Author: Jenny List

3069 Articles

Designing A Tone Control Properly

April 8, 2025 by 8 Comments

Many years ago, audio equipment came with a tone control, a simple RC filter that would cut or boost the bass to taste. As time passed, this was split into two controls for bass and treble, and then finally into three for bass, mid, and treble. When audiophile fashion shifted towards graphic equalisers, these tone controls were rebranded as “3-band graphic equalisers”, a misleading term if ever we heard one. [Gabriel Dantas] designed one of these circuits, and unlike the simple passive networks found on cheap music centres of old, he’s doing a proper job with active filters.

The write-up is worth a read even if you are not in the market for a fancy tone control, for the basic primer it gives on designing an audio filter. The design contains, as you might expect, a low-pass, a bandpass, and a high-pass filter. These are built around TL072 FET-input op-amps, and an LM386 output stage is added to drive headphones.

The final project is built on a home-made PCB, complete with mains power supply. Audiophiles might demand more exotic parts, but we’re guessing that even with these proletarian components it will still sound pretty good. Probably better than the headphone amplifier featured in a recent project from a Hackaday writer, at least. There’s a build video, below the break.

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The 1980s Computer, French Style

April 7, 2025 by 10 Comments

Should you travel around Europe, you may notice that things in France are ever so slightly different. Not necessarily better or worse, simply that the French prefer to plough their own furrow rather than importing cultural tends from their neighbors.

In the 1980s this was evident in their home computers, because as well as a Minitel terminal in your house, you could have an all-French machine plugged into your TV. [Retro Krazy] has just such a machine — it’s a Matra Hachette Alice 32, and its red plastic case hides hardware any of us would have been proud to own back in the day.

At first sight it appears superficially similar to a Sinclair Spectrum, with its BASIC keywords next to the keys. But under that slightly calculator style AZERTY keyboard is an entirely different architecture, a Motorola 6803. The first Alice computer was a clone of a Radio Shack model, and while this one has no compatibility with its predecessor it retains some silicon choices. On the back are a series of DIN sockets, one for a SCART adapter, and more for serial connectivity and a cassette deck. The overall impression is of a well-engineered machine, even if that red color is a little garish.

The Alice hasn’t appeared here on its own before, but we have taken a look at French retrocomputers here in the past.

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A Tiny Tape Synth

April 7, 2025 by 11 Comments

Afficionados of vintage electric organs will know about the Melotron, an instrument from the 1960s that had pre-recorded sounds on a bank of tape loops. A real Melotron in working order will set you back a bit, but it’s possible to play with the idea using much more attainable hardware. [Decurus] has made a simple tape based synth using a cassette deck.

It uses a loop of cassette tape, and varies the pitch by changing the speed of the cassette motor. There’s an RP2040 and a motor controller, which can take a MIDI signal and use it to drive the motor. We’re sorry to see that there’s no recording of the result, but it’s described as a drone.

Part of this project is a 3D printed tape loop holder to fit a cassette mechanism. We won’t go as far as to call it a cassette in itself, instead it’s a sort of tape loop frame. We can see that it might be an interesting component for other tape loop experimenters, now that cassettes themselves are no longer ubiquitous. This certainly isn’t the first tape pitch synth we’ve seen.

Which Browser Should I Use In 2025?

April 7, 2025 by 60 Comments

Over the history of the Web, we have seen several major shifts in browsing software. If you’re old enough to have used NCSA Mosaic or any of the other early browsers, you probably welcomed the arrival of Netscape Navigator, and rued its decline in the face of Internet Explorer. As Mozilla and then Firefox rose from Netscape’s corpse the domination by Microsoft seemed inevitable, but then along came Safari and then Chrome. For a glorious while there was genuine competition between browser heavyweights, but over the last decade we’ve arrived at a point where Chrome and its associated Google domination is the only game in town. Other players are small, and the people behind Firefox seem hell-bent on fleeing to the Dark Side, so where should we turn? Is there a privacy-centric open source browser that follows web standards and doesn’t come with any unfortunate baggage in the room? It’s time to find out. Continue reading “Which Browser Should I Use In 2025?” →

A Tale Of Nuclear Shenanigans From Down Under

April 6, 2025 by 45 Comments

It’s likely that among the readers of this article there will be many who collect something. Whether it’s rare early LEDs or first-year-of-manufacture microprocessors, you’ll scour the internet to find them, and eagerly await mystery packages from the other side of the world.

