A Non-Musical Use Case For 8-Track

There was a time in the not-too-distant past when magnetic tape was the primary way of listening to and recording audio. Most of us are familiar with the cassette tape, a four-track system that plays first one side of the tape, then the other. There was the eight-track tape as well which did not have quite as much popularity or longevity but did have a few interesting features that [Serial Hobbyism] took advantage of to make an interactive game.

The defining feature of the eight-track system, beyond the obvious eight tracks on the tape, is that the tape runs in a continuous loop, never needing to be stopped or flipped over. Instead, four buttons select pairs of the eight tracks, moving a head immediately to make the switch on-the-fly. [Serial Hobbyism]’s game plays a trivia-style audio recording and asks the player to answer questions by pushing one of the four “program” buttons to switch tracks. If the correct track is selected, the recorded audio congratulates the player and then continues on with the game. Likewise, if an incorrect track is selected, the recording notes that and the game continues.

Another interesting feature of this game is that it can be played without modifying an eight-track player, as the selectable tracks are a core function of this technology. They can be used in a similar way as cassette tapes to store computer data and a data recorder similar to the eight-track system was used on the Voyager space probes, although these only bear a passing resemblance.

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A person putting a screw into a CNC spoil board on the left of the image. Their drill is chartreuse and black. Clamps hold a rectangular board down at all four corners. The spindle of the CNC is just visible on the right hand side of the image.

Workholding Options For The Beginner CNC Operator

Designing a file to cut on a CNC is only part of the process. You also have to keep it in place while the machine does its work. [Garrett Fromme] walks us through five different work holding techniques.

Since every project is different and stock material can vary from thin veneer to much larger pieces, there’s no one right work holding method for every project, and not all methods are applicable to all materials. A vise is great for small projects that need to be held very securely and won’t be damaged, vacuum tables can make switching pieces quick in a production environment, fasteners will hold a piece securely at the expense of your spoil board, clamps are fairly versatile but fiddly to setup, and tape and CA glue are quick but require more consumables.

[Fromme] does a quick demonstration of setups with these different methods and their limitations, which is a great place to start for the beginner CNC operator. Just like 3D printers, CNCs are a far cry from the replicators in Star Trek that can automagically create what you ask it to, but proper workholding lets you waste less material and operate the machine more safely.

Our own [Elliot Williams] had a look at how CNCs aren’t as automated as you think. If you do need some CNC clamps, you might try these printable parametric clamps, or if you want something more beautiful, give these metal toe clamps a go.

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

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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Building A Tape Echo In A Coke Can Tape Player That Doesn’t Really Work

Back in the 1990s, you could get a tape player shaped like a can of Coca Cola. [Simon the Magpie] scored one of these decks and decided to turn it into a tape echo effect instead. It didn’t work so well, but the concept is a compelling one. You can see the result in the video below.

The core of the effect is a tape loop, which [Simon] set up to loop around a pair of hacked-up cassette shells. This allows him to place one half of the loop in the Coca-Cola cassette player and the other half in a more conventional desktop tape deck. A 3D-printed bracket allows the two decks and the tape loop to be assembled into one complete unit.

The function is simple. The desktop tape deck records onto the loop, with the Coca-Cola unit then playing back that section of tape a short while later. Hey, presto — it’s a tape delay! It’s super lo-fi, though, and the tape loop is incredibly fragile.

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3D Printing A Cassette Is Good Retro Fun

The cassette is one of the coolest music formats ever, in that you could chuck them about with abandon and they’d usually still work. [Chris Borge] recently decided to see if he could recreate these plastic audio packages himself, with great success.

He kicked off his project by printing some examples of an open source cassette model he found online. The model was nicely accurate to the original Compact Cassette design, but wasn’t exactly optimized for 3D printing. It required a great deal of support material and wasn’t easy to customize.

[Chris] ended up splitting the model into multiple components, which could then be assembled with glue later. He then set about customizing the cassette shells with Minecraft artwork. Details of the artwork are baked into the model at varying heights just 1/10th of the total layer height. This makes it easy to designate which sections should be printed with which filament during his multi-colored print. And yet, because the height difference is below a full layer height, the details all end up on the same layer to avoid any ugly gaps between the sections. From there, it’s a simple matter of transferring over the mechanical parts from an existing cassette tape to make the final thing work.

It’s a neat trick, and the final results are impressive. [Chris] was able to create multicolored cassettes that look great. It’s one of the better uses we’ve seen for a multi-colored printer. This would be an epic way to customize a mixtape for a friend!

We’ve seen some great 3D printed cassettes before, too, like these retro reel-to-reel lookalikes.

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Super-Portable, Tunable VHF Antenna

Ham radio is having a bit of a resurgence these days, likely due to awards programs like Parks on the Air (POTA) and Summits on the Air (SOTA), which encourage amateur radio operators to head outside and “activate” at various parks and mountaintops. For semi-mobile operations like this, a low-power radio is often used, as well as other portable gear including antennas. In the VHF/UHF world, the J-pole is a commonly used antenna as well, and this roll-up tunable J-pole antenna is among the most versatile we’ve seen.

The antenna uses mostly common household parts which keeps the cost down tremendously. The structure of the antenna is replacement webbing for old lawn chairs, and the conductive elements for the antenna are made out of metallic HVAC tape which is fixed onto the chair webbing after being cut to shape. The only specialized parts needed for this is a 3D printed bracket which not only holds the hookup for the coax cable feeding the antenna, but is also capable of sliding up and down the lower section of the “J” to allow the antenna to be easily tuned.

As long as you have access to a 3D printer, this antenna is exceptionally portable and pretty easy to make as well. Although VHF and UHF aren’t too popular for POTA and SOTA, portable equipment like this for the higher frequency bands is still handy to have around when traveling or operating remotely. With the antenna situation sorted out, a DIY radio that can make use of it might be in order as well.

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A Quick And Stealthy Mobile Slot Antenna From Copper Tape

[Ben Eadie (VE6SFX)] is at it again with the foil tape, and this time he’s whipped up a stealthy mobile sunroof antenna for the amateur radio operator with the on-the-go lifestyle.

You may recall [Ben]’s recent duck tape antenna for the 70-cm ham band, an ultra-lightweight design that lends itself to easy packing for portable operation. The conductors in that antenna were made from copper foil tape, a material that’s perfect for all sorts of specialized applications, like the slot antenna that he builds in the video below. In the ham world, slot antennas are most frequently seen cut into the main reflector of a direct satellite dish, often in hopes of avoiding the homeowner association’s antenna police. Even in the weird world of RF, it’s a strange beast because it relies on the absence of material in a large planar (or planar-ish) conductive surface.

Rather than grabbing an angle grinder to make a slot in the roof of his car, [Ben] created a “virtual” slot with copper tape on the inside of his car’s sunroof. His design called for a 39″ (0.99-m) slot, so he laid out a U-shaped slot to fit the window and outlined it with copper foil tape. His method was a little complex; he applied the copper tape to a transparent transfer film first, then stuck the whole thing to the underside of the glass in one go. It didn’t quite go as planned, but as he learned in the duck tape antenna, the copper tape makes it easy to repair mistakes. A BNC connector with pigtails is attached across the slot about 4″ (10 cm) up from the end of one of the short legs of the slot; yes, this looks like a dead short, but such are the oddities of radio.

Is it a great antenna? By the numbers on [Ben]’s NanoVNA, not really. But any antenna that gets you heard is a good antenna, and this one was more than capable in that regard. We’ll have to keep this in mind for impromptu antennas and for those times when secrecy is a good idea.

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