GB895565A - Improvements in or relating to electrical monitoring circuits - Google Patents

Improvements in or relating to electrical monitoring circuits

Info

Publication number
GB895565A
GB895565A GB495559A GB495559A GB895565A GB 895565 A GB895565 A GB 895565A GB 495559 A GB495559 A GB 495559A GB 495559 A GB495559 A GB 495559A GB 895565 A GB895565 A GB 895565A
Authority
GB
United Kingdom
Prior art keywords
transistor
resistor
current
relay
base
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.)
Expired
Application number
GB495559A
Inventor
John Arthur Avery
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.)
British Telecommunications PLC
British Telecommunications Research Ltd
Original Assignee
British Telecommunications PLC
British Telecommunications Research Ltd
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 British Telecommunications PLC, British Telecommunications Research Ltd filed Critical British Telecommunications PLC
Priority to GB495559A priority Critical patent/GB895565A/en
Publication of GB895565A publication Critical patent/GB895565A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
    • H03K17/56—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices
    • H03K17/60—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being bipolar transistors
    • H03K17/64—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being bipolar transistors having inductive loads
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/30—Modifications for providing a predetermined threshold before switching

Landscapes

  • Emergency Protection Circuit Devices (AREA)
  • Protection Of Static Devices (AREA)

Abstract

895,565. Protective arrangements. BRITISH TELECOMMUNICATIONS RESEARCH Ltd. Feb. 11, 1960 [Feb. 12, 1959], No. 4955/59. Class 38 (5). [Also in Group XL (c)] When the current I in a protected circuit goes above or below a predetermined range, it alters the bias on the base of a transistor TR1 to cause it to conduct or to cut-off and so produce the operation or release of a relay RA in the collector circuit of the transistor. In Fig. 2, resistor R6 is normally short-circuited by a transistor TR2 and the current I flowing to earth through a bias resistor R1 produces a potential drop across the resistor R1 in opposition to the potential due to the battery ES with the result that the transistor TR1 is cut-off and the relay is not energized. In the event of the current I falling below the lower limit of the predetermined range, the potential drop across the resistor R1 due to the current I is reduced and the base becomes sufficiently negative for the transistor to conduct. Should the current I exceed the upper limit, then the potential produced by the current across a resistor R4 is sufficient to cause the transistor TR2 to cease conducting and so remove the short-circuit from resistor R6. The base-emitter voltage of transistor TR1 then becomes negative so that transistor TR1 conducts and the relay RA is energized. Fig. 3 (not shown) illustrates a modified arrangement in which the transistor TR1 is normally conducting.
GB495559A 1959-02-12 1959-02-12 Improvements in or relating to electrical monitoring circuits Expired GB895565A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB495559A GB895565A (en) 1959-02-12 1959-02-12 Improvements in or relating to electrical monitoring circuits

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB495559A GB895565A (en) 1959-02-12 1959-02-12 Improvements in or relating to electrical monitoring circuits

Publications (1)

Publication Number Publication Date
GB895565A true GB895565A (en) 1962-05-02

Family

ID=9787039

Family Applications (1)

Application Number Title Priority Date Filing Date
GB495559A Expired GB895565A (en) 1959-02-12 1959-02-12 Improvements in or relating to electrical monitoring circuits

Country Status (1)

Country Link
GB (1) GB895565A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2386078A1 (en) * 1977-04-01 1978-10-27 Yamato Scale Co Ltd Fault indication circuit for seven segment displays - uses current sensing and logic comparator for each segment

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2386078A1 (en) * 1977-04-01 1978-10-27 Yamato Scale Co Ltd Fault indication circuit for seven segment displays - uses current sensing and logic comparator for each segment

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