This circuit is for old telephones with analog lines. It was found in the May 1988 Radio Electronics magazine. The circuit is powered by the line signal voltaje.
This circuit can be powered by 2 or 3 small batteries. The resistor can have values between 220...
More and more supercapacitors are being used as supplementary sources of energy in several...
This circuit for ceramic cartridges was found in the March 1993 issue of Electronics Now magazine. Q1...