This NEC commercial amplifier was manufactured in Japan in the 1960s. The circuit uses 4 transistors from the time and was powered by a 9 V battery voltage formed by large batteries.
The circuit in the figure uses the four current amplifiers of the LM3900 to generate a sawtooth signal...
This circuit was found in an old Motorola documentation from the 70s, as it uses one of its...
This circuit for an optical audio link using LED or LASER was found in a 90s QST magazine. The circuit...