This circuit is from a 1969 EEE magazine. The transistors are from that time, but the circuit can be implemented with modern equivalents, such as 2N2646 for Q3.
This amplifier from 100 to 150mW was found in a Japanese documentation from 1967. The circuit uses...
This circuit is from a manual of JFETs and can be implemented with the BF245 and for the bipolar...
This source of some amps for voltages up to 40 V was found in an Italian magazine Elettronica...