This circuit is from a 1924 book by Gernsback. The receiver uses two tubes and listens to headphones. Power is supplied by battery with the indicated voltages.
We find this circuit in an 80s operational amplifier documentation. The circuit applies to any...
Using a CMOS 4001, this circuit provides frequency readings on an analog instrument. The idea of...
In the figures we have an infrared transmitter with a BC337 switching transistor that must be...