100th anniversary of the theory of relativity [Tom] decided to test the general theory of relativity.

As he was going to Mt Rainier (5400ft high) with his children for the weekend, he brought in his van 3 cesium clocks while leaving other atomic clocks at his home for comparison. The theory behind the test is that if you’re are at higher altitudes, then your speed (in a galactic coordinate system) is higher than the one you’d have at sea level and therefore time would go “slower” than at lower altitudes.

[Tom] brought 400 pounds of batteries, 200 pounds of clocks and left his car turned on during his 2 days stay in the ‘Paradise Lodge’. He used 120V DC to AC converters and chose to bring 3 cesium clocks to have a triple redundant  setup. When he came back home, he had the good surprise of finding a time difference of 23ns. This is a great application for those rubidium sources you’ve been scavenging.

[Thanks Indyaner via Reddit]

Atomic skull clock reminds us we’re dying

atomic-skull-clock

Whether you like it or not, every second that passes brings you one step closer to your own demise. It’s not a comforting topic to dwell upon, but it’s reality. This art installation entitled ‘Memento Mori’ is a haunting reminder of just that. Even with all the advanced technology we have today, we still have absolutely no way of knowing just when our time will come.

[Martin] cast a real human skull, then added a 4 digit LED display that’s attached to a rubidium atomic clock (running a FE-5680A frequency standard). The display counts down a single second over and over, measured in millisecond-steps, from 1.000 to 0.001. He built a custom electronic circuit to convert the 10 MHz sine wave into a 1 kHz pulse signal, and used ATmega8 chips running an Arduino sketch to do the rest of the dirty work.

Watching the video after the break, with that smooth mysterious music in the background, one can’t help but ponder our mortality. On a personal note, this totally feels like something you’d find in a video game.

[Thanks Martin]

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DCF77 signal filtering and decoding

dcf77-filtering-and-decoding

[Udo] decided to build a clock using the DCF77 radio module seen above. This of course has been done before: the hardware draws a clock signal from the atomic clock in Braunschweig, Germany. So he grabbed a library for Arduino and got to work. But he was getting rather poor results and upon further investigation realized that the library had been written for 20 Hz modules and his operates at 300 Hz. This means better accuracy but the drawback is that the hardware is more susceptible to noise.

So began his journey to filter, process, and decode the DCF77 protocol. That link goes to the project overview. It will be in several parts all of which will be linked on that page. So far he has applied a low-pass filter and coded some exponential smoothing. He has yet to write the other four parts, but does mention that early testing shows that this technique will make the reception better than what is achieved with commercially available clocks. He was able to lock onto a signal that had more than 80% noise ratio. That’s impressive!

Just want to see a clock that uses a DCF77 module? Check out this PIC-based atomic clock.

Hackaday Links: June 12, 2012

Amazing 3D rendering in real-time

Ah, the 90s. A much simpler time when the presenters on Bad Influence! were amazed by the 3D rendering capabilities of the SGI Onyx RealityEngine2. This giant machine cost £250,000 back in the day, an amazing sum but then again we’re getting nostalgic for old SGI hardware.

Well, Mega is taken… let’s call it Grande

[John Park] needed to put something together for last month’s Maker Faire. A comically large, fully functional Arduino was the obvious choice. If you didn’t catch the demo last month, you can grab all the files over on Thingiverse.

Is that an atomic clock in your pocket or… oh, I see.

Here’s the world’s smallest atomic clock. It’s made for military hardware, so don’t expect this thing to show up at Sparkfun anytime soon; we can’t even fathom how much this thing actually costs. Still, it’ll be awesome when this technology trickles down to consumers in 10 or 20 years.

Converting a TRS-80 keyboard to USB

[Karl] is working on an awesome project – putting a Raspberry Pi inside an old TRS-80. The first part of the project – converting a TRS-80 keyboard to USB – is already complete. We can’t wait to see this build finished.

 A DIY Propeller dev board

Last week we complained about the dearth of builds using the Parallax Propeller. A few noble tinkerers answered our call and sent in a few awesome builds using this really unique micro. [Stefan]‘s Propeller One is the latest, and looking at the schematics it should be possible to etch a single-sided board for this project. Awesome work and thanks for giving us a weekend project, [Stefan].

How do atomic clocks work?

[Bill Hammack] aka [Engineerguy] is back again with another fantastic informational video. This time around he’s describing exactly how an atomic clock does what it does. He starts off with a great analogy of jello jiggling when poked. He explains how this is similar to the quartz crystal inside the clock oscillating due to the electrical “poke” we give it.  He goes on to explain how GPS satellites rely on this accuracy when determining physical locations on the ground.

As usual, [Bill] does a fantastic job of delivering the information quickly and packed full of detail, while still keeping it simple enough that even those unfamiliar with the technology can follow along.

[Read more...]

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