Adjustable reference (CB21540E)

We found this circuit with 5.3V zener in a Philips publication from the 60s. The op amp could be a modern equivalent.

Field Strength Meter (CB18302E)
This simple field strength meter was found in a 1967 documentation. The transistor is germanium, and the...
Light Controlled Oscillator (CB16728E)
This is yet another version of the light-controlled oscillator that can be found on this website. This...
Transformerless Sensitive Phase Detector (CB8496E)
Found in a 1969 documentation, this circuit for the 20 MHz band does not use a transformer. The circuit is...