A Record Lathe For Analog Audio Perfection

October 14, 2025 by Jenny List 11 Comments

It’s no secret that here at Hackaday we’ve at times been tempted to poke fun at the world of audiophiles, a place where engineering sometimes takes second place to outright silliness. But when a high quality audio project comes along that brings some serious engineering to the table we’re all there for it, so when we saw [Slyka] had published the files for their open source record lathe, we knew it had to be time to bring it to you.

Truth be told we’ve been following this project for quite a while as they present tantalizing glimpses of it on social media, so while as they observe, documentation is hard, it should still be enough for anyone willing to try cutting their own recordings to get started. There’s the lathe itself, the controller, the software, and a tool for mapping EQ curves. It cuts in polycarbonate, though sadly there doesn’t seem to be a sound sample online for us to judge.

If you’re hungry for more this certainly isn’t the first record lathe we’ve brought you, and meanwhile we’ve gone a little deeper into the mystique surrounding vinyl.

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2025 Component Abuse Challenge: Making A TTL Demultiplexer Sweat

October 14, 2025 by Jenny List 6 Comments

When we think of a motor controller it’s usual to imagine power electronics, and a consequent dent in the wallet when it’s time to order the parts. But that doesn’t always have to be the case, as it turns out that there are many ways to control a motor. [Bram] did it with a surprising part, a 74ACT139 dual 4-line demultiplexer.

A motor controller is little more than a set of switches between the supply rails and the motor terminals, and thus how it performs depends on a few factors such as how fast it can be switched, how much current it can pass, and how susceptible it is to any back EMF or other electrical junk produced by the motor.

In this particular application the motor was a tiny component in a BEAM robot, so the unexpected TTL motor controller could handle it. The original hack was done a few decades ago and it appears to have become a popular hack in the BEAM community.

This project is part of the Hackaday Component Abuse Challenge, in which competitors take humble parts and push them into applications they were never intended for. You still have time to submit your own work, so give it a go!

The Singing Dentures Of Manchester And Other Places

October 12, 2025 by Jenny List 39 Comments

Any radio amateur will tell you about the spectre of TVI, of their transmissions being inadvertently demodulated by the smallest of non-linearity in the neighbouring antenna systems, and spewing forth from the speakers of all and sundry. It’s very much a thing that the most unlikely of circuits can function as radio receivers, but… teeth? [Ringway Manchester] investigates tales of musical dental work.

Going through a series of news reports over the decades, including one of Lucille Ball uncovering a hidden Japanese spy transmitter, it’s something all experts who have looked at the issue have concluded there is little evidence for. It was also investigated by Mythbusters. But it’s an alluring tale, so is it entirely fabricated? What we can say is that teeth are sensitive to sound, not in themselves, but because the jaw provides a good path bringing vibrations to the region of the ear. And it’s certainly possible that the active chemical environment surrounding a metal filling in a patient’s mouth could give rise to electrical non-linearities. But could a human body in an ordinary RF environment act as a good enough antenna to provide enough energy for something to happen? We have our doubts.

It’s a perennial story (even in fiction), though, and we’re guessing that proof will come over the coming decades. If the tales of dental music and DJs continue after AM (or Long Wave in Europe) transmissions have been turned off, then it’s likely they’re more in the mind than in the mouth. If not, then we might have missed a radio phenomenon. The video is below the break.

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Save Your USB-C Plugs From Oblivion

October 11, 2025 by Jenny List 58 Comments

USB-C as the “One Cable To Rule Them All” has certainly been a success. While USB-A is still around for now, most of us have breathed a hefty sigh of relief with the passing of micro-USB and the several display and power standards it replaces. It’s not without its minor issues though. One of them is that it’s as susceptible as any other cable to a bit of strain. For that, we think [NordcaForm]’s 3D-printed USB-C cable strain relief is definitely a cut above the rest.

Waxing lyrical about a simple 3D printed model might seem overkill for Hackaday, and it’s true, it’s not something we do often, but as Hackaday writers travel around with plenty of USB-C connected peripherals, we like the design of this one. It’s flexible enough to be useful without resorting to exotic filaments, and since it’s available in a few different forms with curved or straight edges, we think it can find a place in many a cable setup. Certainly more of an everyday carry than a previously featured 3D print. If you want to learn more about USB C, we have a whole series of posts for you to binge read.

