Uses TA7668 magnetic head recording and playback dedicated chip design ( disassembly chip, do not take photos if you mind ). Oldfashioned magnetic tape drive, card holder magnetic head amplification dedicated. Dual use for playback and recording. The recording signal input can be connected to the audio output of devices such as computers, mobile phones, MP3 players, etc. for recording. Polishing and power details: AC demagnetization polishing method is used for polishing ( permanent magnet polishing and DC polishing, clean and thorough). The power supply has a rectifier circuit, which can be used for AC input or DC input. Use scenarios Scenario 1: Record from modern devices. Connect the audio output of a computer, mobile phone, or MP3 player to the recording input and capture onto magnetic tape using the dual playback/recording capability. Scenario 2: Play back and preserve old tapes. Use the oldfashioned magnetic tape drive for playback and, if needed, record onto another media to create a preserved copy. Scenario 3: Flexible power operation. Power the unit from AC mains or DC input thanks to the rectifier circuit in the power supply.