RIP Lou Ottens, Developer Of The Compact Cassette And More

March 12, 2021 by Jenny List 30 Comments

It’s with sadness that we note the passing at the age of 94 of the long-time Phillips engineer Lou Ottens, who is best known as the originator of the Compact Cassette audio tape format that was so ubiquitous through the later decades of the 20th century. Whether you remember cassettes as the format for 8-bit software, for teenage mixtapes on a Walkman, they began life at his hands in the early 1960s at the Phillips factory in Hasselt, Belgium.

Through a long career with the Dutch electronics company, he was responsible either directly or in part for a string of consumer electronic devices that we would see as ubiquitous over the latter half of the century. Before the cassette he had developed the company’s first portable reel-to-reel tape recorder, and in the 1970s while technical director of their audio division he led the team that would develop the CD. He was reported as saying that his great regret was not beating Sony to the development of the miniature cassette player that would be sold as the Walkman, but we’d suggest that the Walkman would not have been possible without the cassette in the first place.

So next time you handle a cassette tape, spare a thought for Lou, an audio engineer whose work permeated so much of the last half-century.

Thanks [Carl] for the tip.

Images: Lou Ottens by Jordi Huisman CC BY-SA 4.0 and “An early Phillips cassette recorder” by mib18 CC BY-SA 3.0

IKEA Shelf Becomes Kid Friendly MP3 Player

February 12, 2021 by Lewin Day 17 Comments

IKEA’s flatpack furniture has long been popular among makers for its modular nature and low cost, making it ideal for whacky experiments and custom builds. [Claus] is one such person, and built a fun MP3 player for his kids out of a basic LACK shelf.

The music is handled by an NodeMCU ESP8266, working in concert with a VS1053 audio board. The VS1053 is a highly capable chip, capable of decoding a variety of raw and compressed audio formats as well as MIDI, but here it’s used to read SD cards and play MP3s. An RC522 is used to read RFID cards to trigger various tracks, allowing kids to choose a song by simply placing a tag on the shelf. A cheap PAM8302 amplifier and speaker are used to output the music. All the hardware is installed neatly inside the LACK shelf, an easy job thanks to the primarily cardboard construction.

RFID cards are more fun than we normally give them credit for, and we’ve seen a few builds along similar lines to this one. Video of [Claus’s] child rocking out after the break.

Continue reading “IKEA Shelf Becomes Kid Friendly MP3 Player” →

Adding Remote Control To An Old Stereo

January 29, 2021 by Lewin Day 17 Comments

Sometimes, the best hifi gear is the gear you’ve already got. This is particularly the case in the cassette world, as high quality decks are long out of production. [Nick] liked his current rig, but wanted to be able to use it with a remote from across the room. Naturally, he set to hacking the feature in.

The cassette deck in question, a Yamaha K-220, was old enough to lack a remote, but thankfully new enough to use a computer-controlled tape transport. This meant that the basic features of play, stop, rewind and fast forward can all be controlled with simple digital buttons rather than mechanical ones. This made it easy to interface an ATmega328P to the stereo’s original circuitry. Digital IO pins are hooked up to the buttons, held as high-impedance inputs most of the time, only toggling to ground when necessary to trigger a button press. It was then a simple job to hook up an IR receiver to the chip and program it with some Arduino libraries to work with a typical stereo remote control [Nick] had laying around.

It’s a tidy build, and with more cool cassette releases coming out every year, we’re sure [Nick]’s going to put some miles on the setup. If you find IR too cumbersome though, you can go a step further and replace it with a web app instead. If you’ve been tinkering with similar things in your own workshop, be sure to drop us a line!

Listening To Long Forgotten Voices: An Optical Audio Decoder For 16 Mm Film

January 2, 2021 by Danie Conradie 20 Comments

Like many of us, [Emily] found herself on COVID-19 lockdown over the summer. To make the most of her time in isolation, she put together an optical audio decoder for old 16 mm film, built using modern components and a bit of 3D printing.

It all started with a broken 16 mm projector that [Emily] got from a friend. After repairing and testing the projector with a roll of film bought at a flea market, she discovered that the film contained an audio track that her projector couldn’t play. The audio track is encoded as a translucent strip with varying width, and when a mask with a narrow slit is placed over the top it modulates the amount of light that can pass through to a light sensor connected to speakers via an amplifier.

[Emily] used a pair of razor blades mounted to a 3D printed bracket to create the mask, and a TI OPT101 light sensor together with a light source to decode the optical signal. She tried to use a photoresistor and a discrete photodiode, but neither had the required sensitivity. She built a frame with adjustable positions for an idler pulley and the optical reader unit, an electronics box on one end for the electronic components, and another pulley attached to a stepper motor to cycle a short loop of the film.

