Door buzzer or alarm (CB20492E)

This solar powered circuit was found in a 1991 documentation. The transistor is a general purpose NPN.

Digital capacitance control (CB7552E)
This circuit is a digitally controlled variable capacitor. We found it in American documentation from...
Developing Table For Silk Screen (CB4445E)
This is an old 1988 circuit consisting of a timer or time control for exposing silk-screen arrays. The...
Thermocouple amplifier (CB9844E)
Found in documentation from the 90's, this circuit can be implemented based on modern operational...