JPS6480154A - Overcurrent protecting circuit for telephone set - Google Patents

Overcurrent protecting circuit for telephone set

Info

Publication number
JPS6480154A
JPS6480154A JP23680087A JP23680087A JPS6480154A JP S6480154 A JPS6480154 A JP S6480154A JP 23680087 A JP23680087 A JP 23680087A JP 23680087 A JP23680087 A JP 23680087A JP S6480154 A JPS6480154 A JP S6480154A
Authority
JP
Japan
Prior art keywords
resistor
emitter
low resistance
current
current flows
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP23680087A
Other languages
Japanese (ja)
Inventor
Tadashi Murayama
Masanori Tanaka
Shigemitsu Karasutani
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Toshiba Corp
Original Assignee
Toshiba Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Toshiba Corp filed Critical Toshiba Corp
Priority to JP23680087A priority Critical patent/JPS6480154A/en
Publication of JPS6480154A publication Critical patent/JPS6480154A/en
Pending legal-status Critical Current

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  • Devices For Supply Of Signal Current (AREA)

Abstract

PURPOSE:To prevent destruction of a speech controlling transistor(TR) by inserting a low resistance between a speech control TR and a fuse and turning on a shunt TR when a current flowing to the low resistance exceeds a prescribed value. CONSTITUTION:A low resistance R3 of nearly 0.7OMEGA is inserted in series between a positive terminal of a diode bridge and an emitter of a TR 1. When a large current flows through a station power line, a fuse resistor R1 is blown and the current flows to the resistor R3, causing the voltage across the resistor R3 increase. The voltage increases the base current of the TR 3 and when the current exceeds a prescribed value, the TR is turned on and the current flows through the emitter-collector of the TR 3, a resistor R2, the collector- emitter of the TR 2 but does not flow through the TR 1 and a speech circuit 1. Thus, they are protected completely.
JP23680087A 1987-09-21 1987-09-21 Overcurrent protecting circuit for telephone set Pending JPS6480154A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP23680087A JPS6480154A (en) 1987-09-21 1987-09-21 Overcurrent protecting circuit for telephone set

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP23680087A JPS6480154A (en) 1987-09-21 1987-09-21 Overcurrent protecting circuit for telephone set

Publications (1)

Publication Number Publication Date
JPS6480154A true JPS6480154A (en) 1989-03-27

Family

ID=17005976

Family Applications (1)

Application Number Title Priority Date Filing Date
JP23680087A Pending JPS6480154A (en) 1987-09-21 1987-09-21 Overcurrent protecting circuit for telephone set

Country Status (1)

Country Link
JP (1) JPS6480154A (en)

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