Found in American documentation from the 1980s, this circuit can be designed with equivalent components. The microphone can be of the piezoelectric type.
This circuit was found in a 90s Radio Electronics. It is intended to amplify the sound channel of...
A bridge with greater sensitivity and, therefore, lower consumption for the microcontroller...
Found in a 1964 magazine, this is a small headphone amplifier from 500 ohms to 10 k ohms (magnetic...