This LM380-based circuit was found in documentation from the 1980s. The components are current, and the transistor may be a general-purpose equivalent. Note the use of a medium impedance speaker.
Found in a publication from the 60's, this circuit uses the CK722, germanium transistor of the...
This circuit produces the sound of a motorcycle or an outboard motor. The frequency is adjusted in the...
This circuit was found in Popular Electronics from February 1967. Transistors are from the period....