2025 One-Hertz Challenge: Shadow Clock

July 26, 2025 by Lewin Day No comments

You can buy all kinds of conventional clocks that have hands and numbers for easy reading. Or, like [Fabio Ricci], you could build yourself something a little more esoteric, like this neat shadow clock.

The heart of the build is an ESP8266 microcontroller, which gets the current time via Wi-Fi by querying an NTP time server. It also uses a DS3231 real-time clock module as a backup, keeping accurate time even when a network connection is unavailable.

Time is displayed via a 60-pixel ring of WS2812B addressable LEDs. These 60 LEDs correspond to the usual per-minute graduations that you would find on a regular clock. Current hour is displayed by lighting the corresponding LED red, while minutes are shown in blue and seconds in white. It’s called a “shadow clock” because of its method of activation. IR distance sensors are used to activate the time display when a hand or finger is placed near the clock. As Fabio puts it, “shadow play” will make the clock display the time. Otherwise, it switches to be a simple round device on the wall that displays colorful animations.

It’s a neat build that looks quite unassuming as a decor piece, and yet it also serves as an easy-to-read timepiece. We’ve seen LEDs put to all sorts of good uses in clock builds around these parts. Meanwhile, if you’ve found your own unique way to display the time—either in readable fashion, or totally oblique—don’t hesitate to let us know.

Vintage Plasma Display Shows Current Rad Levels

July 26, 2025 by Tyler August 3 Comments

It’s hard to argue that Soviet-Era nuclear engineering may have some small flaws, what with the heavily-monitored exclusion zone around Chernobyl No.4. Evidently, their industrial designers were more on-the-ball, because [Alex] has crafted the absolute most stylish fallout monitor we’ve ever seen, with ESP32 and a vintage Soviet-designed plasma display to indicate radiation levels in the exclusion zone.

Since the device is not located within the zone, [Alex] is using the ESP32 to access sensor values published via an API at SaveEcoBot. He also includes a Geiger counter module for the background level at the current location. That’s straightforward enough– integrating the modern microcontroller with the vintage plasma display is where the real hacking comes in. Though they might not be as vintage as you think: apparently the Elektronika MS6205 remained in production until 2005, but 2005 is still vintage. [Alex] notes in the instructions on hackaday.io that we’re actually looking for a post-1995 model to follow along.

The Elektronika MS6205 is based on a 100×100 pixel plasma matrix, but it is operated as a text-only display with Latin and Cyrillic characters in ROM. The ROM also includes some extra symbols and Greek letters (the gamma will come in handy for this application) that can be unlocked by cutting a trace on the board and replacing it with a bodge wire. Igniting the display requires 250V, which will require more work for North Americans than it does in Ukraine. Driving the display requires interfacing with the 7-bit data bus and 8-bit address bus, but [Alex] has made the wiring and code available on the project site if you’re interested in these devices. If you want to watch it in action and get more background, check out the video embedded below.

These sorts of monochrome plasma displays have a lot of charm, and are absolutely worth reverse-engineering if you get your hands on different model. If you like the vibe of this display, you might also be interested in Vacuum Fluorescent Displays, which can be easier to find in the West.

Thanks to [Alex] for the tip. Like the tireless IEA workers at Chernobyl, we’re always monitoring the radiation level of our tips line. Continue reading “Vintage Plasma Display Shows Current Rad Levels” →

Engrave A Cylinder Without A Rotary Attachment? No Problem!

July 26, 2025 by Donald Papp No comments

Laser-engraving a cylindrical object usually requires a rotary attachment, which is a motorized holder that rotates a cylindrical object in sync with the engraver. But [Samcraft] shows that engraving all around a mug can be done without a motorized rotary holder.

Separating a design into elements thin enough to engrave individually without losing focus is the key.

The basic idea is to split the design into a number of separate engraving jobs, each containing one element of the overall design, then setting the mug into a 3D printed jig and manually rotating it between jobs. To demonstrate, [Samcraft] selects a series of line-art flowers and plants which are ideal for this approach because there’s no need to minutely register the individual engravings with one another.

What about focus? [Samcraft] found that a design up to 45 mm wide could be engraved onto the curved surface of his mug before focus suffers too much. It’s true that this technique only works with certain types of designs — specifically those with individual elements that can be separated into tall and thin segments — but the results are pretty nice.

Laser engravers are a very serious potential eye hazard, and we are not delighted to see the way the shield around [Samcraft]’s engraver cannot close completely to accommodate the mug while the laser is active. But we’re going to assume [Samcraft] has appropriate precautions and eye protection in place off-camera, because laser radiation and eyeballs absolutely do not belong together, even indirectly.

Continue reading “Engrave A Cylinder Without A Rotary Attachment? No Problem!” →

2025 One-Hertz Challenge: A Clock Sans Silicon

July 26, 2025 by Lewin Day 7 Comments

Just about every electronic device has some silicon semiconductors inside these days—from transistors to diodes to integrated circuits. [Charles] is trying to build a “No-Silicon digital clock” that used none of these parts. It looks like [Charles] is on the way to success, but one might like to point out an amusing technicality. Let’s dive in to the clock!

