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.

Video amplifier (CB8743E)
Found in a 90s Popular Electronics, this circuit is intended for amplifying analog video signals....
Antenna Preamplifier (CB19257E)
This antenna amplifier or booster for receivers from 100 kHz to 30 MHz was published in a...
Proximity Switch (CB24800E)
This somewhat complex circuit was found in the May 1984 issue of Radio Electronics magazine. The...