Building A Cassette Deck Controller To Save A Locked Out Car Stereo

July 9, 2024 by Lewin Day 26 Comments

Cars have had DRM-like measures for longer than you might think. Go back to the 1990s, and coded cassette decks were a common way to stop thieves being able to use stolen stereos. Sadly, they became useless if you ever lost the code. [Simon] had found a deck in great condition that was locked out, so he set about building his own controller for it.

The build relies on the cassette transport of a car stereo and a VFD display, but everything else was laced together by Simon. It’s a play-only setup, with no record, seeing as its based on an automotive unit. [Simon]’s write up explains how he reverse engineered the transport, figuring out how the motors and position sensors worked to control the playback of a cassette.

[Simon] used an Atmega microcontroller as the brains of the operation, which reads the buttons of the original deck via an ADC pin to save I/O for other tasks. The chip also drives the VFD display for user feedback, and handles auto reverse too. The latter is thanks to the transport’s inbuilt light barriers, which detect the tape’s current status. On the audio side, [Simon] whipped up his own head amplifier to process the signal from the tape head itself.

Fundamentally, it’s a basic build, but it does work. We’ve seen other DIY tape decks before, too. There’s something about this format that simply refuses to die. The fans just won’t let Compact Cassette go down without a fight. Video after the break.

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A small 3D-printed printing press with a print that says THE QUICK BROWN FOX JUMPED OVER THE LAZY BROWN DOG.

Mini 3D-Printed Press Is Sure To Make An Impression

July 4, 2024 by Kristina Panos 9 Comments

Making stamps out of potatoes that have been cut in half is always a fun activity with the kids. But if you’ve got a 3D printer, you could really step up your printing game by building a mini relief printing press.

To create the gear bed/rack, [Kevr102] used a Fusion 360 add-in called GF Gear Generator. At first this was the most finicky part of the process, but then it was time to design the roller gears. However, [Kevr102] got through it with some clever thinking and a little bit of good, old-fashioned eyeballing.

Per [Kevr102], this press is aimed at the younger generation of printers in that the roller mechanism is spring-loaded to avoid pinched fingers. [Kevr102] 3D-printed some of the printing tablets, which is a cool idea. Unfortunately it doesn’t work that well for some styles of text, but most things came out looking great. You could always use a regular linocut linoleum tile, too.

This isn’t the first 3D-printed printing press to grace these pages. Here’s one that works like a giant rubber stamp.

Everyone Needs A 1950s Signal Generator In Their Life

July 2, 2024 by Jenny List 8 Comments

At Hackaday, we comb the world of tech in search of good things to bring you. Today’s search brought up something very familiar, [Jazzy Jane] has an Advance E1 tube signal generator, the same model as the unit on the shelf above where this is being written. It’s new to her, so she’s giving it a teardown and fixing any safety issues before powering it on.

For a 70+ year old unit, the quality of these instruments was such that they remain useful and reliable to this day. Unsurprisingly a few things need looking at, such as an aged mains lead and a pair of filter caps in the power supply which haven’t aged well. These parts failed on the E1 here too, and while she’s taking the time to order appropriate replacements we have to admit to being cheapskates and robbing parts with an appropriate working voltage for ours from a nearby PC power supply.

Where this one becomes rather interesting is in an extra switch and socket. It’s a wafer switch with a load of capacitors, and the best guess is it provides some adjustability for the inbuilt audio oscillator which had a fixed frequency on stock models. This is part one of a series though, so we’re looking forward to finding out its purpose in the next installment. Take a look at the video below the break, and if that’s not enough, we seem to have had more than one piece of vintage British test equipment here of late.

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A Vintage AC Bridge Teardown

June 30, 2024 by Jenny List 2 Comments

If you ever encounter a British engineer of a certain age, the chances are that even if they use a modern DMM they’ll have a big boxy multimeter in their possession. This is the famous Avo 8, in its day the analogue multimeter to have. Of course it wasn’t the only AVO product, and [Thomas Scherrer OZ2CPU] is here with another black box sporting an AVO logo. This one’s an AC bridge, one of a series of models manufactured from the 1930s through to the late 1940s, and he treats us to a teardown and restoration of it.

Most readers will probably be familiar with the operation of a DC Wheatstone Bridge in which two resistances can be compared, and an AC bridge is the same idea but using an AC source. A component under test is attached to one set of terminals while one with a known value is put on the other, and the device can then be adjusted for a minimum reading on its meter to achieve a state of balance. The amount by which it is adjusted can then be used as a measure of the difference between the two parts, and thus the value of an unknown part can be deduced.

