Null Indicator (CB21930E)

This bridge was found in a Raytheon transistor manual from the 1960s. The transistors are germanium from the time.

250 mW LM386 Amplifier (CB13756E)
The integrated circuit shown in the figure is nothing more than the LM386 sold by Radio Shack,...
Drum synthesizer (CB22204E)
Found in an English publication from the 1980s, this circuit can be built with equivalent...
Pulse Extender (CB19065E)
The transistors of this old circuit from the 60s can be the BC548, in a current version. The...