Scavenging CDs For Flexible Parts

CDs are becoming largely obsolete now, thanks to the speed of the internet and the reliability and low costs of other storage media. To help keep all of this plastic out of the landfills, many have been attempting to find uses for these old discs. One of the more intriguing methods of reprurposing CDs was recently published in Nature, which details a process to harvest and produce flexible biosensors from them.

The process involves exposing the CD to acetone for 90 seconds to loosen the material, then transferring the reflective layer to a plastic tape. From there, various cutting tools can be used to create the correct pattern for the substrate of the biosensor. This has been shown to be a much more cost-effective method to produce this type of material when compared to modern production methods, and can also be performed with readily available parts and supplies as well.

The only downside to this method is that it was only tested out on CDs which used gold as the conducting layer. The much more common aluminum discs were not tested, but it could be possible with some additional research. So, if you have a bunch of CD-Rs laying around, you’re going to need to find something else to do with those instead.

Thanks to [shinwachi] for the tip!

Retrotechtacular: 1990s CD Mastering Fit For A King

Before it was transformed into an ephemeral stream of ones and zeroes, music used to have a physical form of some kind. From wax cylinders to vinyl discs to tapes of various sizes in different housings and eventually to compact discs, each new medium was marketed as a technological leap over the previous formats, each of which justified incrementally more money to acquire.

But that’s the thing — each purchase resulted in you obtaining a physical item, which had an extensive manufacturing and distribution process behind it. And few artists demanded more manufacturing effort than Michael Jackson in his heyday, as revealed by this in-depth look at the CD manufacturing process for The King of Pop’s release of the HIStory double-disc set in 1995.

The video was produced as sort of a love letter to Michael from the staff and management of the Sony Music disc manufacturing plant in Pittman, New Jersey. The process is shown starting with the arrival of masters to the plant, strangely in the form of U-matic videocassettes; the 3/4″ continuous loop tape was normally used for analog video, but could also be used for recording digital audio. The digital audio is then sent for glass mastering, which is where the actual pits are created on a large glass disc under cleanroom conditions. In fact, much of the production process bears a strong similarity to semiconductor manufacturing, from the need for cleanrooms — although under less stringent conditions than in a fab — to the use of plasma etching, vapor deposition, and metal plating operations.

Once the master stampers are made, things really ramp up in replication. There the stamper discs go into injection molding machines, where hot polycarbonate is forced against the surface under pressure. The copies are aluminized, spin-coated with UV-cure lacquer, and sent on down the line to testing, screen printing, and packaging. Sony hired 40 extra full-time workers, who appear to have handled all the tedious manual tasks like assembling the jewel cases, to handle the extra load of this release.

As cheesy as this thank-you video may be, it was likely produced with good reason. This was a time when a Michael Jackson release was essentially a guarantee of full employment for a large team of workers. The team was able to produce something like 50,000 copies a day, and given that HIStory sold over 20 million copies, that’s a lot of workdays for the good folks at Pittman.

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A MiniDisc Optical Head Has A Few Surprises Up Its Sleeve

There was an odd era at the start of the 1990s when CDs had taken the lead from vinyl in pre-recorded music, but for consumer recordable formats the analogue cassette was still king. A variety of digital formats came to market to address this, of which Sony’s MiniDisc was the only one to gain significant traction outside the studio. These floppy-disk-like cartridges held a magneto-optical medium , and were the last word in cool until being swept away around the end of the decade by MP3 players. Hackaday alum [Nava Whitford] has disassembled a MiniDisc optical head to document how the physical part of the system worked.

The first surprise is that the MiniDisc was in fact a two-in-one system. The recordable discs were magneto-optical and wrote data by heating the disc with a laser under a magnetic field, while the pre-recorded discs used etched pits and lands in a similar way to the CD. Remembering the technical buzz around the system back in the day, either we audio enthusiasts glossed over this detail, or more likely, Sony’s PR did so to emphasize the all-new aspect of the system.

The teardown goes in depth into how while like a CD player there is a photodiode array involved, the extra components are a diffraction grating and a Wollaston prism, an optical component which splits polarized light into two beams. The photodiode array is more complex than that of a CD player, it’s speculated that this is to detect the different polarized beams as well as for the task of maintaining alignment with the track.

All in all this is a rare chance to look at something we know, but which few of us will probably have dismantled due to its relative scarcity compared to CD mechanisms. Definitely worth a look. Meanwhile if this era is of interest, take a look at a Hack Chat we did a while back looking at the MiniDisc’s would-be competitor.

RIP Lou Ottens, Developer Of The Compact Cassette And More

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

 

Mini CNC Mill Goes Horizontal To Reuse CD Drives

Here at Hackaday, we pride ourselves on bringing you the freshest of hacks, preferably as soon as we find out about them. Thanks to the sheer volume of cool hacks out there, though, we do miss one occasionally, like this e-waste horizontal CNC mill that we just found out about.

Aptly called the “CDCNC” thanks to its reliance on cast-off CD drive mechanisms for its running gear, [Paul McClay]’s creation is a great case study on what you can do without buying almost any new parts. It’s also an object lesson in not getting caught in standard design paradigms. Where most CNC mills mount the spindle vertically, [Paul] tilted the whole thing 90 degrees so the spindle lies on its side. Moving it back and forth on a pair of CD drive mechanisms is far easier than fighting gravity for control, and as a bonus the X- and Y-axes have minimal loading too. The video below shows the mill in action, and it’s easy to see how the horizontal arrangement really helps make this junk bin build into something special.

We think [Paul] did a great job of thinking around the problem with this build, and we’re glad he took the time to tip us off. Apparently it was the upcoming CNC on the Desktop Hack Chat that moved him to let us know about this build. Here’s hoping he drops by for the chat and shares his experience with us.

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Continuous Integration: What It Is And Why You Need It

If you write software, chances are you’ve come across Continuous Integration, or CI. You might never have heard of it – but you wonder what all the ticks, badges and mysterious status icons are on open-source repositories you find online. You might hear friends waxing lyrical about the merits of CI, or grumbling about how their pipeline has broken again.

Want to know what all the fuss is about? This article will explain the basic concepts of CI, but will focus on an example, since that’s the best way to understand it. Let’s dive in. Continue reading “Continuous Integration: What It Is And Why You Need It”

Creating A Sonic Landscape With Glitching CD Player

CDs were a great advancement in audio quality when they were first put on the market. There’s no vinyl-style degradation of the medium if it’s played over and over, and there’s no risk of turning them into a giant pile of ribbon while rewinding like a cassette tape. The one downside was that if you were to take them on the move you needed special hardware and software to prevent the inevitable skipping. If you look at the skipping not as a downside, though, but as a way to produce interesting music, you might end up with a pretty unique piece of hardware.

[Dmitry] is known for his interesting art installations, and the latest one uses parts from three 1988 Sony D2 CD players that have been reassembled in order to take advantage of a skipping and glitching CD. The modified equipment is able to play during pause or rewind thanks to a processor modification, and can also change the rotational speed of the disc. There are other pieces of hardware included for more fine control of glitching and skipping of the audio being read off of the CD.

The new device functions as a working musical instrument, although [Dmitry] says that it is more useful for deconstructing the information stored on the disc, and exploring the medium itself. Of course if you have enough motivation, you can find sounds from almost anywhere on (or in) the planet too.