This configuration can be found in several articles on this site. The one shown in the diagram is from the datasheet of the LM101 series amplifiers, but it can be implemented with other types.
This circuit was obtained in a Hands-On Electronics from the 90's. The circuit turns on one LED at...
This low power circuit for the FM band was found in a spy book from the 90s. The tunnel diode is...
This oscillator is used to modulate video game signals or even small cameras so that they can be...