Making The Commodore SX-64 Mini

February 19, 2024 by 12 Comments

When you find a portable TV from the 1980s, and it reminds you of the portable Commodore 64, there’s only one thing to be done. [Aaron Newcomb] brings us the story of taking an Emerson PC-6 and mating it to the guts of his THEC64 Mini. It’s a bit of a journey, as the process includes modding the TV to include a composite input and trimming some unused PCB off the TV’s mainboard. Then some USB ports and a three-and-a-half inch floppy drive were shoehorned into the chassis, with the rear battery compartment holding the parts from THEC64 Mini.

The build was not entirely without issue. It turns out the degaussing coil connector can plug perfectly into the service port, and Murphy’s law proved itself true again. But no harm was done, and the error was quickly discovered. All that was left was to button the chassis back up and add some paint and 3d-printed trim details. The build looks great! Come back after the break to watch the video from the [Retro Hack Shack] for yourself.

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Parts We Miss: The Mains Transformer

February 14, 2024 by 57 Comments

About two decades ago there was a quiet revolution in electronics which went unnoticed by many, but which overturned a hundred years of accepted practice. You’d have noticed it if you had a mobile phone, the charger for your Nokia dumbphone around the year 2000 would have been a weighty device, while the one for your feature phone five years later would have been about the same size but relatively light as a feather. The electronics industry abandoned the mains transformer from their wall wart power supplies and other places in favour of the much lighter and efficient switch mode power supply. Small mains transformers which had been ubiquitous in electronics projects for many years, slowly followed suit.

Coils Of Wire, Doing Magic With Electrons

Inside and outside views of Jenny Lists's home made linear power supply from about 1990
This was a state of the art project for a future Hackaday scribe back in 1990.

A transformer works through transferring alternating electrical current into magnetic flux by means of a coil of wire, and then converting the flux back to electric current in a second coil. The flux is channeled through a ferromagnetic transformer core made of iron in the case of a mains transformer, and the ratio of input voltage to output voltage is the same as the turns ratio between the two. They provide a safe isolation between their two sides, and in the case of a mains transformer they often have a voltage regulating function as their core material is selected to saturate should the input voltage become too high. The efficiency of a transformer depends on a range of factors including its core material and the frequency of operation, with transformer size decreasing with frequency as efficiency increases.

When energy efficiency rules were introduced over recent decades they would signal the demise of the mains transformer, as the greater efficiency of a switch-mode supply became the easiest way to achieve the energy savings. In a sense the mains transformer never went away, as it morphed into the small ferrite-cored part running at a higher frequency in the switch-mode circuitry, but it’s fair to say that the iron-cored transformers of old are now a rare sight. Does this matter? It’s time to unpack some of the issues surrounding a small power supply. Continue reading “Parts We Miss: The Mains Transformer” →

Piezo Transducers Could Turn Displays Into Speakers

February 13, 2024 by 28 Comments

Will piezoelectric-based speakers replace traditional speakers over the coming years in space-constrained devices? We have definitely seen the use of piezo transducers in e.g. high-end televisions that use the display’s surface not just for the visual content, but also as a highly dynamic speaker. If you extrapolate this principle to something like smartphones, tablets and laptops the advantages are clear: piezoelectric transducers are smaller, more power efficient and do not need any holes in the enclosure. These and other advantages are what [Vineet Ganju] argues in IEEE Spectrum will push the market to adopt this new technology.

When piezoelectric transducers vibrate the display itself to create sound waves, the sound seems to come directly from the image on the screen, a much more realistic effect. (Credit: James Provost)
Piezoelectric transducers vibrate the display itself to create sound waves. (Credit: James Provost)

[Vineet] is the Vice President and General Manager of the audio business unit of Synaptics — which is one of the companies pushing for these piezoelectric transducers to be used for speaker purposes — so there is definitely some bias involved. Even so, it’s undeniable that the speakers in portable devices as well as the average flat panel TV aren’t exactly amazing, with the limited space meaning that audio quality suffers, with lows being generally absent and the resulting audio sounding ‘tinny’. Generally this is where people get external speakers for their TV, and lug portable speakers along with their laptop and other mobile devices.

For TVs, Sony has pushed for its Acoustic Surface Audio technology that uses two or three piezoelectric transducers on their OLED panels, while Samsung sticks to traditional speakers, but places lots of them around the screen with its Object Tracking Sound technology.

Sony’s technology cannot be used with LCD panels, due to the backlight being in the way, so the interesting question here is whether the piezoelectric speaker revolution proposed by [Vineet] will be limited to devices that use OLED or similar backlight-less displays?

Ethernet For Hackers: The Very Basics

February 12, 2024 by 92 Comments

Ethernet is ubiquitous, fast, and simple. You only need two diffpairs (four wires) to establish a 100Mbit link, the hardware is everywhere, you can do Ethernet over long distances easily, and tons of the microcontrollers and SoCs support it, too. Overall, it’s a technology you will be glad to know about, and there’s hundreds of scenarios where you could use it.

