This circuit provides a reference voltage of 2.5 V adjusted in the trimpot. The transistor can be the BC558 (in the drawing it came out as NPN). The control is done by a rectangular input signal.
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...