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.
This full-wave power control was found in an old American publication. After adaptations and...
This circuit was found in the May 1989 issue of Radio Electronics magazine. The components can be...
The circuit is from old documentation from the 70s, but the components are still common, as the...