This receiver was found in a 1924 book by Gernsback. The circuit uses three tubes and is powered by 3 batteries of different voltages, common at the time.
This circuit for cars with mechanical ignition systems was found in the Electronics Experimenter handbook...
This code practice circuit was found in a 1990s issue of Radio Amaterur Today magazine. It...
The circuit presented was found in the Linear Applications Handbook of the National Semiconductoir of 1994....