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.
Found in an old Elektor, this circuit uses two 7-segment displays to indicate the volume of an...
This resistance meter has a linear scale, converting resistances to voltage. The operational...
I got this circuit from an English magazine from 1977. It can still be easily assembled, as the...