An Etch-A-Sketch to Fetch the Time

For someone who has never used stepper motors, real-time clocks, or built anything from scratch, [Dodgey99] has done a great job of bending them to his will while building his Etch-A-Sketch clock.

He used two 5V stepper motors with ULN2003 drivers. These motors are mounted on the back and rotate the knobs via pulleys. They are kind of slow; it takes about 2 1/2 minutes to draw the time, but the point of the hack is to watch the Etch-A-Sketch. [Dodgey99] is working to replace these steppers with Nema 17 motors which are much faster. [Dodgey99] used an EasyDriver for Arduino to drive them. He’s got an Arduino chip kit in this clock to save on the BOM, but you could use a regular Arduino. He left out the 5V regulator because the EasyDriver has one.

[Dodgey99] has published three sketches for the clock: one to set up the RTC so that the correct time is displayed once the Etch-A-Sketch is finished, some code to test the hardware and sample the look of the digits, and the main code to replace the test code.

The icing on this timekeeping cake is the acrylic base and mounting he’s fashioned. During his mounting trials, he learned a valuable lesson about drilling holes into an Etch-A-Sketch. You can’t shake an Etch-A-Sketch programmatically, so he rotates it with a Nema 17. Check it out after the jump.

If you’re paying attention, you’ll realize we just saw the exact opposite of this project a few hours ago: a CNC tool (laser cutter) controlled by turning Etch-A-Sketch knobs.

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Build Your Own Radio Clock Transmitter


Deep in the Colorado foothills, there are two radio transmitters that control the time on millions of clocks all across North America. It’s WWVB, the NIST time signal radio station that sends the time from several atomic clocks over the airwaves to radio controlled clocks across the continent. You might think replicating a 70 kW, multi-million dollar radio transmitter to set your own clock might be out of reach, but with a single ATtiny45, just about everything is possible.

Even though WWVB has enough power to set clocks in LA, New York, and the far reaches of Canada, even a pitifully underpowered transmitter – such as a microcontroller with a long wire attached to a pin PWMing at 60kHz – will be more than enough to overpower the official signal and set a custom time on a WWVB-controlled clock. This signal must be modulated, of course, and the most common radio controlled clocks use an extremely simple amplitude modulation that can be easily replicated by changing the duty cycle of the carrier. After that, it’s a simple matter of encoding the time signal.

The end result of this build is an extremely small one-chip device that can change the time of any remote-controlled clock. We can guess this would be useful if your radio controlled clock isn’t receiving a signal for some reason, but the fact that April 1st is just a few days away gives us a much, much better idea.

A Clock That Plots Time


[Johannes] just sent us a tip about his small plotter that plots out the current time.

[Johannes] small clock plotter uses a dry wipe pen to write out the time on a small piece of dry erase board. The design is Made of three small 9g servos, with one to lift the pen off the writing surface and the other two to control a pair of connected jointed arms for the x and y-axis.

The little robot painstakingly wipes away the previous time before scrawling the current time in its place (with minute accuracy).

[Johannes] had hackability in mind when creating this project, making sure to keep to standard parts and making the code and design files available. The hardware for the build can be laser cut or 3D printed. The Arduino sketch can be found on GitHub and the design files can be found on Thingiverse. There are more detailed build instructions on Nuremberg’s FabLab page (translated).  [Read more...]

A Reel To Reel Clock

And this is how the clock will tell time!

Word clocks – time pieces that spell out the current time with words – are awesome. They’re usually entirely electronic, illuminating LEDs to display the time. Not this one. It’s a mechanical masterpiece that shows the current time in words using motors and 35mm film leader.

The mechanics of this clock are fairly simple: text is transferred onto 35mm film leaders with water slide decals, which are then rolled onto film reels. These film reels are mounted on stepper motors attached to a frame with Meccano. There are four film strips, making this a surprisingly similar a word clock but using motors instead of LEDs.

Because this clock was originally built in 2008, the electronics are a bit… strange through the lens of a post-Arduino skill set. [David] is using a homebrew BASIC Stamp with eight Step Genie ICs and MOSFETs for each motor. Calibration of the clock is handled by an IR detector and a mark on each piece of film leader.

It’s an impressive example of mashing up spare and surplus parts to make something cool, but unfortunately we can’t find a video of this clock in action. If you manage to find one, put a link in the comments and we’ll add it below.

Single Digit Numitron Clock


The above may look like a Nixie tube, but it’s a Numitron: the Nixie’s lower-voltage friend, and part of [pinomelean's] single-digit Numitron clock. If you’re unfamiliar with Numitrons, we suggest you take a look at our post from a few years ago, which includes a helpful tutorial to catch you up to speed.

[pinomelean] built this little device to capture a steampunk-ish look on the cheap for a clock small enough to fit on a wrist. The build uses a PIC16F84A uC and a 4MHz crystal on a custom PCB. A small button on the side lets the wearer set the time. Similar to the Vibrating Timepiece from last month, the Numitron clock isn’t perfect, though it is more accurate: gaining only one minute every 3 days.

Check out the video after the break to see it being set and keeping track of the time. It may take a moment to understand how to read the clock, though. Each of the four LEDs indicates where the number in the Numitron tube belongs. The LEDs light in sequence from left to right, displaying the clock one digit at a time.

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504 Segment Clock


Trying to reinvent the clock has been done over and over again, but it’s always fun to see how over-engineered and complex these designs can get. [Bertho’s] last working clock in his house was the built-in clock on the VCR, so he decided it was finally time to build his own 504 Segment clock.

Yep, that’s right, 504 Segments! This clock uses 72 7-Segment displays to tell time. The video after the break shows the clock in action, but time is read by looking at each ring of displays: outer=seconds, middle=minutes, and inner=hour. [Bertho] could’ve just stopped there, but he decided to load the display up with sensors, so hand-waiving can change modes, and brightness can be regulated based on ambient light conditions. And since he has individual control over each segment, he has implemented some pretty cool mind-melting animations. Oh, and did we mention that the display synchronizes with an NTP server?

The display is divided into 4 quadrants, each containing 18 7-Segment displays. The control architecture is interesting because each quadrant is controlled by its own PIC microcontroller, which handles the continuous multiplexing and modulation of the 18 7-Segment displays.  A main control board contains another (more powerful) PIC to update the 4 quadrants via a serial bus. This board also handles the Ethernet connection, sensor interface, and local RTC(real time clock). This isn’t the first time we’ve seen [Bertho’s] amazing work, so make sure you check out his useless machine and executive decision maker.

[Read more...]

A Vibrating Timepiece


It may not look like much, but the above pictured device is [qquuiinn's] handy little watch that indicates time through pulsed vibrations. Perhaps we should refrain from labeling it as a “watch,” however, considering it’s [qquuiinn's] intention to remove the need to actually look at the thing. Vibrations occur in grandfather clock format, with one long vibration for each hour, accompanied by one, two, or three short pulses for the quarter-hour increments.

The design is straightforward, using an ATTiny85 for the brains along with a few analog components. The vibration motor sticks to the protoboard with some glue, joining the microcontroller, a coin cell battery, and a pushbutton on a small protoboard. The button allows for manual time requests; one press responds with the current time (approximated, probably) in vibrations. The build is a work in progress, and [qquuiinn] acknowledges the lack of an RTC (real-time clock) causes some drift in the timepiece’s accuracy. We suspect, however, that you’d address that problem—twice daily—when you replace the battery: it only lasts ten hours.