GB892198A - Electrical protection system - Google Patents

Electrical protection system

Info

Publication number
GB892198A
GB892198A GB1996760A GB1996760A GB892198A GB 892198 A GB892198 A GB 892198A GB 1996760 A GB1996760 A GB 1996760A GB 1996760 A GB1996760 A GB 1996760A GB 892198 A GB892198 A GB 892198A
Authority
GB
United Kingdom
Prior art keywords
central station
contacts
line
signal
substation
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
GB1996760A
Inventor
Manfred Wolfgang Muehter
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.)
American District Telegraph Co
Original Assignee
American District Telegraph Co
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 American District Telegraph Co filed Critical American District Telegraph Co
Priority to GB1996760A priority Critical patent/GB892198A/en
Publication of GB892198A publication Critical patent/GB892198A/en
Expired legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B13/00—Burglar, theft or intruder alarms
    • G08B13/22—Electrical actuation
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B29/00—Checking or monitoring of signalling or alarm systems; Prevention or correction of operating errors, e.g. preventing unauthorised operation
    • G08B29/02—Monitoring continuously signalling or alarm systems
    • G08B29/06—Monitoring of the line circuits, e.g. signalling of line faults
    • G08B29/08—Signalling of tampering with the line circuit

Abstract

892,198. Electric alarm systems. AMERICAN DISTRICT TELEGRAPH CO. June 7, 1960, No. 19967/60. Class 118. In an alarm system in which a direct current of predetermined value normally flows in a transmission line connecting a substation to a central station and changes in the value of this current are detected at the central station, an oscillator is provided at the substation which transmits an A.C. signal of predetermined amplitude over the line to the central station where an increase or a decrease in the value of the A.C. is detected. The invention is described as applied to a burglar alarm system. The D.C. arrangements are conventional and the change from night to day protection is effected by opening contacts 27, 70 and 75 and closing contacts 83, 84 and 85 so that the protection devices 71, 73, 79 and 80 and the door contacts 72 are rendered inoperative. In the night condition, breaks and grounds operate the central station drop 15 in the usual manner to actuate the alarm circuits 16. In order to detect attempts to tamper with the system by bridging the line 11, 12 with a resistance approximating to that of the protection circuits, a Colpitts oscillator 17 including a transistor 21 is provided at the substation and continuously transmits over the line 11, 12 an A.C. signal which is amplified by the push-pull transistor amplifier 40 at the central station, rectified and applied to " high " and " low " relays RH and RL, the gain of amplifier 40 being adjusted by means of taps 50, 51 so that RL is normally energized and RH de-energized. If, due to tampering, the A.C. signal amplitude falls, RL falls away and the closure of contacts RL1 lights lamp 63, energizes the auxiliary winding RHX of relay RH to bring up RH which locks, and operates RA to sound the buzzer BZ. The central station operator then operates switches 61 and 64. The buzzer is thus silenced, RHX and RA are de-energized and lamp 63 is connected directly across the D.C. supply. If the tampering produces an increase in the A.C. signal, RH will pull up with similar results. Testing.-The operator opens switch 89 and closes switch 90 to connect reverse battery to the line 11, 12. This normally energizes the bell coil BC and its contacts BC1 interrupt the circuit, the ringing of the bell indicating to the subscriber that the system is in working order. In addition the current induced in the secondary winding of transformer 95 lights the neon lamp 98.
GB1996760A 1960-06-07 1960-06-07 Electrical protection system Expired GB892198A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB1996760A GB892198A (en) 1960-06-07 1960-06-07 Electrical protection system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1996760A GB892198A (en) 1960-06-07 1960-06-07 Electrical protection system

Publications (1)

Publication Number Publication Date
GB892198A true GB892198A (en) 1962-03-21

Family

ID=10138099

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1996760A Expired GB892198A (en) 1960-06-07 1960-06-07 Electrical protection system

Country Status (1)

Country Link
GB (1) GB892198A (en)

