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.
Indicated for applications in the analysis of logic circuits, this circuit was found in 90s Radio...
This circuit is from 1977 documentation, and high current equivalent transistor must be used. The...
Found in an Electronic Design, this circuit makes use of general-purpose bipolar transistors. The circuit...