More car audio input hacking

[Dave] pulled the head unit out of his dashboard to add an iPod input. He took a much more invasive route than the other hack we saw a few days ago. He actually patched into the audio lines going from the Dolby reader head chip to the amplifier.

The first step was to trick the deck into thinking it had a cassette inserted. He scoped an enable pin on one of the chips to discover the timing and emulated that signal using a PIC microprocessor. From there he popped off the chip that reads the tape data, patching directly into the audio out traces. This presented some noise issues when charging the iPod but [Dave] fixed that with some decoupling capacitors.

19 thoughts on “More car audio input hacking

  1. Very sad that his work bench got destroyed by a hurricane.

    Is there a “save the workbench” foundation set up to take donations?

  2. Yeah, I was going to ask if that was indeed a pair of Linstrom cutters down there in the lower right hand corner. Fantastic cutters! Will last a ligt time unless you seriously abuse them.

  3. Holy shit, I can’t believe how much those Lindstrom cutters cost! When I was with TI, they supplied me with an awesome set of cutters similar to this, but with a black tapered steel flush-cut head, hard green squarish(in cross-section) handles and a golden(if I recall correctly) silk screened logo, of which manufacturer I don’t remember, but wish I did!

  4. Hmm… Searching a little, the molded grips looked similar to the Velleman VT100 cutters(but with a flat, not glossy, finish). Unlike the Velleman cutters, though, the ones I had were not the stamped-steel type, but the milled-steel type, with a head similar to the head on the Lindstrom. I can’t believe that Google is failing me here… :)

  5. If you could find the datasheet for the tape deck control IC, it would be simple to take over the builtin controls without modifying the front buttons without the hacking he had to do.

    As for using a pic, if it’s just a delayed enable, wouldn’t using a large enough capacitor work as well?

  6. A messy workbench is a loved workbench.
    -and this one isn’t even that messy. ;)
    (not to imply that it isn’t loved)

    I’m a Snap-On man personally, but any fine quality tool is worth having when you work with them and take your work seriously, especially if you spent any time at all getting along with um, shall we say…LESS than fine quality tools.

    The hack? It’s awesome.
    I’d do the same thing if I still had a cassette player.

  7. Old hack. Guys have been doing this to stock and other stereos for a decade now.

    Most everyone in car audio circles knows about this.

  8. errr…. wouldn´t it be simpler and easier just to make a cable and connect to the AUX port behind the stereo?? Than having all this trouble for doing something with exactly the same result??

  9. Hey, I just remembered seeing this and feeling left out. I know this is old to be posting on, but maybe this will help someone else out :). I have a 2004 Subaru, and as some of you may know Subaru wasn’t too keen on the idea of AUX jacks until around 2007. I found a way to cut into the FM traces and have a fully functioning head unit with an AUX jack and no stupid “noiseless Blank cd” playing.
    Heres a link

    http://electronicsjunk.com/index.php?option=com_content&view=category&layout=blog&id=35&Itemid=60

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s