This primitive solar radio was found in a Gernsback publication from 1960. The transistor is made of germanium of the time and the earphone is magnetic with high impedance.
It is an interesting toy containing several potentiometers and switches, allowing children to...
This NEC commercial amplifier was manufactured in Japan in the 1960s. The circuit uses 4...
In the figure we have an application of a voltage comparator in a circuit that fires with the...