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.

Simplified Alarm (CB16418E)
We found this simple alarm circuit in a 1981 documentation. As we can see, it is a car alarm...
Accented Metronome (CB4369E)
We found this circuit in an English magazine from 1976. The magazine no longer exists, but just...
2 W Amplifier (CB6162E)
Suggested by General Electric in a 1968 documentation this integrated amplifier uses a component of...