These circuits were found in Exar documentation from the 90s. The circuits use both a small speaker and a piezoelectric transducer. The integrated circuit is not common today.
We found this circuit in an old American documentation. Transistors can be modern equivalents. ...
In the figure we have the conventional configuration of a differential amplifier with the...
This 8 A high output power amplifier uses two National Instruments LM12s. The maximum capacity of the...