A Casio Toy Synth Is Ready To ROCK!

October 11, 2025 by Jenny List 7 Comments

There is likely to be more than one of you who has eyed up a child’s toy synthesizer in a second hand store, and considered making something more impressive with it. In many cases these instruments are underwhelming, having a very small subset of functions based into their black-epoxy-blob microcontrollers.

[Make Something] found a Casio toy synth that has a few more functions than the average model, and with the addition of some extra effects electronics and a beautifully made case, turned it into an altogether more interesting instrument.

Most of the video has an element of workshop porn about it, as he makes a very nice Moog-style console case for it, a task made easier by an impressive array of CNC tools. The electronics are slightly more interesting, being a selection of cheap guitar pedals gutted and combined with a cheap tube preamp board. The result is a machine capable of some far more interesting sounds

We think many Hackaday readers would be able to repeat these functions from scratch without the pedals, and while the case is a thing of beauty it’s likely a decent job could be done with a little less finesse on more commonplace tools. Perhaps it’s worth giving those toy synths a second look, because they really can be had for pennies if you look hard enough. Perhaps it’s an easier option than a previous toy musical upgrade.

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The Electret Preamp You Might Need

October 11, 2025 by Jenny List 16 Comments

Electret capsules can be found in some of the highest quality microphones for studio use, as well as in some of the very cheapest microphone capsules on the market. More care and attention has gone into the high-end capsule and its associated circuitry than the cheap one, but is it still possible to get good quality from something costing under a dollar? [Mubarak Basha] thinks so, and has designed a preamp circuit to get the best from a cheap electret capsule.

These capsules may be cheap, but with the addition of a low voltage supply, a resistor, and a capacitor, their internal FET delivers a decent enough input to many a project. To improve on that will need a bit of effort, and in this the preamp delivers by taking care to match impedance, impose a carefully chosen frequency response, and just the right gain to derive a line level output from the electret’s level. It’s hardly a complex circuit, but that’s not always necessary.

As always in these situations, without appropriate test equipment it’s difficult to gauge quality. We’d say this though, if you make one of these and it falls short, you won’t have spent much. Meanwhile if you’re curious about electrets, here’s our guide.

A Function Generator From The Past

October 10, 2025 by Jenny List 12 Comments

It’s always a pleasure to find a hardware hacker who you haven’t seen before, and page back through their work. [Bettina Neumryr]’s niche comes in building projects from old electronics magazines, and her latest, a function generator from the British Everyday Electronics magazine in April 1983, is a typical build.

The project uses the XR2206 function generator chip, a favourite of the time. It contains a current controlled oscillator and waveform shaper, and can easily produce square, triangle, and sine waves. It was always a puzzle back in the day why this chip existed as surely the global market for function generators can’t have been that large, however a little bit of background reading for this write-up reveals that its intended application was for producing frequency-shift-keyed sinusoidal tones.

The two PCBs on the bench, with a multimeter — Yellow-stained boards for the win!

The EE project pairs the XR2206 with an op-amp current generator to control the frequency, and another op-amp as an amplifier and signal conditioner. The power supply is typical of the time too, a mains transformer, rectifier, and linear regulators. There are a pair of very period PCBs supplied as print-outs in the magazine for home etching. This she duly does, though with toner transfer which would have been unheard of in 1983. After a few issues with faulty pots and a miswired switch, she has a working function generator which she puts in a very period project box.

It’s interesting to look at this and muse on what’s changed in electronic construction at our level in the last four decades. The PCB is single sided and has that characteristic yellow of ferric chloride etching, it takes up several times the space achievable with the same parts on the professionally-made dual-sided board designed using a modern PCB CAD package we’d use today. A modern take on the same project would probably use a microcontroller and a DAC, and a small switch-mode supply for less money than that transformer would provide the power. But we like the 1983 approach, and we commend [Bettina] for taking it on. The full video is below the break.

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