Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Telefonica SA
Original Assignee
Telefonica Nacional de Espana SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Telefonica Nacional de Espana SAfiledCriticalTelefonica Nacional de Espana SA
Priority to ES0435617ApriorityCriticalpatent/ES435617A1/en
Publication of ES435617A1publicationCriticalpatent/ES435617A1/en
"ADVANCED CIRCUIT FOR TELEPHONE APPARATUS" characterized in that it consists of dynamic microphone and receiver, automatic regulator of gain of the transmitting system, automatic regulator amplifier of the sensitivity of the receiver, automatic regulator of the interface equilibrium network and coupling interface. (Machine-translation by Google Translate, not legally binding)
ES0435617A1975-03-141975-03-14Advanced circuit for telephone appliance. (Machine-translation by Google Translate, not legally binding)
ExpiredES435617A1
(en)
A device for maintaining secret conversations between at least two people located at a little distance from another one. (Machine-translation by Google Translate, not legally binding)
Apparatus for reception and transmission of acoustic signals applicable to a telephone set (Machine-translation by Google Translate, not legally binding)