The circuit of this product uses 20-30 seconds of single-segment voice recording integrated into the circuit. Its basic circuit includes an oscillator, microphone preamplifier, automatic gain control, a filter circuit, a speaker driver circuit and more. This product utilizes high quality, natural speech restoration technology. Hold down the record button to trigger the speaker, which will beep and start the recording state. The recording time is about 30 seconds. Touch the play button to play the last recording. Through experiments, we have a preliminary understanding of the principles of sound recording, storage, restoration, and other basic circuits and their applications.


Fundamental principles: 

- Voice recording

- Circuits

- Sound recording

- Playback Circuit

- Analog storage

- Audio amplifier

- Restoration