High impedance stage (CB20564E)

This high input impedance amplifier stage was found in a 1963 documentation. The transistor germanium of the time.

Regulator with the SG1524 (CB5454E)
The component used in this regulator is not common today. The switching circuit is from an 80's...
Analog frequency meter (CB23566E)
This analog frequency meter for low frequencies was found in Radio Electronics magazine from July...
1 Hz sinusoidal oscillator (CB8045E)
This circuit was obtained in a 1970 EEE and applies to almost any operational amplifier. The...