There’s a tale emerging from Australia featuring just such a collector, whose collection now has him facing a jail sentence for importing plutonium. The story however is not so clear-cut, featuring a media frenzy and over-reaction from the authorities worthy of Gatwick Airport. [Explosions&Fire] has a rather long video unpacking the events, which we’ve placed below the break.

Emmanuel Lidden is an element collector, someone who tries to assemble an entire Periodic Table in their collection. He ordered a range of elements from an American element collectors’ supply website, including samples of plutonium and thorium. He seems to have been unaware he was committing any crime, with the microscopic samples available from legitimate websites with no warnings attached. The case becomes murkier as the Australian authorities flagged the thorium sample and instructed the courier not to deliver it, which they did anyway. Then a raid of the type you’d expect for the terrorists who stole the plutonium in Back To The Future was launched, along with that Gatwick-esque media frenzy.

We’re inclined to agree that the penalty likely to be meted out to him for buying a sliver of a Soviet smoke detector embedded in a Lucite cube seems overly steep, but at the same time his obvious naivety over dealing in radioactive materials marks him as perhaps more than a little foolhardy. It’s something over which to ponder though, have we managed to amass anything illegal disguised as outdated devices? Have you? Perhaps it’s something to discuss in the comments.

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An Amstrad PCW Receives A Bit Of Love

April 6, 2025 by 5 Comments

If Clive Sinclair’s genius in consumer electronics was in using ingenious hacks to make cheaper parts do greater things, then his Amstrad competitor Alan Sugar’s was in selling decade-old technology to consumers as new and exciting. His PCW series of computers are a great example, 1970s CP/M machines smartly marketed for late 1980s home offices. They were a popular choice at the time, and [Retro Recipes] has one. In  a video filmed in period standard definition he’s taking us through a repair to its Gotek drive, and then a RAM upgrade.

The repair and upgrade are fairly straightforward, the former being a failed OLED screen on the drive and the latter being the installation of a bank of DIP memory chips. The interest lies in how they cost-minimised a CP/M machine as a consumer product. The board relies heavily on custom chips as you might expect, and there’s a brief glimpse of one of those unusual 3″ floppy drives. The power supply is part of the monitor board as was often the case with Amstrad machines, and the whole thing is about as simple as it can be. The full video can be found below the break.

We’re guessing that particularly in the UK there will be plenty of PCWs still languishing in dusty attics, but surprisingly given their popularity at the time we see less of them that might be expected. There has been a significantly upgraded model on these pages though.

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A Low F Number Lens, From Scratch

April 6, 2025 by 54 Comments

The F-number of a photographic lens is a measure of its light-gathering ability, and is expressed as its aperture diameter divided by its focal length. Lenses with low F-numbers are prized by photographers for their properties, but are usually expensive because making a good one can be something of a challenge. Nevertheless [Rulof] is giving it a go, making an 80mm F0.5 lens with a Sony E-mount. The video below the break has all the details, and also serves as a fascinating primer on lens design if you are interested.

Rather than taking individual lenses, he’s starting with the second-hand lens from an old projector. It’s got the required huge aperture, but it’s by no means a photographic lens. An interesting component is his choice of diaphragm for the variable aperture, it’s a drafting aid for drawing circles which closely resembles a photographic part. This is coupled with the triplet from an old SLR lens in a 3D-printed enclosure, and the result is a lens that works even if it may not be the best. We know from experiences playing with lens systems that adjusting the various components of a compound lens like this one can be very difficult; we can see it has the much sought-after bokeh or blurred background, but it lacks sharpness.

Perhaps because a camera is an expensive purchase, we don’t see as much of this kind of hacking as we’d like. That’s not to say that lenses don’t sometimes make their way here.

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