US2387269A
(en )
1945-10-23
Telephone system
GB547269A
(en )
1942-08-20
Transmission systems for electrical communication
SE331119B
(oth )
1970-12-14
GB694705A
(en )
1953-07-22
Improvements in or relating to telephone set circuits
GB547304A
(en )
1942-08-21
Electric circuit control
GB902087A
(en )
1962-07-25
Improvements in or relating to electrical bridge networks
GB557710A
(en )
1943-12-01
Circuit arrangements for resistance elements having a high resistance-temperature coefficient
GB835534A
(en )
1960-05-25
Improvements in or relating to symmetrical current circuits fed by direct current
GB1271310A
(en )
1972-04-19
Improvements in or relating to telecommunications system subscriber station circuit arrangements
GB1189377A
(en )
1970-04-22
Improvements in or relating to Telephone Subset Speech Circuits
GB1185514A
(en )
1970-03-25
Improvements in or relating to Telephone Set Circuits.
US4289939A
(en )
1981-09-15
Longitudinal balance arrangements for two-to-four wire telecommunication line circuits
GB542643A
(en )
1942-01-21
Telephone set circuits
GB829307A
(en )
1960-03-02
A negative impedance amplifier with separate input and output particularly for telephone systems
GB805726A
(en )
1958-12-10
Improvements in or relating to circuit arrangements for automatically regulating sidetone damping in telephone stations
GB558761A
(en )
1944-01-19
Circuit arrangements for resistance elements having a high resistance-temperature coefficient
US2167069A
(en )
1939-07-25
Transmission system
GB558632A
(en )
1944-01-13
Improvements in or relating to thermionic valve circuits
GB1004854A
(en )
1965-09-15
Improvements in or relating to loudspeaking telephone apparatus
GB863706A
(en )
1961-03-22
Improvements in or relating to telephone sub-sets
GB994514A
(en )
1965-06-10
Improvements in or relating to bistable electrical circuits
GB868054A
(en )
1961-05-17
Improvements in or relating to telephone sub-sets
JPS56772A
(en )
1981-01-07
Communication current supply circuit
GB372004A
(en )
1932-05-05
Improvements relating to telephone systems
GB862025A
(en )
1961-03-01
Improvements in or relating to subscribers' telephone sets