SE9000765D0 - DEVICE FOR TELECOMMUNICATIONS, SPECIAL ELEVATORS AND PORTFOLIO FACILITIES - Google Patents

DEVICE FOR TELECOMMUNICATIONS, SPECIAL ELEVATORS AND PORTFOLIO FACILITIES

Info

Publication number
SE9000765D0
SE9000765D0 SE9000765A SE9000765A SE9000765D0 SE 9000765 D0 SE9000765 D0 SE 9000765D0 SE 9000765 A SE9000765 A SE 9000765A SE 9000765 A SE9000765 A SE 9000765A SE 9000765 D0 SE9000765 D0 SE 9000765D0
Authority
SE
Sweden
Prior art keywords
amplifier
output
coupled
appts
microphone
Prior art date
Application number
SE9000765A
Other languages
Swedish (sv)
Other versions
SE9000765L (en
Inventor
P-E Sandlin
Original Assignee
Sandlin & Persson Tele Ab
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 Sandlin & Persson Tele Ab filed Critical Sandlin & Persson Tele Ab
Priority to SE9000765A priority Critical patent/SE9000765L/en
Publication of SE9000765D0 publication Critical patent/SE9000765D0/en
Publication of SE9000765L publication Critical patent/SE9000765L/en

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M11/00—Telephonic communication systems specially adapted for combination with other electrical systems
    • H04M11/02—Telephonic communication systems specially adapted for combination with other electrical systems with bell or annunciator systems
    • H04M11/025—Door telephones

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Alarm Systems (AREA)

Abstract

The appts. is connected via a two-wire circuit to a central unit, which in turn is coupled to a central alarm point or building surveillance room, and receives and answers calls from connected lift-gate telephones. It incorporates a microphone (M) with a pre-amplifier which is fed with DC from a main amplifier. The pre-amplifier emits its speech signal overlaid on its feed voltage and over its output a line-transformer over a capacitor and a resistance is parallel-coupled. - In the pre-amplifier circuit is a light emitting diode which indicates that the microphone is active, and via a two-wire connection a coupling signal is emitted to the operating appts. via the central unit. In this latter unit is a speech exchange relay which shifts between the amplifier input and output, this output being coupled via a transformer to an adjustment resistance.
SE9000765A 1990-03-05 1990-03-05 Telecommunication system for lift and gate - has microphone driving pre-amplifier receiving DC voltage from main amplifier SE9000765L (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
SE9000765A SE9000765L (en) 1990-03-05 1990-03-05 Telecommunication system for lift and gate - has microphone driving pre-amplifier receiving DC voltage from main amplifier

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE9000765A SE9000765L (en) 1990-03-05 1990-03-05 Telecommunication system for lift and gate - has microphone driving pre-amplifier receiving DC voltage from main amplifier

Publications (2)

Publication Number Publication Date
SE9000765D0 true SE9000765D0 (en) 1990-03-05
SE9000765L SE9000765L (en) 1991-09-06

Family

ID=20378759

Family Applications (1)

Application Number Title Priority Date Filing Date
SE9000765A SE9000765L (en) 1990-03-05 1990-03-05 Telecommunication system for lift and gate - has microphone driving pre-amplifier receiving DC voltage from main amplifier

Country Status (1)

Country Link
SE (1) SE9000765L (en)

Also Published As

Publication number Publication date
SE9000765L (en) 1991-09-06

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Legal Events

Date Code Title Description
NAV Patent application has lapsed

Ref document number: 9000765-9

Effective date: 19921001