This old 1967 audio preamp uses germanium transistors. It was found in Japanese documentation at the time and has a gain of 70 dB, being powered by p V. The input sensitivity is only 12 mV.
This circuit is from an American documentation from 1975. The single junction transistors can be...
This circuit is of an old Argentine magazine of the 70's. The difficulty for its assembly is in...
This small control for DC motors up to approximately 1 A uses an operational amplifier that admits...