Found in a 1924 Gernsback publication this circuit uses 4 batteries for power and loop antenna. Listening is over a high-impedance type earphone or loudspeaker common at the time.
This basic configuration can be found in a lot of articles on this site. In this case, the relay...
This circuit was found in a 1997 publication, but it uses few common components and is very...
This circuit prevents the passage of frequencies in a range starting at 1 kHz and can be adjusted...