This is a standard cassette suitably modified which plays mp3's in two different ways.
1: Insert into a cassette player and press play.
The unit will only commences playing tracks when the head depresses a switch mounted behind it due to the mechanical action of the player.
2: As a portable stand alone player with integral control panel and additional headphones.
The unit is controlled by an ESP32_C3 in conjunction with a DFplayer Mini and SDcard.
Power is provided by a rechargeable battery with a charger/booster for power management.
Main power switch positions:
1: Off position the unit can be powered directly from the USB_C input.
2: On position and with the USB_C input connected to the unit can be used or left whilst the battery charges.
3: On position and with the USB_C input disconnected power is provided by the battery.
Separation between the modules is maintained by a 3D printed retainer and the switch panel is also 3D printed.
No internal gears are required.