This circuit is from Delco Radio found in a 1968’s documentation. The transistors are of the time and are not given information about the driver transformer. Note the high supply voltage.
This circuit was found in Motorola documentation from the 1980s. PUTs are not common components...
This low distortion circuit was found in a 1964 Electronic Design. The transistor admits...
This circuit is based on an uncommon Texas component today, as found in an American 1980s...