This circuit was found in an English magazine from 1977. Signal inputs and outputs must be shielded, and the circuit can be powered by battery, since its consumption is low.
This low voltage circuit that generates sine signals was obtained from a Texas Instruments integrated...
We found this source in documentation from the 1980s. The power transistor can be the BD137 and...
This is a factory setting that appears on many commercial devices and at various points on this...