We found this circuit in a Radio Electronics from April 1965. The components are from the time and the power supply is for 12 V cars. The transistor must be equipped with a good heat radiator.
We found this circuit in a technical documentation from the 70's. Any double-gate MOSFET can be...
This interesting passive circuit from an 80's publication measures the distortion of an audio...
The circuit is from 1968, but we can use a modern one like the 741. The symmetrical power supply...