Found in Motorola documentation from the 90's, this circuit has a high input impedance. The power supply must be symmetrical. The circuit can be implemented with modern operational amplifiers.
This circuit is from the LM107 manual, which is a component of the 80s. The circuit can be adapted to...
This small audio amplifier circuit in complementary symmetry was found in the 1974 Mullard...
The coil of this receiver consists of 100 turns of wire 38 to 30 in a ferrite rod and the...