This very complex circuit in terms of the number of transistors was found in Radio Electronics from March 1966. The circuit is for low impedance headphones. The transistors are from the time.
We found this interesting configuration in a 1976 technical documentation. Equivalent diodes can...
Indicated by the Maxim Engineering Journal in the 90's edition, this circuit uses only one...
The gain of this circuit is given by the value of R1 that depends on the current in the...