DCF77 Powered Clock Is A Work of Art

December 6, 2013 by Mathieu Stephan 21 Comments

[Brett] just completed his DCF77 Master Bracket Clock, intended to be a backup to an old logic controlled clock he made. For our readers that don’t know, DCF77 is a German longwave time signal whose transmitter is located near Frankfurt (Germany). Every minute, the current date and time are sent on the 77.5kHz carrier signal.

The result, which you can see above, is made using an Ikea lantern, a skeleton clock, an ATmega328 (for Arduino compatibility), a voice recording playback IC (ISD1730), a cheap 20×4 LCD display, a DCF77 receiver module, and many LEDs. We’re pretty sure that it must have taken [Brett] quite a while to get such a nice looking clock. In case the clock loses power from the power supply, 3 AA cells provide battery backup. On the firmware side, making the platform Arduino-compatible allowed [Brett] to use its libraries so the coding was quickly done. Embedded after a break is a video of the final result.

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Making A UNIX Clock While Making A Few Mistakes Along The Way

November 30, 2013 by Mathieu Stephan 15 Comments

Sometimes the projects we think are easy to design are the ones on which we end up making the most mistakes. The UNIX clock that you see in the picture above is one of these projects. For our readers that don’t know it, UNIX time is the number of seconds since 00:00 on January 1st 1970. The clock that [James] designed is based on an Arduino Pro Mini board, an RTC chip to store the time, a custom made display board and two buttons to set the date/time.

One of the mistakes that [James] made was designing the boards on which will be soldered the seven-segment displays before actually choosing the ones he’ll use, as he was thinking they’d be all the same. The displays he ended up with had a different pitch and needed a different anode voltage, so he had to cut several traces on the PCBs and add another power supply. It also took [James] quite a while to remove the bits that his hackerspace’s laser didn’t cut through. We strongly advise a good look at his very detailed write-up if you are starting in the electronics world.

If you find this Unix time display too easy to read here’s one that’s a bit more of a challenge.

ATMega16 Hard Disk Clock

November 23, 2013 by James Hobson 14 Comments

[Martin Stromer] made this great looking Hard Disk Clock about 12 years ago, and finally decided to share it with the world. It’s been “ticking” ever since.

It’s a beautiful clock, and if you think the drive might look a bit odd, that’s probably because its well over 20 years old! We’re not too sure the capacity, but it couldn’t have been more than a few dozen megabytes.

To read the time, the platter rotates 30 degrees at once, per hour. The read-write head inches across the disc to display the minutes. Each of the black lines represents a quarter hour. The whole thing is controlled by an ATMega16, which maintains almost all of the original hardware. The blog post has a great write-up on how it all works.

Did we mention it’s also easy to set the time? Simply rotate the disc by hand and slide the read-write head into place, then press the reset button. Check out the clock in action after the break.

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Arduino Astronomic Clock Automates Lights

November 15, 2013 by Marsh 32 Comments

[Paulo’s] garden lights are probably a bit more accurately automated than anyone else’s on the block, because they use latitude and longitude clock to decide when to flip the switch. [Ed Note from the far future: this page no longer exists, but you can still read it on the Wayback Machine. The TimeLord library has also been superceded, so you’ll have some porting to do.]

Most commercial options (and hobbiest creations) rely on mechanical on/off timers that click on an off every day at the same time, or they use a photosensitive element to decide it’s dark enough. Neither is very accurate. One misplaced leaf obscuring your light-dependent resistor can turn things on unnecessarily, and considering the actual time of sunset fluctuates over the year, mechanical switches require constant adjustment.

[Paulo’s] solution addresses all of these problems by instead relying on an algorithm to calculate both sunrise and sunset times, explained here, combined with swiftek’s Timelord library for the Arduino. The build features 4 7-segment displays that cycle through indicating the current time, time of sunset and of sunrise. Inside is a RTC (real time clock) with battery backup for timekeeping along with an Omron 5V relay to drive the garden lamps themselves. This particular relay comes with a switch that can force the lights on, just in case.

Check out [Paulo’s] project blog for the full write-up, links to code and more details, then take a look at some other home automation projects, like the SMS-based heater controller or occupancy-controlled room lighting.

Fire Bell Wakes You For Work By Shaving Years Off Your Life

November 3, 2013 by Mike Szczys 38 Comments

If you suck at getting up in the morning [Jake Lee] has a solution that will make sure you don’t get fired from your job. Unfortunately it’s going to scare the life out of you — but maybe we’re just not hard enough sleepers to appreciate the value in an alarm clock that’s so horribly loud.

At first we wondered where he got the bell but it looks like you can buy one for about fifteen bucks. We’re not saying you should hide one of these under your best friend’s bed, but the cost of the bell does put it firmly in the worth-it-as-a-prank price range. [Jake] used rigid and flexible conduit to connect the bell to a power source, and the control panel shown on the left. He uses the LED backlight of the bedside alarm clock to drive the base of a transistor, switching a relay to trigger the bell. The big button on the grey box makes the wailing stop (seriously, cut your volume before you hit 0:30 in the clip below).

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Heathkit Clock Updated With A PIC32 And GPS

November 1, 2013 by Adam Fabio 46 Comments

One of [Bob’s] most treasured possessions is a Heathkit alarm clock he put together as a kid. Over the years he’s noticed a few problems with his clock. There isn’t a battery backup, so it resets when the power goes out. Setting the time and alarm is also a forward only affair – so stepping the clock back an hour for daylight savings time means holding down the buttons while the clock scrolls through 23 hours. [Bob] decided to modify his clock with a few modern parts. While the easiest method may have been to gut the clock, that wouldn’t preserve all those classic Heathkit parts. What [Bob] did in essence is to add a PIC32 co-processor to the system.

Like many clocks in the 70’s and 80’s, the Heathkit alarm clock was based upon the National Semiconductor MM5316 Digital Alarm Clock chip. The MM5316 operates at 8 – 22 volts, so it couldn’t directly interface with the 3.3V (5V tolerant) PIC32 I/O pins. On PIC’s the input side, [Bob] used a couple of analog multiplexer chips. The PIC can scan the individual elements of the clock’s display. On the PIC’s output side, he used a couple of analog switches to control the ‘Fast’, ‘Slow’, and ‘Display Alarm/Time’ buttons.

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An Overly-Complicated Logic Chip Clock

October 29, 2013 by Brian Benchoff 27 Comments

When a normal alarm clock just won’t do, the only option is to build your own, entirely out of discrete logic chips. [jvok] built this alarm clock for last year’s 7400 Logic Competition. In a desire to go against the grain a little bit, [jvok] decided to use 4000-series logic chips. It was allowed under the rules, and the result is a wonderful example of what can be done without a microcontroller.

Most clock projects we’ve seen use a single button to increase each digit. [jvok] wanted to do something unique, so he is able to set his clock with a ‘mode’ button that allows him to independently set the hours, minutes, and seconds. He’s only ever seen this method of setting a clock’s time used with microcontroller-based projects, and translating even that simple code into pure circuitry is quite impressive.

This clock also includes an alarm function, set by a bunch of DIP switches in binary coded decimal. It’s a great piece of work, and deserving of much more attention than it received during the Open Logic Competition.