Building A 7-Segment Shadow Clock

August 10, 2025 by 6 Comments

There are plenty of conventional timepieces out there in the world; we’ve also featured a great many that are aesthetically beautiful while being unreadably esoteric. This neat “shadow clock” from [Smart Solutions for Home] is not conventional, but it’s still a clock you could use every day.

The display is made of four seven-segment digits, which have a subtle appearance. Each segment uses a solenoid to extend it forward out of the display, or to retract it flush with the faceplate. This creates a numerical display in all one color, with the physical protrusion doing the job of making the numbers visible. This is perhaps where the “shadow clock” name comes from, though you notice the protruding segments moreso than the shadows they cast on the faceplate.

Running the show is an ESP32, paired with H-bridges to drive the solenoids that make up the 7-segment displays. The H-bridges are driven via shift registers to reduce the number of GPIO pins needed. Unlike many other ESP32 clock builds, this one uses a DS3231 real-time clock module to keep accurate time, rather than solely relying on Internet-based NTP time servers. Configuring the clock can be done via a web interface. Design files are available online.

If you think you’ve seen this recently, maybe you’re thinkig of this prototype for a very similar display by [indoorgeek]. And that’s not the only way to make shadow clocks either. After all, the term is not enforced or defined by any global horological organization. Maybe that’s a good thing! Video after the break.

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Cheap Thermal Camera Fits The Bill

August 10, 2025 by 14 Comments

If you want to save a little money on a thermal camera, or if you just enjoy making your own, you should have a look at [Evan Yu’s] GitHub repository, which has a well thought out project built around the MLX90640 and an ESP32. The cost is well under $100. You can watch it do its thing in the video below.

There’s a PCB layout, a 3D-printed case, and — of course — all the firmware files.  The code uses the Arduino IDE and libraries. It leverages off-the-shelf libraries for the display and the image sensor.

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SparcStation 1+ Finally Gets Attention

August 9, 2025 by 12 Comments

We can’t throw stones. [Leaded Solder] picked up a SparcStation 1+ in 2018 and found it only produced illegal instruction errors. We’re sure he’s like us and meant to get back to it, and, instead, it sat on the bench, taking up space. You eventually have to move it, though, so seven years later, it was time for another go at it.

The first pass back in 2018 revealed that the machine had an interesting life. The full-sized hard drive was salvaged from an Apple computer. Removing the drive resolved the illegal instruction error. The drive seemed to work, but there was still nothing that suggested the machine would fully boot up. The next step was to try booting from a floppy, but that didn’t work either. The floppy cable had been surgically altered, again hinting this machine had seen some tough love.

Fast forward to 2025. This time, a Pi Pico-based SCSI emulator would stand in for the aging and suspect hard drive. Unfortunately, as noted, this machine has undergone some extensive and strange surgery. The power cable feeding the emulator had been rewired backwards, exposing the poor Pi Pico to 12 V, with predictable results. Luckily, it didn’t seem to phase the SparcStation.

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A photo of the PDP-1 replica.

Hacking Printed Circuit Board To Create Casing And Instrument Panels

August 9, 2025 by 11 Comments

Over on Hackaday.io our hackers [Angelo] and [Oscarv] are making a replica of the PDP-1. That is interesting in and of itself but the particularly remarkable feature of this project is its novel use of printed circuit boards for casing and instrument panels.

What does that mean in practice? It means creating a KiCad file with a PCB for each side of the case/panel. These pieces can then be ordered from a board house and assembled. In the video below the break you will see an example of putting such a case together. They use sticky tape for scaffolding and then finish things off by soldering the solder joints on each edge together.

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Desk Top Peltier-Powered Cloud Chamber Uses Desktop Parts

August 9, 2025 by 6 Comments

There was a time when making a cloud chamber with dry ice and alcohol was one of those ‘rite of passage’ type science projects every nerdy child did. That time may or may not be passed, but we doubt many children are making cloud chambers quite like [Curious Scientist]’s 20 cm x 20 cm Peltier-powered desktop unit.

The dimensions were dictated by the size of the off-the-shelf display case which serves as the chamber, but conveniently enough also allows emplacement of four TEC2-19006 Peltier cooling modules. These are actually “stacked” modules, containing two thermoelectric elements in series — a good thing, since the heat delta required to make a cloud chamber is too great for a single element. Using a single-piece two stage module simplifies the build considerably compared to stacking elements manually.

To carry away all that heat, [Curious Scientist] first tried heatpipe-based CPU coolers, but moved on to CPU water blocks for a quieter, more efficient solution. Using desktop coolers means almost every part here is off the shelf, and it all combines to work as well as we remember the dry-ice version. Like that childhood experiment, there doesn’t seem to be any provision for recycling the condensed alcohol, so eventually the machine will peter out after enough vapor is condensed.

This style of detector isn’t terribly sensitive and so needs to be “seeded” with spicy rocks to see anything interesting, unless an external electric field is applied to encourage nucleation around weaker ion trails. Right now [Curious Scientist] is doing that by rubbing the glass with microfiber to add some static electricity, but if there’s another version, it will have a more hands-off solution.

We’ve seen Peltier-Powered cloud chambers before (albeit without PC parts), but the “dry ice and alcohol” hack is still a going concern. If even that’s too much effort, you could just go make a cup of tea, and watch very, very carefully.

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2025 One Hertz Challenge: Estimating Pi With An Arduino Nano R4

August 9, 2025 by 10 Comments

Humanity pretty much has Pi figured out at this point. We’ve calculated it many times over and are confident about what it is down to many, many decimal places. However, if you fancy estimating it with some electronic assistance, you might find this project from [Roni Bandini] interesting.

[Roni] programmed an Arduino Nano R4 to estimate Pi using the Monte Carlo method. For this specific case, it involves drawing a circle inscribed inside a square. Points are then randomly scattered inside the square, and checked to see if they lie inside or outside the circle based on their position and distance of the circle’s outline from the center point of the square. By taking the ratio of the points inside the circle to the total number of points, you get an approximation of the ratio of the square and circle’s areas, which is equal to Pi/4. Thus, multiply the ratio by 4, and you’ve got your approximation of Pi.

[Roni] coded a program to run the Monte Carlo simulation on the Arduino Nano R4, taking advantage of the mathematical benefits of its onboard Floating Point Unit. It generates 100 new samples for the Monte Carlo approximation every second, improving the estimation of pi as it goes. It then displays the result on a 7-segment display, and beeps as it goes. [Roni] readily admits the project is a little too close in appearance to a classic Hollywood bomb.

We’ve seen some other neat Pi-calculating projects before, too.

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The Kilopixel Display

August 9, 2025 by 7 Comments

Despite the availability of ready-made displays never being better, there are still some hardy experimenters who take on the challenge of making their own. In [Ben Holmen]’s case the display he built is somewhat unusual and not the most practical, but for us a giant-sized wooden kilopixel display is exactly what the world needs.

It’s a kilopixel display because it has a resolution of 40 by 25 pixels, and it takes the form of a rack of wooden cubes, each of which can be turned by a tool on a gantry to expose either a black or a white side. It’s very slow indeed — he has an over nine hour long video of it in operation — but it is an effective device.

His write-up goes into great detail about the steps taken in its design, starting with spherical pixels rotated by a LEGO wheel and progressing to cubes poked at their corner to rotate. The pusher in this case is a hot glue stick, for the required flexibility. For practicality we’re reminded of this serial oil-and-water display.

The whole thing is online, and if you want you can submit your own images for it to draw. Whether a Wrencher in 25 pixel resolution has enough detail, we’ll leave to you.