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.
In the figure we have a simple way to produce tone in a piezoelectric transducer. The frequency depends...
This absolute value amplifier was found in a 90's EDN. Equivalent amplifiers can be used. The...
The integrated circuit used in this configuration for noise reduction on FM radios is not common...