This very high input impedance JFET circuit was found in the 1995 Encyclopedia of Electronic Circuits Volume 5. The JFET is a general-purpose transistor as is the output transistor.
Two operational amplifiers are used in this source obtained in an American documentation...
This class B push-pull amplifier circuit with a few hundred milliwatts of power was found in an...
This circuit is from the Motorola Linear Databook of 1990. The coils must be according to the...