Following the American FCC rules, this 90s Radio Electronics circuit shows how to use a transformer to isolate the telephone line from an amplifier circuit.
Found in a 70s documentation, this amplifier employs an uncommon operating system today. The power...
This circuit is from a 1964 publication. The circuit takes advantage of the component's resistance...
The figure circuit retains in the capacitor load, the value of the input voltage, keeping it...