How to make a Bluetooth cassette for outdated equipment

Good afternoon everyone! Today I want to share with you an idea on how you can use the cassette deck of a radio or music center. Few people have such equipment left in their home, which lies as a useless burden due to the fact that magnetic recording of music on tape cassettes has sunk into oblivion.
The abundance of various boards, adapters, adapters and other devices offered on AliExpress gave me the idea of ​​using the sound-reproducing path of a cassette recorder to play music files via Bluetooth.

What do we need

• tape cassette;
  
• Bluetooth audio receiver;
  
• USB battery charging module TP4056;
  
• lithium battery 150 mAh 3.7 V;
  
• microswitch;
  
• magnetic head from an old cassette recorder.

Tools you will need are a soldering iron, a fine-toothed hacksaw (for metal), needle files or a miniature grinder.
Materials:

• Super glue;
  
• pieces of plexiglass.

Completing of the work

We take out the magnetic head from the unnecessary cassette recorder.

Carefully remove it from the fastening elements.

They are connected by resistance welding, so we simply break them off using pliers, being careful not to damage the head itself. We carefully clean the head from dirt and traces of corrosion.

To do this, you can use a solvent, then grinding paste. The result should be a blank that is smooth on all sides (except for the one where the leads are located).
We disassemble the cassette and remove the reel of film from it.


On the part of the cassette where the film is in contact with the magnetic head of the tape recorder, we prepare a socket for installing our prepared head.

To do this, carefully cut out the excess parts of the cassette and cover the seat with rectangular pieces of plexiglass.



The head socket should allow it to move freely.




The location of the head should be such that when installing our modified cassette into a cassette receiver, the magnetic heads in the tape recorder and in the cassette are in close contact with their working surfaces. They will transmit an audio signal.
The basis of the device is Bluetooth audio receiver, which receives power from lithium battery.


The battery is charged via the USB connector using module TP4056.

We mill the groove and glue the module.


We place both of these boards and the battery inside the cassette body.

We solder the signal signal to the corresponding pins of the Bluetooth board. Light-emitting diode. It will signal that the device is turned on.

Power is supplied to the device through microswitch, which is mounted in the cassette body so that when installing the cassette, the magnetic head presses on its spring element, including the audio receiver.

A piece of soft rubber is placed on the contact terminals of the magnetic head, which softens the impact of the head on the microphone and protects the head terminals from short-circuiting.



Three pins of the magnetic head are connected to terminals on the Bluetooth board (common, left, right).


When everything is soldered, press on the head and check the operation of the device before closing.

When the installation of parts is completed, we assemble the cassette. Before this, we install both film reels in place (remove the film before doing this).

This is necessary so that the cassette can securely take its place when installed in the tape recorder.

For aesthetics, you can paint the cassette with regular spray paint.



Well, that's all. Before use, charge the battery.

We insert the cassette into the tape recorder, observe the glow of the signal LED and turn on the tape recorder in playback mode.


Next, we connect to Bluetooth from the phone. We turn on our favorite pieces of music. Let's listen and enjoy.

Conclusion

Below are links to order the required components:
Bluetooth board: https://aliexpress.com
USB charging module: https://aliexpress.com
Battery 150 mAh 3.7 V: https://aliexpress.com
Microswitch: https://aliexpress.com

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