Instead of silicon semiconductors, [Charles] is attempting to build a digital clock using valves (aka tubes). More specifically, his design relies on seven dekatrons, which are the basic counting elements of the clock. By supplying the right voltages to the various cathodes of the dekatrons, they can be made to step through ten (or sometimes twelve) stable states, used as simple memory elements which can be used as the basis for a timepiece. [Charles] will set up the first dekatron to divide down mains frequency by 5 or 6 to get down to 10 Hz, depending on whether the supply is 50 Hz or 60 Hz. The next dekatron will step down 10 times to 1 Hz, to measure seconds. The next two will divide by ten and six to count minutes, while a further two will divide the same way to create an impulse per hour. A final dekatron will divide by 12 to count the hours in a day.

Naturally, time will be displayed on Nixies. While silicon semiconductors are verboten, [Charles] is also considering the use of some germanium parts to keep the total tube count down when it comes to supporting hardware. Also, [Charles] may wish to avoid silicon, but here’s the thing about tubes. They use glass housings, and glass is made of silicon.

Cheeky technicalities aside, it’s a great project that promises to create a very interesting clock indeed. Progress is already steaming along and we can’t wait to see the finished product. We’ve seen dekatrons put to good use before, too. If you’re cooking up your own practical projects with mid-century hardware, don’t hesitate to let us know!

Signal Injector Might Still Be Handy

July 26, 2025 by Al Williams 1 Comment

Repairing radios was easier when radios were simple. There were typically two strategies. You could use a signal tracer (an amplifier) to listen at the volume control. If you heard something, the problem was after the volume control. If you didn’t, then the problem was something earlier in the signal path. Then you find a point halfway again, and probe again. No signal tracer? You can also inject a signal. If you hear it, the problem is before the volume. If not, it is after. But where do you get the signal to inject? [Learn Electronics Repair] sets out to make a small one in a recent video you can see below.

Both signal tracers and injectors were once ubiquitous pieces of equipment when better options were expensive. However, these days, you can substitute an oscilloscope for a signal tracer and a signal generator for an injector. Still, it is a fun project, and a small dedicated instrument can be handy if you repair a lot of radios.

The origin of this project was from an earlier signal injector design and a bet with a friend about making a small version. They are both working on their designs and want people to submit their own designs for a little ad hoc contest.

We always preferred a signal tracer since it is more passive. Those were typically just audio amplifiers with an optional diode in the input to demodulate RF. A computer amplified speaker and a diode can do the job, as can an LM386. Or, you can build something complex, if you prefer.

Continue reading “Signal Injector Might Still Be Handy” →

Personalization, Industrial Design, And Hacked Devices

July 26, 2025 by Elliot Williams 14 Comments

[Maya Posch] wrote up an insightful, and maybe a bit controversial, piece on the state of consumer goods design: The Death Of Industrial Design And The Era Of Dull Electronics. Her basic thesis is that the “form follows function” aesthetic has gone too far, and all of the functionally equivalent devices in our life now all look exactly the same. Take the cellphone, for example. They are all slabs of screen, with a tiny bezel if any. They are non-objects, meant to disappear, instead of showcases for cool industrial design.

Of course this is an extreme example, and the comments section went wild on this one. Why? Because we all want the things we build to be beautiful and functional, and that has always been in conflict. So even if you agree with [Maya] on the suppression of designed form in consumer goods, you have to admit that it’s not universal. For instance, none of our houses look alike, even though the purpose is exactly the same. (Ironically, architecture is the source of the form follows function fetish.) Cars are somewhere in between, and maybe the cellphone is the other end of the spectrum from architecture. There is plenty of room for form and function in this world.

But consider the smartphone case – the thing you’ve got around your phone right now. In a world where people have the ultimate homogeneous device in their pocket, one for which slimness is a prime selling point, nearly everyone has added a few millimeters of thickness to theirs, aftermarket, in the form of a decorative case. It’s ironically this horrendous sameness of every cell phone that makes us want to ornament them, even if that means sacrificing on the thickness specs.

Is this the same impetus that gave us the cyberdeck movement? The custom mechanical keyboard? All kinds of sweet hacks on consumer goods? The need to make things your own and personal is pretty much universal, and maybe even a better example of what we want out of nice design: a device that speaks to you directly because it represents your work.

Granted, buying a phone case isn’t necessarily creative in the same way as hacking a phone is, but it at least lets you exercise a bit of your own design impulse. And it frees the designers from having to make a super-personal choice like this for you. How about a “nothing” design that affords easy personalized ornamentation? Has the slab smartphone solved the form-versus-function fight after all?

Read QR Codes On The Cheap

July 26, 2025 by Al Williams 8 Comments

Adding a camera to a project used to be a chore, but modern camera modules make it simple. But what if you want to read QR codes? [James Bowman] noticed a $7 module that claims to read QR codes so he decided to try one out.

The module seems well thought out. There’s a camera, of course. A Qwiic connector makes hooking up easy. An LED blinks blue when you have power and green when a QR code shows up.

Reading a QR code was simple in Python using the I2CDriver library. There are two possible problems: first, if the QR code contains a large amount of data, you may exceed the I2C limit of 254 bytes. Second, despite claiming a 110-degree field of view, [James’] testing showed the QR code has to be almost dead center of the camera for the system to work.

What really interested us, though, was the fact that the device is simply a camera with an RP2040 and little else. For $7, we might grab one to use as a platform for other imaging projects. Or maybe we will read some QR codes. We’d better pick up a few. Then again, maybe we can just do it by hand.