The sensor of this circuit is a photodiode. Equivalent operations can be used, and the instrument can be replaced by the lower current range of a standard multimeter.
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...