This filter for receiving audio in telegraphy was found in a magazine 73 for radio amateurs, in an edition of the 80s. The circuit is tuned to 700 Hz and has a 200 Hz bandpass.
This circuit can be powered by 2 or 3 small batteries. The resistor can have values between 220...
These circuits from a May 1994 Electronics Now take advantage of the noise from the junctions of...
This network can be used in a sound project to control the tone. The circuit is from an...