In the case of this AVO the AC is the 50Hz (remembering that this is a British instrument) mains frequency, and the reading from the bridge is taken via a single tube amplifier to a rectifier circuit and the meter. Inside it’s a treasure trove of vintage parts with an electrolytic capacitor that looks as though it might not be original, with a selenium rectifier and a copper oxide signal diode in particular catching our eye. This last part is responsible for some reading anomalies, but after cleaning and lubricating all the switches and bringing up the voltage gently, he’s rewarded with a working bridge. You can see the whole story in the video below the break.

Test equipment from this era is huge, so perhaps not all of you have the space for something like this. Some of us have been known to own other AVO products though.

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The Amstrad E-m@iler, The Right Product With The Wrong Business Model

June 25, 2024 by Jenny List 29 Comments

One of the joys of the UK’s Electromagnetic Field hacker camp lies in the junk table, where trash turns to treasure in the blink of an eye. This year I returned relatively unscathed from my few days rifling through the tables,but I did snag a few pieces. One of them is a wired telephone, which would be a fairly unremarkable find were it not for its flip-up LCD screen and QWERTY keyboard.

My prize is a 2002 Amstrad E-m@iler Plus, one of a series of internet-equipped telephones from the British budget electronics company. The device itself and the story behind it make for a fascinating tale of a dotcom-era Internet flop, and a piece of hardware that could almost tempt today’s hackers.

You’ve Heard Of The Dotcom Boom, But Have You Heard Of The Hardware?

In the late 1990s, everything was about the Internet, but seemingly few outside the kind of people who read Hackaday really understood what it was really about. I’ve written before on these page about how hype blinded the CD-ROM industry to the shortcomings of its technology, but while that had in reality only gripped the publishing business, the Internet hype which followed had everyone in its thrall. You’re probably familiar with the story of the dotcom boom and crash as startup companies raised millions on shaky foundations before folding when they couldn’t deliver, but in parallel with that there was also a parallel world for hardware. The future was going to be connected, but on what and whose hardware would that connection happen? Continue reading “The Amstrad E-m@iler, The Right Product With The Wrong Business Model” →

Build Your Own Core Rope Memory Module?

June 24, 2024 by Dave Rowntree 15 Comments

[Luizão] wanted to create some hardware to honour the memory of the technology used to put man on the moon and chose the literal core of the project, that of the hardware used to store the software that provided the guidance. We’re talking about the magnetic core rope memory used in the Colossus and Luminary guidance computers. [Luizão] didn’t go totally all out and make a direct copy but instead produced a scaled-down but supersized demo board with just eight cores, each with twelve addressable lines, producing a memory with 96 bits.

The components chosen are all big honking through-hole parts, reminiscent of those available at the time, nicely laid out in an educational context. You could easily show someone how to re-code the memory with only a screwdriver to hand; no microscope is required for this memory. The board was designed in EasyEDA, and is about as simple as possible. Being an AC system, this operates in a continuous wave fashion rather than a pulsed operation mode, as a practical memory would. A clock input drives a large buffer transistor, which pushes current through one of the address wires via a 12-way rotary switch. The cores then act as transformers. If the address wire passes through the core, the signal is passed to the secondary coil, which feeds a simple rectifying amplifier and lights the corresponding LED. Eight such circuits operate in parallel, one per bit. Extending this would be easy.

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Arduino + TFT = Micro Star Chart

June 20, 2024 by Al Williams 9 Comments

We always look at the round LCDs and wonder what to do with them other than, of course, a clock. Well, [shabaz] had a great idea: use it as a star map display. The project combines the Arduino, a round TFT, a GPS receiver, and some external flash memory to store data. You can get by without the GPS receiver or flash memory, but you’ll lose features if you do.

We like how he approached the problem. The project contains four major parts and he developed each part independently before integrating them into a whole. The four parts are: reading the GPS, driving the LCD, providing storage for star data, and determining the position of stars. The heavy lifting is done using some public domain code ported over. This code derives from a book called Astronomical Algorithms and uses the Yale Bright Star Catalog database.

The post mentions that the screen might well be a larger rectangular screen and we agree that would make this more usable. Now if you could cram it all into a watch, that might be different. If you want to play with the code, you can actually run the core on Linux. You’ll have to settle for a PNG output of the night sky, but that would be handy for debugging.

We have seen a star chart in a watch before. While this is more a star chart than a planetarium, we have no doubt the early planetarium builders would be suitably impressed.

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