US1192166A
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Differential-microphone repeater.
|
US1137186A
|
|
Telephone-receiver.
|
US1137188A
|
|
Differential-microphone repeater.
|
US1230676A
|
|
Sound-reproducer.
|
US1209397A
|
|
Transmitting apparatus.
|
US1234134A
|
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Loud-speaking telephone system.
|
US1137189A
|
|
Transmitting apparatus.
|
US1175048A
|
|
Transmitter.
|
US1185879A
|
|
Telephone system.
|
US1185878A
|
|
Telephone-amplifier.
|
US1185877A
|
|
Reproducing and transmitting apparatus.
|
CA139438A
|
|
Microphone
|
CA136208A
|
|
Telephone receiver
|
CA136189A
|
|
Telephone repeater
|
US1208296A
|
|
Repeater.
|
US1089534A
|
|
Differential-microphone repeater.
|
US1137187A
|
|
Resonator.
|
US1084070A
|
|
Loud-speaking telephone system.
|
US1079931A
|
|
Microphone.
|
US1033085A
|
|
Differential microphone-transmitter.
|