Introduction: DIY MP3 to Cassette or Instrument to Cassette Adapter

About: Electrical Engineer

A little while back I got very excited when an instructable came up that was a so-called cassette tape mp3 player, but I was quite disappointed when I found out that it was just sticking an mp3 player into a cassette body. I did some looking around and discovered that no one had figured out how to convert mp3s or even an electric instrument to a cassette format instantly and play it directly through a cassette player, and the best part? The whole thing fits easily into a pocket! Now you may be thinking... Cassettes are so old school and outdated, why would you need this? 2 reasons:
1. I can't afford an amplifier for my electric cello so I can plug it into the cassette player in the stereo and use the stereo as an amplifier
2. Old Cars like the ones my family has don't have convenient headphone jacks, so I can use this device to play my ipod through the cassette player in the car's stereo system

I did about 1 weeks research on how cassette adapters work (I didn't want to pay 20 dollars to buy one), and my versions use the same basic principles of design

It took 11 builds to get one to actually work, so in this instructable, you will see about 3 weeks worth of experimenting put into 2 versions of my diy adapter/converter

Version A is a much easier version, and the sound quality is good (it also does not require a circuit board to be made), but it does not have as good sound quality as Version B

Version B is a bit harder to build and requires basic resistor knowledge and the ability to make a circuit board, but the outcome is an amazing sound quality produced


As the steps progress, the two versions will slowly stem off from each other, so make sure to read and make sure you go to the corresponding step number of your version. Or you can try both!

Here is a video I made that shows the capabilities of the device. WATCH IT!

Step 1: Finding the Right Cassette Tape for the Project

The best possible kind that you can find is either one from a band that you hate or wouldn't mind never listening to again, or one with screws. Screws make life a lot easier when it comes to assembling the whole thing. If you can't find one with screws, however, you should be fine. For mine, I used one with Screws for version B and one without for version A.

A word of caution, TDK tapes do NOT have screws.

Step 2: Materials

You need:
A lego plate that you don't mind cutting and destroying
Some old headphones
Glue (Hot Glue and Super Glue)
Some wire (As thin as you can get)
A magnetic head (Coincidentally, I found one in one of my previous projects that used a sony walkman) -these can be found in any cassette player because they are originally used for reading cassette tapes... UNTIL NOW!
Either a pen or a small spring
Resistors if you are doing version B
A file
Clear tape

Step 3: Preparing the Casing

Open the casing either by taking out the screws or cutting it open
You can discard the small piece of metal and cushioning found pressed against the tape and all of the tape surrounding the wheels

This is the fun part. Watch the video to see how to take the tape off the cool way.

Next you need to smooth out the bottom of the tape.

Step 4: Assembly Part 1

Solder wires to the magnetic head
Here are your options:
If your magnetic head comes with 4 Solder points:
Either solder a wire to each one or solder 1 wire to every other one, making sure that they are on opposite sides
If your magnetic head comes with three solder points:
Solder 1 wire to the single side and 1 wire to one of the doubles, or one to a single and 1 to each double
If your magnetic head comes with 2 solder points:
1 wire for each point

Step 5: Assembly Part 2

Start by creating a spring mechanism for the magnetic head
So why do we need a spring mechanism? Well, in order to make sure that the contacts from the reader and this device are always touching, a spring mechanism is used to keep the magnetic heads together.

I ended up using a spring mechanism that I found in my lego box, but any spring mechanism should work fine. You can see a picture of it on the previous step. (It's the white thing)

Step 6: Headphone Preparation

Clip off the buds and expose the wires from each side.
You should have 1 gold wire and one colored wire from each bud
You will need to use a flame to burn the coating off

Step 7: Now Things Split Up

Split it up
Split it up! :)
                        IF YOU ARE DOING VERSION B, GO TO STEP 8


1. Build the circuit shown in the first picture
How I made my circuit:
I used a piece of plastic and some copper tape. I placed the copper tape onto the plastic and drilled holes where the components would come through, then I soldered everything together. If you do this, do it in a well ventilated area.
2. Connect it to the spring mechanism and magnetic head and glue it all to the inside of the cassette tape
3. Cut the top of the cassette body to allow better sliding of the magnetic head
4. Finish the casing of the cassette tape
5. DONE!

Step 9: Finishing It Up(VERSION A)

All that's left for you to do is solder the headphone wires up to the magnetic head and then glue the spring mechanism to the casing.
First, solder both gold headphone wires to one side of the magnetic head and the colored wires to the other side.
Then glue the spring mechanism with the magnetic head attached to the casing. Make sure the magnetic head is almost even with the end of the casing. Seal everything up and split open the top of one side of the casing for easier sliding of the magnetic head. Now all you have to do is file a little slit in the cassette tape case for the headphone wires to stick out and then you are done! You can even use the case as a stand for your ipod when you are using this device!

Step 10: Troubleshooting Part 1

The cassette player keeps flipping the tape over:

I made a quick sketch of something that might help your situation- It allows for uni-directional turning of the wheels, making the tape unable to be flipped over (in theory anyway)

Step 11: Troubleshooting Part 2

The music is not playing:

There are a few things that could be wrong:
1. The tape has to be actually playing
2. You may need to flip the tape over
3. Make sure your music playing device is actually playing (I had to include this since I had trouble with this one)
4. If all else fails either check the circuit or go for the simpler version

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