Remote control tester (CB7823E)

This circuit from a 90s Electronics Now, uses a 4010 gate as a signal amplifier. The circuit triggers an indicator LED.

Broadband IR Receiver TDA3047 (CB15396E)
This receiver for infrared remote control was found in the Philips Databook of 1990, The circuit...
Flood alarm (CB20728E)
Found in an English publication from the 1980s, this circuit uses components that are still common...
Crystal tuned amplifier (CB7453E)
This circuit was found in Maxim's documentation from the 90's. The frequency of the circuit is...