Most of the projects we see involving film these days are for creating digital copies. You can digitize your old 35 mm photo film using a Raspberry Pi, some Lego pieces, and a DSLR camera, or do the same for 8 mm film with a 3D printed rig. Continue reading “Listening To Long Forgotten Voices: An Optical Audio Decoder For 16 Mm Film” →

Building Distributed Mode Loudspeakers With Plywood

December 16, 2020 by Lewin Day 18 Comments

Distributed-mode loudspeakers work rather differently from the typical drivers used in 99% of applications. Instead of using piston-like motion to create sound waves, they instead rely on exciting an entire panel to vibrate and thus produce sound. [JGJMatt] decided to build a pair of bookshelf-sized units, with great results.

The build begins with a pair of 44mm DML exciters, readily available online. These had to be modified to remove their stock metal mounting plates that degraded the sound output in early tests. Instead, 3D printed pieces were used to mount the exciters to the 3mm plywood boards, which were lasercut to act as the main DML panels. Additionally, whizzer cones were fitted to the panels in an effort to further boost the high frequency response of the speakers. The speaker stands are assembled out of more 3D printed pieces and aluminium rods, giving a clean, modern look to the final product.

The performance of the speakers is admirable based on the test video, though [JGJMatt] notes that they should be paired with a subwoofer in use as the DML units do not readily produce frequencies below 100Hz. We’ve seen similar builds before on a larger scale, too. Video after the break.

Continue reading “Building Distributed Mode Loudspeakers With Plywood” →

Auto Tuning For A Vintage Stereo

December 13, 2020 by Jenny List 8 Comments

In 1984 there weren’t many ways to listen to high-quality music, so an FM tuner was an essential part of any home hi-fi system. The Pioneer TX-950 picked up by [The Curious Lorenz] would have been someone’s pride and joy, with its then-cutting-edge microprocessor control, digital PLL tuning, and seven-segment displays. Astoundingly it doesn’t have an auto-tuning function though, so some work to implement the feature using an ATtiny85 was called for.

A modern FM tuner would be quite likely to use an all-in-one tuner chip using SDR technology under the hood, but this device from another era appears to be a very conventional analog tuner to which the PLL and microprocessor have been grafted. There are simple “Up” and “Down” buttons and a “Station tuned” light. One might imagine that given these the original processor could have done autotune. At least the original designers were kind enough to provide the ATtiny with the interfaces it needs. Pressing either button causes it to keep strobing its line until the “Station tuned” line goes high, at which point it stops. It’s an extremely simple yet effective upgrade, and since the ATtiny is so small it’s easily placed on top of the original PCB. The result is an ultra-modern tuner from 1984, that’s just that little bit more modern than it used to be.

If you don’t have a vintage FM radio, you can always build its modern equivalent.

An Epic Quest For A Motorized Volume Knob

December 7, 2020 by Tom Nardi 24 Comments

[Haris Andrianakis] likes his Logitech Z623 sound system. He likes it a lot. Which is why he was willing to hack in his own remote volume control rather than just get a new pair of speakers. But he certainly didn’t make things easy on himself. Rather than trying to tap into the electronics, he decided to take the long way around and motorize the volume knob.

The belt drive looked great, but didn’t work.

The idea seemed simple enough. Just drill a hole through the PCB behind the knob’s potentiometer, attach some kind of extension to the axle, and turn it with a small servo. Modifying the PCB and potentiometer went well enough, but the trouble came when [Haris] actually tried to turn the thing.

Attaching the servo directly to the axle worked, but it made turning the knob by hand extremely difficult. His next idea was to add a small belt into the mix so there would be some slip in the system. But after designing a 3D printed servo mount and turning custom pulleys on the lathe, it ended up having too much slip, and the knob didn’t always move when the servo turned.

He then swapped out the servo for a small stepper motor. The motor was easy enough to spin when powered down, but didn’t have quite enough torque to turn the knob. He tried with a larger stepper motor that he salvaged from an old printer, but since he could only run it at half the recommended 24 VDC, it too had a tendency to skip steps.

After experimenting with some 3D printed reduction gears, [Haris] finally stumbled upon the 28BYJ-48. This small stepper with an integrated gearbox proved to be the perfect solution, as it had enough muscle to turn the knob while at the same time not restricting its movement when powered down. The rest of the project was relatively easy; with a DRV8825, an ESP8266, and an IR receiver, he’s able to spin the stepper with his TV’s remote. A simple web page running on the ESP8266 even allows him to control volume over the network with his smartphone. Based on similar projects we’ve seen, he could probably add support for HDMI CEC as well.

[Haris] says you shouldn’t follow his example, but we’re not so sure. He kept going when others would have given up, and the engineering and thought that went into each attempt is certainly commendable. Even if he hadn’t ultimately gotten this project working, we’d still say it was a valiant hack worthy of praise.