This circuit uses a Motorola component from the 90's and is suitable for the diode-transistor logic of the time. The circuit can be adapted to use more modern equivalent logic.
Obtained from an English publication, this circuit actually needs a current limiting resistor,...
This 2003 circuit serves to digitally show the intensity of a sound captured by a microphone....
Suggested by a Popular Electronics from the 90s, this circuit uses a buzzer to indicate the...