This old fashioned transistor amplifier was found in a publication of the year 1958. Transformer are the critical components in the circuit and power comes from 6 D cells.
This low power circuit can be powered with voltages from 1.8 V. We find it in a 80s Hands On...
This simple unijunction and bipolar generator appeared in Radio Electronics magazine in September 1865....
This circuit was obtained from an old American documentation having a limited adjustment range....