Phase shifter (CB21955E)

This circuit for low frequency signals was found in a publication by Gernsback from 1960. The transistor is made of germanium of the time.

JFET variable zener (CB7478E)
We found this circuit in a 1977 Radio Handbook. The JFET can be of any type and the adj can have...
Double-T Oscillator with Diode Regulator (CB25913E)
This double-T sine wave oscillator was found in the December 1995 issue of Electronics Now...
Limit Alarm (CB5075E)
This limit alarm was found in a 1980s US documentation. Comparators can be equivalent and the...