Signal Tracer and Capacitor Tester (T1241E)

This mains powered two-in-one instrument was found in a Radio Craft from March 1948. The headphone must be high impedance.

Audio Oscillator (CB10844E)
This circuit was obtained in a 1979 101 Electronics Projects. The circuit can be assembled easily,...
Hysteresis compensator (CB7980E)
Suggested by a 90's Linear Databook, this circuit compensates for capacitor hysteresis. The main...
Analog Isolator (CB13571E)
This circuit serves to isolate analog signals, for example, audio signals in a secure link...