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654 Articles

A Glorious Mechanical Seven Segment Display

April 15, 2012 by 36 Comments

If you’ve ever wondered why you’ve never seen a mechanical seven-segment display, now you know. They’re fairly complicated and most likely absurdly expensive, especially when a few light bulbs or LEDs would do the same job equally well. This didn’t stop [kiu] from completing his mechanical seven-segment clock he calls SevenBlocks, and for that we are thankful.

Each of the 28 segments in [kiu]’s clock is made of three layers of acrylic and a short section of a rack gear. Unlike every seven-segment display you’ve ever seen, tiny hobby servos provide the indication for each segment. For the electronics, An ATMega8 is used for the brains of the outfit with a 74HC595 shift register to expand the number of I/O lines. A DS1307 RTC module provides accurate timekeeping, and the dozens of servo outputs visible in the ‘guts shot’ makes you realize why you’ve never seen a mechanical seven segment display before – they’re really friggin’ complex.

If you want to build your own mechanical seven-segment clock, [kiu] put all the files up on Github. Everything is there, from the .DXF files ready to feed to a laser cutter to the schematic and board files for each of the three PCBs. A video showing this clock in action is sort of necessary, so you can check that out after the break.

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Quieting A Pendulum Clock Every Night

April 1, 2012 by 19 Comments

[Vinnie] has a wonderful old clock from his grandmother; it’s an exquisite antique with a real mechanical movement and a charming set of bells that ring every hour. Unfortunately, those chimes are a bit of a disturbance to neighbors at 2 o’clock in the morning. Previously, [Vinnie] had been stopping the clock every evening, and hoped he would remember to start the pendulum in motion 12 hours later. This was a chore, so he decided to automate the process.

The build is simple and clever; a small stepper motor is mounted in the clock just underneath the pendulum. Every 12 hours, the stepper motor moves a lever and slowly stops the pendulum over the course of a dozen or so seconds, silencing the clock movement. Twelve hours later, the motor turns again setting the pendulum in motion.

The parts count for this build is very low – basically just an ATmega88, a Darlington array to drive the stepper, and a 32.768kHz crystal. We can think of a few friends and relatives with loud clocks in their house, so we might have to build a few of these to give away.

Take a look at the demo video after the break to see how [Vinnie] stops his grandmother’s clock every night.

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Rolling Digit Clock Is A Wonderful Piece Of Engineering

March 1, 2012 by 16 Comments

A long time ago and on a scrounging trip he barely remembers, [Victor] bought a quartet of digits from an old Dutch Railways clock. These antique displays used a strip of plastic coated cloth that rolls around itself with the help of a motor to display the digits 0 through 9. It’s been many years, but [Victor] finally got around to building a clock out of these single digit displays and we’re loving the results.

Because these displays were manufactured in a time when mechanical devices were king, [Victor] had to slightly modify each digit so they could display numbers with the help of a continuous rotation servo. The four servos are controlled by an Arduino – each digit changing one at a time to reduce current consumption – and a magnet and reed switch was added to each digit so the numbers could be repeatedly displayed.

Before [Victor] replaced the plastic servo gears with metal cogs, the clock was quite noisy. He’s since put each digit underneath a bell jar (actually a vase turned upside down), and we’ve got to say that [Victor] has a nice clock on his hands. Check out the videos of the clock changing digits to display the time after the break.

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Tutorial: Build A Manifold Clock For $10

January 25, 2012 by 35 Comments

Every once in a while, the Hack a Day tip line gets a submission that is cool, but screams to be built in a few hours, possibly while consuming adult beverages. When [Shay] and [Ben] sent in their Manifold Clock Kickstarter, I knew what I had to do. To make a long story short, there’s a manifold clock hanging on my wall right now. Check out my manifold clock how-to guide after the break.

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Oscilloscope Clock Made Possible By Dumpster Diving

January 12, 2012 by 17 Comments

We see people driving around the night before trash collection and reclaiming items doomed to the land fill (or on their way to recycling… who knows). We’re beginning to think we need to join those ranks. Case in point is this vintage oscilloscope which [Bob Alexander] plucked from the curb in the nick of time. Here’s the kicker, when he got it home he found it still worked! He couldn’t let this opportunity go to waste, so he figured out how to turn it into a clock without losing the ability to use it as a scope.

You probably already know that it’s possible to display your own graphics on an oscilloscope. In fact, you can buy a board from Sparkfun which will turn the scope into an analog clock, and that’s exactly what [Bob] did. But he was met with two problems, the X-axis was flipped and he didn’t have an easy way to power the board.

He struggled with the voltage supply, frying his first attempt at boosting the internal 6.3V supply to use with a linear 5V regulator. His second attempt worked though, soldering a 12V regulator to the transformer. He was then on to the X-axis correction, using a rail-to-rail op-amp to invert the signal. The project finishes by adding toggle controls and buttons on the back of the case to switch between scope and clock modes, and to set the time.

[Jack]’s Solar-powered Clock

December 19, 2011 by 14 Comments

Hack A Day’s own [Jack Buffington] finally finished the solar clock he built for the buildlounge.com laser cutter giveaway.

[Jack] has been putting up the build log on his blog, and now the project is finally complete. The clock operates entirely on solar power. Instead of fancy-smanchy electronics, this clock puts a new spin on the very old school sundial. A box outside [Jack]’s house captures sunlight and focuses it onto an array of optical fibers. These fibers transmit the sunlight though the wall and to the face of the clock. Only a portion of the fibers are lit at any one time, and these correspond to the time of day. With a lot of confusing fiber routing, the clock can indicate the time of day by lighting up the clock face.

We covered the nascent beginnings of this project when it was still a glimmer in [Jack]’s eye, and we’ve got to hand it to him. This is a really creative project, and the addition of the ‘daylight savings time lever’ is the icing on the cake. Check out the video after the break for a great explanation of how the clock actually works, and be sure to check out the project on BuildLounge.

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A Clock Made Out Of Some Very Weird Tubes

December 12, 2011 by 20 Comments

If you’re like [Richard], you’ve got a few really rare components lying around. Maybe it’s a very weird micro or a really tiny CRT, but eventually you’ve got to build something with these parts. When [Richard] decided to put some ITS1A neon display tubes to use, he fell back to the old standby – a really awesome clock.

Unlike the lowly Nixie tube, the ITS1A tube is weird. It’s a neon seven-segment display that can be controlled directly from the pins of a microcontroller. It does this with the help of seven tiny thyratrons in each segment. Even though this tube has neon, the display isn’t the familiar neon orange-red. The tube emits a lovely green with the help of a phosphor coating.

With a single digit already incorporated into [Richard]’s clock, he needed four indicators for the hours and minutes. After a failed experiment with a crazy 4-color, 16-pixel Melz ITM2-M display, he moved on to a simpler MTX90 thyratron indicator.

Using the same control scheme as his earlier numitron clock, Richard had a PCB made and wired everything up. The seven-segment tube indicates the value, and the indicator tubes indicates the position of the digit in the XX:XX standard. A very cool  build with parts you don’t see coming around often.