I recently found my dad's old cassette player in my home. It was still looking good in condition and then i thought of doing something with that. Along with my old and broken bluetooth speaker, i converted the cassette player into bluetooth boombox.
I share here in this instructable about my work.
Step 1: Open the Player..
Open the cover slowly and you can see many things inside
- A pair of speakers.
- The power supply with a center tapped transformer and diode rectifier.
- A mechanical system to drive the cassette (the cassette driver).
- The amplifier board.
- The radio board.
Step 2: Study the System.
The system consists of six parts mainly.
- The transformer to step down the high voltage ac into 9 V AC.
- The diode rectifier to convert the AC into 9 V DC.
- Radio board to play music via radio.
- Cassette driver to play music from cassette and to control the cassette. It is a mechanical system.
- The amplifier board to amplify the music nd to give a high power/volume output.
- Stereo speakers.
The cassette driver is the important part of the player. It consist of mechanical switches (for play,pause,fwd,rvs and record),motors and gears to control the rotation of the magnetic cassette,and the tape head (magnetic head).
Magnetic head is the input device for the amplifier board . head reads the cassette and sends the signals to the board.
ie; The amplifier board amplifies signals given by the head.
Mechanisn: Whenever the play key is pressed, the motor rotates the reel of cassette and the head reads the music, sends to the amplifier.
There is a switch associated with the cassette driver mechanism which is connected to the amplifier board. Whenever the play key is pressed this switch is turned on mechanically and tells the amplifier that the cassette is rolling and to start amplifying. This switch is to ensure that the amplifier turns on only when the cassette is rolling and to reduce power consumption. So , the amplifier in on only when the cassette is rolling.
The cassette driver has two connections with the board,
- The input to the amplifier from the head.
Three wires namely ground/common, left and right.
these are the inputs to the amplifier.
2. The switch connection.
two wires connected to the connector on the board named "SW"
Step 3: The Bluetooth Module
The board is taken from a broken bluetooth speaker that works on 5 V DC.
The on/off button is short circuited using a wire piece.
This works on 5 V DC supply and the cassette player has a 9 V DC output, so we need a voltage regulator .
Step 4: The Voltage Regulator.
The 5 V DC voltage regulator is based on LM 7805 regulator IC.
Made the circuit using 7805 and three capacitors on a pcb as per the circuit diagram.
Step 5: Connect Everything Together
Now we have
- Amplifier board.
- bluetooth moddule.
- Power supply and regulator.
We have to connect everything together as per the diagram.
- Connect diode rectifier's output to the voltage regulator's input.
- Connect the voltage regulator output to the bluetooth module.
- Connect the bluetooth module speaker output to the input of amplifier board.
- Short circuit the "SW" pin connection on the board.
Step 6: Boom Box Is Ready......!
The cassette player turned BT boom box is ready.