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.
This circuit shows how to use a 12 V regulator to obtain a higher voltage output. The...
We found this circuit in the 1994 Linear Applications Handbook from National Semiconductor. The...
This circuit was found in documentation from the 1980s. Transistors are general-purpose types like...