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.
This circuit was obtained from a 90s Radio Electronics. The integrated circuit used HAA11508 is not...
This article was written by A. Fanzeres in the 1970s. We kept the original text. With the circuit we...
We found this circuit in an English publication in 1991. The circuit can be assembled with...