This circuit is from a 1964 Electronic Design book that presents application ideas for transistors. The circuit uses a transistor from that time, but modern equivalents can be used.
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...