MSF

3 Articles

Keeping Clocks On Time, The Swiss Way

September 17, 2019 by 31 Comments

Could there be a worse fate for a guy with a Swiss accent than to be subjected to a clock that’s seconds or even – horrors! – minutes off the correct time? Indeed not, which is why [The Guy With the Swiss Accent] went to great lengths to keep his IKEA radio-controlled clock on track.

For those who haven’t seen any of [Andreas Spiess]’ YouTube videos, you’ll know that he pokes a bit of fun at Swiss stereotypes such as precision and punctuality. But really, having a clock that’s supposed to synchronize to one of the many longwave radio atomic clocks sprinkled around the globe and yet fails to do so is irksome to even the least chrono-obsessive personality. His IKEA clock is supposed to read signals from station DCF77 in Germany, but even the sensitive receivers in such clocks can be defeated by subterranean locales such as [Andreas]’ shop. His solution was to provide a local version of DCF77 using a Raspberry Pi and code that sends modulated time signals to a GPIO pin. The pin is connected to a ferrite rod antenna, which of course means that the Pi is being turned into a radio transmitter and hence is probably violating the law. But as [Andreas] points out, if the power is kept low enough, the emissions will only ever be received by nearby clocks.

With his clock now safely synced to an NTP server via the tiny radio station, [Andreas] can get back to work on his other projects, such as work-hardening copper wire for antennas with a Harley, or a nuclear apocalypse-Tweeting Geiger counter.

Continue reading “Keeping Clocks On Time, The Swiss Way” →

No Signal For Your Radio-Controlled Watch? Just Make Your Own Transmitter

September 10, 2018 by 36 Comments

You can win any argument about the time when you have a radio controlled watch. Or, at least, you can if there’s any signal. [Henner Zeller] lives in a place where there is no reception of the DCF77 signal that his European wristwatch expects to receive. Consequently, he decided to make his own tiny transmitter, which emulates the DCF77 signal and allows the watch to synchronise.

A Raspberry Pi Zero W is the heart of the transmitter, and [Henner] manages to coax it into generating 77500.003Hz on a GPIO pin – close enough to the 77.5kHz carrier that DCF77 uses. The signal is AM, and transmits one bit/s, repeating every minute. A second GPIO performs the required attenuation, and a few loops of wire are sufficient for an antenna which only needs to work over a few inches. The Raspberry Pi syncs with NTP Stratum 1 servers, which gives the system time an accuracy of about ±50ms. The whole thing sits in a slick 3D printed case, which provides a stand for the watch to rest on at night; this means that every morning it’s synchronised and ready to go.

[Henner] also kindly took the time to implement the protocols for WWVB (US), MSF (UK) and JJY (Japan). This might be just as well, given that we recently wrote about the possibility of WWVB being switched off. Be sure to check the rules in your area before giving this a try.

We’ve seen WWVB emulators before, like this ATtiny45 build, but we love that this solution is an easy command line tool which supports many geographical locations.

Old LED Light Bulbs Give Up Filaments For Spider Web Clock

August 1, 2018 by 41 Comments

We love it when something common gets put to a new and unusual use, especially when it’s one of those, “Why didn’t I think of that?” situations. This digital clock with a suspended display is just such a thing.

The common items in this case were “filaments” from LED light bulbs, those meant to mimic the look of clear-glass incandescent light bulbs. [Andypugh] had been looking at them with interest for a while, and realized they were perfect as the segments for a large digital clock. The frame of the clock was formed from bent brass U-channel and mounted to an oak base via turned stanchions. The seven-segment displays were laid out in the frame and the common anodes of the LED filaments were connected together, with the cathode for each connected to a very fine wire. Each wire was directed through a random hole in the frame and channeled down into the base, to be hooked to one of the four DS8880 VFD driver chips. The anode wires form a lacy filigree behind the segments, which catch the light and make then look a little like a spider’s web. It looks great, but nicht für der gefingerpoken – the frame is at 80 VDC to drive the LED segments. The clock is synced to the UK atomic clock with a 60-kHz radio link; see the long, painful sync process in the video below.

We like the open frame look, which we’ve seen before with an equally dangerous sculptural nixie clock. And this gives us some ideas for what to do with those filament LEDs other than turning them back into a light bulb. And if [Andy] sounds familiar, it could be because he’s appeared here before. First of all resurrecting the parts bin for an entire classic motorcycle marque, and then as the designer of SMIDSY, a robot competitor in the first incarnation of the UK Robot Wars series.

Continue reading “Old LED Light Bulbs Give Up Filaments For Spider Web Clock” →