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.

26 thoughts on “Building A Cassette Deck Controller To Save A Locked Out Car Stereo

    1. Maybe someday someone explains to you the principle of fun.

      Btw. I’m the one who built this contraption. I didn’t do it to save the radio. Heck I threw away that radio (but it had an extra amplifier module that I took out and kept as spare). But I love cassettes (if that offends you, your problem not mine) and wanted to flex some diy muscles. And I had fun building it. No rhyme or reason. Just fun. And I think it’s neat.
      (for some reason the author used my name, not my handle)
      And yes, the mechanism is in great condition – it was literally unused.

      1. Fun is often the victim in the comments section. I hate those “Live, laugh, love” signs as much as the next person, but if you have to be reminded to do those 3 basic things? Go getcha one, who cares what I think? Fun can make stuff run.

  1. I’m only vaguely familiar with functional programming. Can you point to an example of how functional programming could be applied to the control of a physical device that requires user interaction such as a cassette deck?

    My brain keeps saying, “hey, this is kinda sorta not entirely unlike comparing analog computers to digital computers”.

    (I get that functional programming is performed in a digital environment, but the lack of sequential execution makes it “feel” like analog computers “feel” in my brain…”it just happens”)

    1. What the heck? I replied to a (albiet negative) comment about the virtues of functional programming, hoping to actually learn something.

      Now all of the other comments are gone.

      Admin: if all other comments are being deleted, it would make sense to go ahead and delete this one.

  2. Weird. Someone else homebrews a cool tapedeck. I comment that I also have made one that’s kinda cool but think it’s too insignificant for HaD.
    Comments be like: Hey this is great, it should be a full article!

    I finally decide to get it published on HaD
    Comments be like: Duuuurrr this sucks.

    1. Don’t let the trolls get you down man. It’s a good hack!

      I never would have thought of implementing my own tape deck automation and signal processing.

      I own exactly one cassette and I’m lazy so I’ll still never do it myself, but I’m impressed that you did 😁

    2. I hear ya! Best is to flag negative / bad comments using the “Report comment” function. They’ll go back to moderation, and we’ll take care of them.

      The internet is full of eeyores, somehow. I don’t know why.

      But the hack is great. :) Thanks for sharing!

      1. Yep. Only ever agreeing and letting “moderators” control what is apparently negative.
        Starts off all gentile, but human nature soon makes it about controlling the conversation.
        Or maybe you missed out on forums before facebook ruined the internet?

        Is this too negative? In some places it would be, and no one would see it.
        Already we people are down that slippery slope.

        Remember, one has to make a choice to take offence. Too many do.
        To silence those with an opinion which contrasts your own is not the solution.

    3. Maybe the bots have arrived. I dunno. I think its cool when people thinker and learn. Share what youve made. if an HaD editor decided its worth a shot, theill write an article and post it for you. I think thats already a sign someone finds it interesting :D

    4. It’s like a law of the internet that the loudest complainers are the ones who have no interest in the topic they are complaining about, have no intention of even reading the article they are complaining about and probably haven’t even put the effort in themselves to make anything. Their hobby is simply tearing others down.

    5. Like everyone else said, don’t listen to the haters. Basically every HaD article gets really low effort critical comments, enough that probably 80% of my comments here are from tearing into them.

  3. As much as I appreciate cassettes I never did like slimmed down slot loading decks a tiny flywheel and auto reverse etc. I would praise a decent home deck hacked to be mobile. I vaguely remember a factory deck low in the center console with a pop out door loading means. Closed loop dual capstan single direction deck a real plus. Try extracting a mangled tape from those slot loaders, or degaussing the head once in a while. Towards the CD era they forced music search feature into car decks which is fast forward with the head in contact with the tape that wears everything out fast.

    1. Yes I agree on most of that. Especially since I still record a lot of cassettes, you just can’t beat a decent deck (unless you have one of those crazy expensive super decks like Nakamichi or Revox).
      I have to disagree on the dual capstan single direction thing. If you play your C90 a hundred times through that mech, you end up with a C100. Oh wait, that’s actually a win if you record it over.
      Luckily my decks are all in good condition, I get mangled tape like once every three years and I use cassettes daily, but yes. Mangled tape in a car stereo. Been there, it’s absolutely terrible. Also you have to listen to the radio for the rest of the ride and then first extract the radio from the car, then extract the tape from the radio.

      The flywheels on this deck are decent sized and there’s two running in opposite directions so wow&flutter is certainly a lot better specced than that head preamp I built from plans off the internet.

      Years ago I was toying with the thought of designing a battery operated Reel-to-Reel that can be worn on a belt like a Walkman and doesn’t weigh half a ton.

      1. “toying with the thought of designing a battery operated Reel-to-Reel that can be worn on a belt like a Walkman”

        Like all the spy style recorders from the 60’s spy tv/film?
        Mission Impossible series springs to mind.

        1. No. I mean practical ones that play the same big reels your home recorder plays.
          Which, wearing them, would make them hilariously impractical.
          Also wow&flutter will be way off the scale. It’s just a fun little brain fart, it might get a giggle if I do it.

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