This circuit was obtained from a 1947 amplifier manual. The circuit makes use of a transformer source, but it can also be battery powered.
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...