The circuit selected is from the 1960 Mullard transistor reference manual. The circuit is powered by a single 1.3 V battery and the transistors are germanium.
We found this commercial circuit sold as PT-40 in Japan in the 1960s in a documentation of the...
This small audio amplifier is based on the LM390 with a minimum of external components. We found it...
This circuit is from a 1950 documentation, being one of the first to use the then discovered...