This circuit that imitates the sound of the cowboys' calls with their “louder” was found in a Hands On Electronics from the 80's. The integrated circuits used are from that time.
This receiver for infrared remote control was found in the Philips Databook of 1990, The circuit...
Found in an English publication from the 1980s, this circuit uses components that are still common...
This circuit was found in Maxim's documentation from the 90's. The frequency of the circuit is...