Author: Jenny List

3386 Articles

Hackaday Podcast Episode 341: Qualcomm Owns Arduino, Steppers Still Dominate 3D Printing, And Google Controls Your Apps

October 10, 2025 by 2 Comments

The nights are drawing in for Europeans, and Elliot Williams is joined this week by Jenny List for an evening podcast looking at the past week in all things Hackaday. After reminding listeners of the upcoming Hackaday Supercon and Jawncon events, we take a moment to mark the sad passing of the prolific YouTuber, Robert Murray-Smith.

Before diving into the real hacks, there are a couple of more general news stories with an effect on our community. First, the takeover of Arduino by Qualcomm, and what its effect is likely to be. We try to speculate as to where the Arduino platform might go from here, and even whether it remains the player it once was, in 2025. Then there’s the decision by Google to restrict Android sideloading to only approved-developer APKs unless over ADB. It’s an assault on a user’s rights over their own hardware, as well as something of a blow to the open-source Android ecosystem. What will be our community’s response?

On more familiar territory we have custom LCDs, algorithmic art, and a discussion of non-stepper motors in 3D printing. Even the MakerBot Cupcake makes an appearance. Then there’s a tiny RV, new creative use of an ESP32 peripheral, and the DVD logo screensaver, in hardware. We end the show with a look at why logic circuits use the voltages they do. It’s a smorgasbord of hacks for your listening enjoyment.

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Inside A Germanium Transistor

October 10, 2025 by 9 Comments

The first transistors were point contact devices, not far from the cats-whiskers of early radio receivers. They were fragile and expensive, and their performance was not very high. The transistor which brought the devices to a mass audience through the 1950s and 1960s was the one which followed, the alloy diffusion type. [Play With Junk] has a failed OC71 PNP alloy diffusion transistor, first introduced in 1957, and has cracked it open for a closer look.

Inside the glass tube is a small wafer of germanium crystal, surrounded by silicone grease. It forms the N-type base of the device, with the collector and emitter being small indium beads fused into the germanium. The junctions were formed by the resulting region of germanium/indium alloy. The outside of the tube is pained black because the device is light-sensitive, indeed a version of this transistor without the paint was sold as the OCP71 phototransistor.

These devices were leaky and noisy, with a low maximum frequency and low gain. But they were reliable and eventually affordable, so some of us even cut our electronic teeth on them.

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Google Japan Turn Out Another Keyboard, And It’s A Dial

October 9, 2025 by 19 Comments

There’s a joke that does the rounds, about a teenager being given a dial phone and being unable to make head nor tail of it.  Whether or not it’s true, we’re guessing that the same teen might be just a stumped by this year’s keyboard oddity from Google Japan. It replaces keys with a series of dials that work in the same way as the telephone dial of old. Could you dial your way through typing?

All the files to make the board, as well as a build guide, are in the GitHub repository linked above, but they’ve also released a promotional video that we’ve put below the break. The dials use 3D printed parts, and a rotary encoder to detect the key in question. We remember from back in the day how there were speed dialing techniques with dial phones, something we’ve probably by now lost the muscle memory for.

We like this board for its quirkiness, and while it might become a little tedious to type a Hackaday piece on it, there might be some entertainment for old-timers in watching the youngsters figuring it out. If you’re hungry for more, we’ve covered them before.

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A Minicomputer Tape Drive Receives Some Love

October 8, 2025 by 6 Comments

Taking on a refrigerator-sized minicomputer  is not for the faint-hearted, but [Usagi Electric] has done it with a DEC PDP-11/44. He’s not doing it in half measures either, for his machine is tricked out with an impressive array of upgrades. Among them however is no storage, and with two co-processors there’s a meager 3U of rack space left. The plan is to fit a period 8″ hard drive in the space alongside a TU50 tape dive, and it’s this final component that’s the subject of his latest video.

DEC never did anything by halves, and a DECTape II cartridge is more than a simple container for tape reels. Instead it has a capstan of its own that engages with one in the drive, and an internal drive belt that moves the reels. All the rubber parts in both tapes and drive are thoroughly perished, and it’s impressive that he manages to find inexpensive modern polymer alternatives. The original drive is probably intended for a VAX system, thus it has the interesting feature of a second drive mechanism out of sight to hold a tape containing microcode.

Having reconditioned the drive, it goes in behind a custom front panel, and though there’s no useful data to test it with on the tapes he has, it appears all working. You can see it all in the video below the break, and if you’re interested further we’ve covered this machine in the past.

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Can A Coin Cell Make 27 Volts?

October 7, 2025 by 8 Comments

We have all no doubt at some point released the magic smoke from a piece of electronics, it’s part of what we do. But sometimes it’s a piece of electronics we’re not quite ready to let go, and something has to be fixed. [Chris Greening] had a board just like that, a 27 volt generator from an LCD panel, and he crafted a new circuit for it.

The original circuit, which we think he may have drawn incorrectly, uses a small boost converter IC with the expected inductor and diode. His replacement is the tried and tested joule thief, but with a much higher base resistor than its normal application in simply maintaining a battery voltage. It sucks 10 mA from the battery and is regulated with a Zener diode, but there’s still further room for improvement. Adding an extra transistor and using the Zener as a feedback component causes the oscillator to shut off as the voltage increases, something which in this application is fine.

It’s interesting to see a joule thief pushed into a higher voltage application like this, but we sense perhaps it could be made more efficient by seeking out an equivalent to the boost converter chip. Or even a flyback converter.

A Lorenz Teletype Shows Us Its Secrets

October 7, 2025 by 23 Comments

When we use the command line on Linux, we often refer to it as a terminal. It’s a word with a past invoking images of serial terminals, rows of green-screened machines hooked up to a central computer somewhere. Those in turn were electronic versions of mechanical teletypes, and it’s one of these machines we’re bringing you today. [DipDoT] has a Lorenz teletype from the 1950s, and he’s taking us through servicing and cleaning it, eventually showing us its inner workings.

The machine in question had been in storage for many years, but remained in good condition. To be this long out of use though meant it needed a thorough clean, so he sets about oiling the many hundreds of maintenance points listed in a Lorenz manual. It’s a pleasant surprise for us to see keyboard and printer unit come away from the chassis for servicing so easily, and by stepping it through its operation step by step we can see how it works in detail. It even incorporates an identifier key — think of it as a mechanical ROM that stores a sequence of letters — which leads him to believe it may have come from a New York news office. The video is below the break, and makes for an interesting watch.

He’s going to use it with a relay computer, but if you don’t have one of those there are more modern ways to do it.

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Know Audio: Distortion Part Two

October 6, 2025 by 16 Comments

It’s been a while since the last installment in our Know Audio series, in which we investigated distortion as it applies to Hi-Fi audio. Now it’s time to return with part two of our look at distortion, and attempt some real-world distortion measurements on the bench.

Last time, we examined distortion from a theoretical perspective, as the introduction of unwanted harmonics as a result of non-linearities in the signal path. Sometimes that’s a desired result, as with a guitar pedal, but in a Hi-Fi system where the intention is to reproduce as faithfully as possible a piece of music from a recording, the aim is to make any signal path components as linear as possible. When we measure the distortion, usually expressed as THD, for Total Harmonic Distortion, of a piece of equipment we are measuring the ratio of those unwanted harmonics in the output to the frequencies we want,  and the resulting figure is commonly expressed in dB, or as a percentage. Continue reading “Know Audio: Distortion Part Two” →