Relative impedance meter (CB7487E)

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

Three-Phase Motors Protection (CB17453E)
This circuit shuts down a three-phase motor in the event of missing one or two phases, thus...
Power Zener (CB216E)
Using in operational amplifier is possible to increase the dissipation power of a zener. This...
20 kHz counter with SCS (CB6614E)
We found this circuit in 1964 General Electric documentation. The circuit works with mechanical...