If you need to establish a high-bandwidth connection between two Linux boards in your project, or maybe a Linux board and a powerful MCU, maybe make a network between microcontrollers, Ethernet’s your friend. It also scales wonderfully – there’s so much tech around Ethernet, that finding cables, connectors or ICs tends to be dead easy. Plus, the world of Ethernet is huge beyond belief. Ethernet as most of us know it is actually just the consumer-facing versions of Ethernet, and there’s a quite a few fascinating industrial and automotive Ethernet standards that flip many of our Ethernet assumptions upside down.

Now, you might be missing out on some benefits of Ethernet, or perhaps misunderstanding how Ethernet works at all. What does it mean when a microcontroller datasheet says “has Ethernet interface”? If you see five pins on an SBC and the manufacturer refers to them as “Ethernet”, what do you even do with them? Why does the Raspberry Pi 4 SoC support Ethernet but still requires an extra chip, and what even is GMII? Continue reading “Ethernet For Hackers: The Very Basics” →

Printing A Log

February 11, 2024 by 16 Comments

We’ve used wood filament before, and we hazily remember a Cura plugin that changed temperatures to create wood grain. But unlike [Patrick Gibney], we never thought of printing a faux wood log coaster that looks like it has rings. Check out the video below to see how it works.

The filament is not really wood, of course, but a polymer — usually PLA — mixed with wood particles. Changing the temperature does a nice job of darkening the wood. However, it also changes the properties of the carrier polymer, and that’s not always a good thing.

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Friendly Flexible Circuits: The Cables

February 7, 2024 by 18 Comments

Flexible cables and flex PCBs are wonderful. You could choose to carefully make a cable bundle out of ten wires and try to squish them to have a thin footprint – or you could put an FFC connector onto your board and save yourself a world of trouble. If you want to have a lot of components within a cramped non-flat area, you could carefully design a multitude of stuff FR4 boards and connect them together – or you could make an FPC.

Flexible cables in particular can be pretty wonderful for all sorts of moving parts. They transfer power and data to the scanner head in your flat-bed scanner, for instance.  But they’re in fixed parts too.  If you have a laptop or a widescreen TV, chances are, there’s an flexible cable connecting the motherboard with one or multiple daughterboards – or even a custom-made flexible PCB. Remember all the cool keypad and phones we used to have, the ones that would have the keyboard fold out or slide out, or even folding Nokia phones that had two screens and did cool things with those? All thanks to flexible circuits! Let’s learn a little more about what we’re working with here.

FFC and FPC, how are these two different? FFC (Flexible Flat Cable) is a pre-made cable. You’ve typically seen them as white plastic cables with blue pieces on both ends, they’re found in a large number of devices that you could disassemble, and many things use them, like the Raspberry Pi Camera. They are pretty simple to produce – all in all, they’re just flat straight conductors packaged nicely into a very thin cable, and that’s why you can buy them pre-made in tons of different pin pitches and sizes. If you need one board to interface with another board, putting an FFC connector on your board is a pretty good idea.

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Recreating The Quadrophonic Sound Of The 70s

February 6, 2024 by 23 Comments

For plenty of media center PCs, home theaters, and people with a simple TV and a decent audio system, the standard speaker setup now is 5.1 surround sound. Left and right speakers in the front and back, with a center speaker and a subwoofer. But the 5.1 setup wasn’t always the standard (and still isn’t the only standard); after stereo was adopted mid-century, audio engineers wanted more than just two channels and briefly attempted a four-channel system called quadrophonic sound. There’s still some media from the 70s that can be found that is built for this system, such as [Alan]’s collection of 8-track tapes. These tapes are getting along in years, so he built a quadrophonic 8-track replica to keep the experience alive.

The first thing needed for a replica system like this is digital quadrophonic audio files themselves. Since the format died in the late 70s, there’s not a lot available in modern times so [Alan] has a dedicated 8-track player connected to a four-channel audio-to-USB device to digitize his own collection of quadrophonic 8-track tapes. This process is destructive for the decades-old tapes so it is very much necessary.

With the audio files captured, he now needs something to play them back with. A Raspberry Pi is put to the task, but it needs a special sound card in order to play back the four channels simultaneously. To preserve the feel of an antique 8-track player he’s cannibalized parts from three broken players to keep the cassette loading mechanism and track indicator display along with four VU meters for each of the channels. A QR code reader inside the device reads a QR code on the replica 8-track cassettes when they are inserted which prompts the Pi to play the correct audio file, and a series of buttons along with a screen on the front can be used to fast forward, rewind and pause. A solenoid inside the device preserves the “clunk” sound typical of real 8-track players.

As a replica, this player goes to great lengths to preserve the essence of not only the 8-track era, but the brief quadrophonic frenzy of the early and mid 70s. There’s not a lot of activity around quadrophonic sound anymore, but 8-tracks are popular targets for builds and restorations, and a few that go beyond audio including this project that uses one for computer memory instead.

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