This circuit was found in a 1977 Radio Handbook. The MOSFET supports an equivalent. Capacitor C must be low leakage.
The circuits shown below consist of diode protections against accidental polarity reversal in the supply...
Found in an Electronics World of 1968 this circuit has a 40 to 12 000 Hz bandwidth providing a 1.9 Vpp...
This circuit was found in an American documentation from 1968. The circuit uses transistors from that...