Telephone subset arrangement

U.S. Patent Number: 5317634

Abstract: A telephone circuit subset arrangement in which the base/emitter junction of a switching transistor (TR1) coupling an internal battery (B1) to the dialler chip's power terminals (VDD, VSS) is shunted by hook-switch signal contacts (HS) when the subset is brought into the off-hook mode, thereby turning the switching transistor off and disconnecting the battery. The circuit is so arranged that upon the switching transistor turning off, three auxiliary switching transistors (TR3, TR4 and TR5) turn on and operate the subset's line switch to connect line current to the dialler chip's power terminals. A network of resistors (R1, R2 and R3) associated with the switching transistor (TR1) ensure that on the one hand sufficient current is available to turn on the auxiliary switching transistors, and on the other hand limit the current to a magnitude which dose not cause excessive battery discharge while the subset is off-hook.

Inventors: Fox; Ronald C. S. (Randwick, AU)

Assignee: Alcatel N.V. (Amsterdam, NL)

Application Number: 07/691,004

Issued: 1994-05-31

Expired: 2006-05-31

Classes: 379/362 ; 379/387.01; 379/395.01

Field of search: 379/387,362,368,413

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