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 28 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 15 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.

Listening To Ethernet Via Eurorack

July 26, 2025 by Lewin Day 9 Comments

Ethernet is how we often network computers together, particularly when they’re too important to leave on a fussy WiFi connection. Have you ever thought about listening to Ethernet signals, though? Well, you totally could, with the NSA selector from [wenzellabs].

The NSA selector is a Eurorack module, designed for use as part of a larger modular synthesizer. There are lots of fun jokes and references on the PCB, but the front panel really shows you what this module is all about. It’s got a pair of RJ45 jacks, ready to receive your Ethernet cables through which data is flowing. They’re paired with a single audio output jack. “Any bit on the network will be sent to the audio output,” [wenzellabs] explains.

The device operates in a relatively simple fashion. Network traffic from one jack is forwarded to the other, unmodified. However, it’s also spat out to a simple digital-to-analog converter and turned into audio. This thing doesn’t play digital audio formats or anything like that—it just turns raw Ethernet signalling into audible noise.

Raw signal noises might not sound very appealing, but let’s be real here. If you liked nice sounds, you wouldn’t be into Eurorack. Skip to 25:46 in the video below if you just want to hear the final product.

Continue reading “Listening To Ethernet Via Eurorack” →

A Modern Version Of Famous, Classic Speaker

July 25, 2025 by Bryan Cockfield 12 Comments

Modern musicians may take for granted that a wide array of musical instruments can either be easily connected to a computer or modeled entirely in one, allowing for all kinds of nuanced ways of creating unique sounds and vivid pieces of music without much hardware expense. Not so in the 1930s. Musicians of the time often had to go to great lengths to generate new types of sounds, and one of the most famous of these was the Leslie speaker, known for its unique tremolo and vibrato. Original Leslies could cost thousands now, though, so [Levi Graves] built a modern recreation.

The Leslie speaker itself got its characteristic sound by using two speakers. The top treble speaker was connected to a pair of horns (only one of which produced sound, the other was used for a counterweight) on a rotating platform. The second speaker in the bottom part of the cabinet faced a rotating drum. Both the horns and drum were rotated at a speed chosen by the musician and leading to its unique sound. [Levi] is actually using an original Leslie drum for his recreation but the sound is coming out of a 100-watt “mystery” speaker, with everything packaged neatly into a speaker enclosure. He’s using a single-speed Leslie motor but with a custom-built foot switch can employ more fine-tuned control over the speed that the drum rotates.

Even though modern technology allows us to recreate sounds like this, often the physical manipulation of soundwaves like this created a unique feeling of sound that can’t be replicated in any other way. That’s part of what’s driven the popularity of these speakers throughout the decades, as well as the Hammond organs they’re often paired with. The tone generators on these organs themselves are yet another example of physical hardware providing a unique, classic sound not easily replicated.

Continue reading “A Modern Version Of Famous, Classic Speaker” →

Building A Color Teaching Toy For Tots

July 25, 2025 by Lewin Day No comments

Last year, [Deep Tronix] wished to teach colors to his nephew. Thus, he built a toy to help educate a child about colors by pairing them with sounds, and Color Player was born.

The build is based around the TCS34725, an off-the-shelf color sensor. It’s paired with an ESP32, which senses colors and then plays sounds in turn. [Deep Tronix] made this part harder by insisting on creating their own WAV playback system, using the microcontroller, an SD card, and its on-board digital-to-analog hardware.

The toy operates in three primary modes. Color-to-tone, color-to-sound, color-to-voice. Basically, a color is scanned, and then the Color Player creates a tone, plays back a pre-recorded audio sample, or spells out the name of the color that was just scanned.

[Deep Tronix] also included jolly mode, which just color cycles a few RGB LEDs. However, there’s a game inside jolly mode as well, created for an older nephew to play with. Enter the right button combination, and you unlock it. Then, the device suggests a color and you have to run around, find it, and scan it to score.

We love a good color game; somehow this build seems even more compelling than Milton Bradley’s classic Simon toy.

Continue reading “Building A Color Teaching Toy For Tots” →

Zine Printing Tips From A Solopreneur

July 25, 2025 by Donald Papp 28 Comments

Zines (self-produced, small-circulation publications) are extremely DIY, and therefore punk- and hacker-adjacent by nature. While they can be made with nothing more than a home printer or photocopier, some might benefit from professional production while losing none of their core appeal. However, the professional print world has a few gotchas, and in true hacker spirit [Mabel Wynne] shares things she learned the hard way when printing her solo art zine.

As with assembling hardware kits, assembling a zine can take up a lot of physical table space.

[Mabel] says the most useful detail to nail down before even speaking to printers is the zine’s binding, because binding type can impact layout and design of an entire document. Her advice? Nail it down early, whether it’s a simple saddlestitch (staples through a v-shaped fold of sheets), spiral binding (which allows a document to lay flat), or something else.

Aside from paper and print method (which may be more or less important depending on the zine’s content) the other thing that’s important to consider is the finishing. Finishing consists of things like cutting, folding, and binding of the raw printed sheets. A printer will help arrange these, but it’s possible to do some or even all of these steps for oneself, which is not only more hands-on but reduces costs.

Do test runs, and prototype the end result in order to force unknown problems to the surface before they become design issues. Really, the fundamentals have a lot in common with designing and building kits or hardware. Check out [Mabel]’s article for the full details; she even talks a little about managing money and getting a zine onto shelves.

Zine making is the DIYer’s way to give ideas physical form and put them into peoples’ hands more or less directly, and there’s something wonderfully and inherently subversive about that concept. 2600 has its roots in print, but oddball disk magazines prove one doesn’t need paper to make a zine.