Telephone amplifier circuit

US4326106A · kind A · utility

Assignees

• Licentia Patent-Verwaltungs-GmbH · DE
• Telefonbau und Normalzeit GmbH

Inventors

• Willy Minner · Schwaigern, DE
• Rainer Rodenheber · Leingarten, DE
• Erhard Reitz · Oberursel, DE

Key dates

• Filing date: Jan 31, 1980
• Grant date: Apr 20, 1982
• Expiry date: Jan 31, 2000

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04M1/60
• WIPO field: Telecommunications
• WIPO sector: Electrical engineering

Abstract

A microphone amplifier in a telephone station furnished with current from the telephone network. When a capacitive degenerative feedback is used in the amplifier a certain time has to pass after applying the supply voltage before the operating point of the amplifier is reached because of the charging time of the capacitor. The switching of the supply voltage occurs at the dialing operation at each digit of a dial number since during the transmission period of a digit the handset including the microphone is switched off the subscriber line which carries the current usd for supplying the amplifier with energy. By the use of a special circuit the charging time of the capacitor is shortened drastically.