Relative impedance meter (CB7487E)

Found in a 1960 Sylvania manual, this circuit can be implemented with a modern equivalent transistor like the BC558.

Instrumentation AC Amplifier (CB12502E)
This circuit increases the sensitivity of a multimeter in the measure of small alternating...
Intrusion Alarm (CB26238E)
This circuit triggers a buzzer or other warning device when the light falling on the sensor is cut...
Pulse Generator (CB883E)
This circuit open and close the relay in intervals adjusted by the potentiometers. The capacitors...