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.
This circuit is from the 1983 Intersil Databook. In it we have the use of the ICL7135 as an AD...
This circuit generates a 1 MHz signal for general equipment calibration. The circuit is from an...
We found this circuit in a Motorola publication from the 70s. The circuit can be implemented with...