Tone Oscillator (CB22066E)

Found in old documentation, this oscillator with the LM380 produces an audio tone in a speaker. Frequency is set in VR1.

Alarm with Vibration Sensor (CB16495E)
The sensor of this circuit, from an old documentation, is nothing more than an electret...
Digital Audio Recorder (CB18606E)
This interesting circuit records a few seconds of audio signals, reproducing them in a small...
High Frequency Inverter Follower (CB17160E)
This circuit is based on an operational amplifier that is uncommon today, but that can reach the...