Repurposing a cassette tape into an MP3 player

[Noon]

To start off with, I'd like to point out that I am a complete newbie when it comes to electronics (compared to an electrical engineer or hobbyist.) The most experience I have with electronics is that I have built and maintained a bare-bones PC, which more or less means that I have the ability to use a screwdriver and the skill to plug things in. I'm also relatively new to this forum, so I apologize in advance if I'm posting in the wrong sub-forum or in the wrong format. I've been watching the EEVBlog for about a year or two now out of sheer interest, but have never really done any projects on my own.

So recently I've stumbled into looking at cassette tape designs and I immediately went into a hipster trance. Basically, I want to repurpose a cassette tape into an MP3 player that will essentially still work in a car tape deck. I've googled around looking to see if this sort of thing has been commercialized and found this cheap, mass-produced looking thing. Instead of giving into this option, I would love to at the very least attempt to make something similar that is (hopefully) a tad more high-quality.

As I'm no expert on this matter, this 'project' will more or less just be me modding a cassette tape. I won't be creating circuit board schematics or basically doing this all from scratch. I figure the process will be extremely similar to this guy's tutorial on similar subject matter.

Essentially what I plan on doing looks a little like this:

• Hollowing out a cassette tape (preferably one with some heft to it. One made of metal or a sturdy/high quality plastic maybe?)
• Buying a cassette-to-audio jack adapter and removing the magnetic head, attached PCB, and cable.
• Fitting the previously removed equipment into the new cassette tape.
• Buying a fairly small MP3 player (preferabley something that uses SDHC cards), gutting the circuit board & battery out of it and placing it in the new cassette tape so that the SDHC card port is near a wall of the cassette for easy access later on.
• Cutting holes in the side of the cassette so that the SDHC port, mp3 audio jack, mp3 charging port, buttons (play, next track, stop, etc), and the audio cable connected to the magnetic head can be outside of the cassette-case.
• Secure all of the circuit boards and other miscellaneous things down (Screws, glue, tape?)
• Finally screwing the cassette back together and pray that everything works.

I'm most likely over-simplifying things, so please feel free to criticize me and show me how things should be done. This is all concept, so I have little to none of any of the materials. I've come here mostly for guidance for this childish endeavor I may partake in, so I appreciate all input and help. I'd particularly appreciate any suggestions for materials I could use such as small MP3 players I could use. If you want to remix this concept entirely, feel free to do so. My plan I listed earlier is most likely hasty and unintelligent, so any revisions are extremely appreciated. If this task evidently becomes to heavy for someone as inexperienced as I am, I will probably give in and buy the cheap, mass-produced version.

[miguelvp]

Use the cassette driver to turn a small generator on both reels since it's probably a reversible player that charges the mp3 player's battery, leave the magnetic pickup to play the audio.
If you want to get creative, detect the speed of the fast forward or reverse to select the next/previous song, also detect if the motor is running to play or pause.
Couple of prisms to bring the lcd screen output to the visible side of the cassette edge. Edit, or one prism if the screen is backwards to begin with.
Make sure there is an on/off switch so the battery doesn't drain while not playing, or at least use an mp3 player that goes to sleep.
Add extra buttons on the edge for the other controls for manual operation.

Edit: that way, you don't have to modify the tape player at all.

[Skimask]

Already been done...years ago...

http://www.amazon.com/Music-Player-Cassette-Adapter-Reader/dp/B00CK5L494

[miguelvp]

Already been done...years ago...

http://www.amazon.com/Music-Player-Cassette-Adapter-Reader/dp/B00CK5L494

OP already linked that (under cheap mass-produced looking thing), he wants something better

[Noon]

Those are some pretty good ideas Miguel, I appreciate it. The generator sounds a little complicated, but I imagine that I could also use a car's 12v port for charging as well.

Already been done...years ago...

http://www.amazon.com/Music-Player-Cassette-Adapter-Reader/dp/B00CK5L494

I am aware of this, in fact I linked to this very amazon product in my original post.

[Skimask]

http://www.amazon.com/Music-Player-Cassette-Adapter-Reader/dp/B00CK5L494

I am aware of this, in fact I linked to this very amazon product in my original post.
[/quote]
Yep, sure did.  I see it now on this screen.  Didn't make out the underline-link on the tablet...

[SirNick]

Cool idea, I dig the hipster appeal. 

A cassette shell is pretty tight, so your original plan for just a file player and the magnetic head is probably a good place to start.  Generators et all would be a nifty trick, but good luck cramming all of that in the space you have available!  I think you're on the right track as it is.  Give it a shot.  The parts are cheap.

