Multi Tube Amplifier (T446E)

Obtained in MIT documentation this circuit uses several tubes to obtain a large gain in the amplification of small signals.

Transistor Tester (CB1409E )
The indicator instrument of this transistor tester, from an Argentine publication of the 1970s,...
555 Continuity Tester (CB25532E)
This simple 555 component tester was found in the November 1992 issue of Radio Electronics...
Logic Level Tester (CB4469E)
This circuit can use both separate LEDs and a common cathode display when one segment indicates...