|
GB1078296A
|
|
Improvements in or relating to return speech paging systems
|
|
DE1217823B
|
|
Communication system for buildings
|
|
GB953614A
|
|
Improvements in or relating to electric storage battery charging apparatus and systems using such apparatus
|
|
GB962146A
|
|
Improvements in or relating to communication systems
|
|
GB965186A
|
|
Improvements in or relating to two-way communication telephone systems
|
|
US3189690A
|
|
Two-way telephone systems with talk-listen switching
|
|
US3102169A
|
|
Loudspeaking telephones
|
|
GB874790A
|
|
Improvements in or relating to loudspeaking telephones
|
|
GB922003A
|
|
Improvements in or relating to two-way communication telephone systems
|
|
GB873030A
|
|
Improvements in or relating to intercommunication telephone systems
|
|
US3065300A
|
|
Loudspeaking telephone systems
|
|
US3101453A
|
|
Transistor amplifiers with protective circuit means
|
|
GB853770A
|
|
Improvements in or relating to loudspeaking telephone systems
|
|
GB860547A
|
|
Improvements in or relating to intercommunication telephone systems
|
|
GB821474A
|
|
Improvements in or relating to mechanically interlocked push-button electric switches
|
|
GB853671A
|
|
Improvements in or relating to transistor amplifiers
|
|
GB853672A
|
|
Improvements in or relating to transistor amplifiers
|
|
GB853670A
|
|
Improvements in or relating to electrical circuit assemblies
|
|
DE1006901B
|
|
Dialing device for an automatic telephone system, which consists of a dial switch driven by a motor
|
|
US2764632A
|
|
Intercommunication telephone systems
|