Random thoughts and suggestions:

You might consider using a flash-based player rather than something that takes cards.  Of course, that depends on internal capacity and how often you'll want to exchange content, but not having to bother with removable media would be kind of nice.  More flexibility with internal layout, fewer modifications to the case, etc.  You would need to find a suitable place for the USB jack though.  Maybe inside one of the wells at the bottom where the pinch rollers go?  (Make sure it's flush with the inside wall to avoid obstructing the player mechanics -- and make sure the plug fits in there.)

If you don't need USB, put a small DC barrel jack in the little tab recess at the top corner of the shell.  Nice and clean.

[Noon]

I'll certainly consider a flash-based MP3 player over an SD card one, it would certainly be a lot simpler to transfer files and such. I was initially gravitating towards storage card based players because of the flexible storage capacity, but easy to access flash memory is an even bigger pro. I'll probably be spending a good chunk of time finding an MP3 player which can fit inside a cassette shell and features the proper ports and all that sort of stuff. The hardest thing about this to me seems to be how to manage buttons (mostly just play and stop, a 'next track' or whatever else the player supports would be nice as well) on the case. I'll probably come up with something or the other once I have everything in front of me.

With that said, I'm going to start gathering some materials and hopefully begin this project soon

[miguelvp]

USB for charging and transfering music, if low in charge then one of those cig lighter usb chargers will bring it back to live.
for controls they make some wireless (battery operated and not rechargable) controls for radios. The attach to the steering wheel so it has easy access and causes no distraction from the road.
You don't want tiny buttons on the cassette specially since some tape players take in the whole thing (so external power might not be feasable at all while operating, nor for the display, so maybe a disable display to save on battery).

The thing is that there are other options out there, like mp3 players that broadcast FM so you car can pick it up, then you don't need a thing.

[Lee697]

Who still has a cassette deck anyway?? 
I haven't seen one since the turn of the century I'd estimate....

[Mr.B]

Another pitfall is the internal mechanical interlink requirement.
Refer to the picture of the inside of the "cheap, mass-produced looking thing".
The drive wheel must turn the other wheel in the cassette or the player thinks the tape is at the end.
Depending upon the model/age of cassette player it will either stop or try to reverse.
If it reverses it will not be able to detect the tape movement either because there is no mechanical interlink.

I don't want to pour water on your idea, but you are going to have a mission to fit everything in... including the mechanical interlink.

[miguelvp]

Who still has a cassette deck anyway?? 
I haven't seen one since the turn of the century I'd estimate....

Some cars had them past the turn of the century, not sure they still do. (I'm looking at you VW)

[Noon]

I don't want to pour water on your idea, but you are going to have a mission to fit everything in... including the mechanical interlink.

You make a really good point, it will definitely be a tight fit. I'm assuming the simplest form of this interlink looks like this, so I would more or less be betting on these gears being thin/short enough for me to squeeze the circuit board on top or under those gears...

Some cars had them past the turn of the century, not sure they still do. (I'm looking at you VW)

Yep, the VW Golf MK4's radio came standard with a tape deck (to my knowledge.) The MK4 was produced until around 2004 according to wikipedia, and I'm pretty sure the MK5 didn't carry a tape deck.

[Mr.B]

...so I would more or less be betting on these gears being thin/short enough for me to squeeze the circuit board on top or under those gears...

The gears at the bottom right that come in contact with the captsin and pinch roller occupy all the space IIRC.
There may be a little bit of room where the other gears are, but I doubt enough for a PCB, and definitely not a PCB populated with anything.

Good luck anyway.

[poorchava]

you could hook up the mp3 player output to the input of power amplifier in the casette player. Just place the SD card slot inside the casette compartment.

[VK5RC]

While doing the project will be a bit of fun,  the quality may be limited by the transfer process of magnetic head to head,  it was always the weak link in cassettes. 
Have you tried the Amazon cheap one,  getting it and modify it to improve its quality  may provide also some fun.

[SirNick]

I don't know for a fact, but I would hope the magnetic interface would sound better than the ultra low power FM broadcast adapters.  IME, those are horrible.  Usually can't even manage stereo -- probably from the receiver believing it's a low-strength and/or distant station, and just trying to optimize the primary carrier as much as possible.

OP:  Would 3D printing a custom tape shell be a possibility?  (Just curious -- might help to get the most out of the internal space.)

[Noon]

OP:  Would 3D printing a custom tape shell be a possibility?  (Just curious -- might help to get the most out of the internal space.)

While that would be pretty awesome/optimal, I don't have a 3D printer nor do I have access to one. If there was some sort of online service that printed those 3D files, that would be a start, but even then I've never touched 3D modelling programs in my life.