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8330606B2 (en) 2010-04-12 2012-12-11 Verifone, Inc. Secure data entry device
US8358218B2 (en) 2010-03-02 2013-01-22 Verifone, Inc. Point of sale terminal having enhanced security
US8405506B2 (en) 2010-08-02 2013-03-26 Verifone, Inc. Secure data entry device
US8432300B2 (en) 2009-03-26 2013-04-30 Hypercom Corporation Keypad membrane security
US8593824B2 (en) 2010-10-27 2013-11-26 Verifone, Inc. Tamper secure circuitry especially for point of sale terminal
US8595514B2 (en) 2008-01-22 2013-11-26 Verifone, Inc. Secure point of sale terminal
US8884757B2 (en) 2011-07-11 2014-11-11 Verifone, Inc. Anti-tampering protection assembly
US8954750B2 (en) 2011-01-06 2015-02-10 Verifone, Inc. Secure PIN entry device
US9013336B2 (en) 2008-01-22 2015-04-21 Verifone, Inc. Secured keypad devices
US9213869B2 (en) 2013-10-04 2015-12-15 Verifone, Inc. Magnetic stripe reading device
US9595174B2 (en) 2015-04-21 2017-03-14 Verifone, Inc. Point of sale terminal having enhanced security
US9691066B2 (en) 2012-07-03 2017-06-27 Verifone, Inc. Location-based payment system and method
US9777510B2 (en) 2011-03-03 2017-10-03 Assa Abloy Ab Tamper switch activation without power
US10544923B1 (en) 2018-11-06 2020-01-28 Verifone, Inc. Devices and methods for optical-based tamper detection using variable light characteristics
US11397835B2 (en) 2014-07-23 2022-07-26 Verifone, Inc. Data device including OFN functionality

Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9032222B2 (en) 2008-01-22 2015-05-12 Verifone, Inc. Secure point of sale terminal
US9779270B2 (en) 2008-01-22 2017-10-03 Verifone, Inc. Secured keypad devices
US9436293B2 (en) 2008-01-22 2016-09-06 Verifone, Inc. Secured keypad devices
US8595514B2 (en) 2008-01-22 2013-11-26 Verifone, Inc. Secure point of sale terminal
US9250709B2 (en) 2008-01-22 2016-02-02 Verifone, Inc. Secure point of sale terminal
US9013336B2 (en) 2008-01-22 2015-04-21 Verifone, Inc. Secured keypad devices
US8432300B2 (en) 2009-03-26 2013-04-30 Hypercom Corporation Keypad membrane security
US8358218B2 (en) 2010-03-02 2013-01-22 Verifone, Inc. Point of sale terminal having enhanced security
US8760292B2 (en) 2010-03-02 2014-06-24 Verifone, Inc. Point of sale terminal having enhanced security
US9275528B2 (en) 2010-03-02 2016-03-01 Verifone, Inc. Point of sale terminal having enhanced security
US8988233B2 (en) 2010-03-02 2015-03-24 Verifone, Inc. Point of sale terminal having enhanced security
US8330606B2 (en) 2010-04-12 2012-12-11 Verifone, Inc. Secure data entry device
US8710987B2 (en) 2010-08-02 2014-04-29 Verifone, Inc. Secure data entry device
US8405506B2 (en) 2010-08-02 2013-03-26 Verifone, Inc. Secure data entry device
US8593824B2 (en) 2010-10-27 2013-11-26 Verifone, Inc. Tamper secure circuitry especially for point of sale terminal
US8954750B2 (en) 2011-01-06 2015-02-10 Verifone, Inc. Secure PIN entry device
US9792803B2 (en) 2011-01-06 2017-10-17 Verifone, Inc. Secure PIN entry device
US9777510B2 (en) 2011-03-03 2017-10-03 Assa Abloy Ab Tamper switch activation without power
US8884757B2 (en) 2011-07-11 2014-11-11 Verifone, Inc. Anti-tampering protection assembly
US9390601B2 (en) 2011-07-11 2016-07-12 Verifone, Inc. Anti-tampering protection assembly
US9691066B2 (en) 2012-07-03 2017-06-27 Verifone, Inc. Location-based payment system and method
US9213869B2 (en) 2013-10-04 2015-12-15 Verifone, Inc. Magnetic stripe reading device
US11397835B2 (en) 2014-07-23 2022-07-26 Verifone, Inc. Data device including OFN functionality
US9595174B2 (en) 2015-04-21 2017-03-14 Verifone, Inc. Point of sale terminal having enhanced security
US10544923B1 (en) 2018-11-06 2020-01-28 Verifone, Inc. Devices and methods for optical-based tamper detection using variable light characteristics

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