Found in American documentation from the 90s, this circuit makes use of common components. The load must be according to the supply voltage.
This excellent 3-transistors audio preamplifier is suitable for use with low impedance...
IDT ZSSC3230 Capacitive Sensor Signal Conditioner Available from Mouser Electronics stock, this IDT...
No information is given about the transformers in this circuit suggested by Motorola in a 1968...