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DE944196C
(de)
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Fernmeldeanlage fuer Fernverkehr
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SE191548C1
(OSRAM)
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US2529166A
(en)
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Automatic switching system applicable to telegraphy
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US3617645A
(en)
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Signaling circuit with audible noise reduction
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US2990457A
(en)
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Tandem echo suppressor circuits
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US1451886A
(en)
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Signaling apparatus for telephone systems
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US1297858A
(en)
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Electromagnetic coil.
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US2052055A
(en)
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Telephone and signal system
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US1997205A
(en)
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Signaling system
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US2362425A
(en)
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Time-measuring equipment
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US1892716A
(en)
|
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Electric train signaling apparatus
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US1614441A
(en)
|
|
Automatic telephone system
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US1850608A
(en)
|
|
Telephone system
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US1665773A
(en)
|
|
Automatic switchboard telephone system
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US1107137A
(en)
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Telephone-exchange system.
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DE740114C
(de)
|
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Einrichtung zur UEberwachung von telegrafischen Verbindungen in Telegrafenvermittlungsanlagen
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US2844660A
(en)
|
|
Circuit arrangement for controlling the operation of key-controlled telephone selection apparatus
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DE658610C
(de)
|
|
Schaltungsanordnung fuer Muenzfernsprecher fuer verschiedenwertige Gespraeche
|
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US2832834A
(en)
|
|
Signalling arrangement for telecommunication systems
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USRE14304E
(en)
|
|
Belay |
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US1957288A
(en)
|
|
Communication system
|
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DE116391C
(OSRAM)
|
|
|
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DE1512946C
(de)
|
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Schaltungsanordnung fur Fernmeldean lagen, insbesondere Fernsprechanlagen mit Induktivwahl
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US1919015A
(en)
|
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Method of determining distances
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US1864381A
(en)
|
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Circuit arrangement for sending of current impulses over telephone lines
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