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.

Delay Circuit (CB10930E)
This circuit was obtained in a 1991 Electronics Handbook. The publication no longer exists, but...
Timed Relay (CB21866E)
We found this circuit in Ferranti's 1974 transistor manual. The components are from the period. Note...
Instrumentation Amplifier (CB12173E)
This instrumentation amplifier was obtained from Popular Electronics in 1993. The operational...