SE9000765L - Telecommunication system for lift and gate - has microphone driving pre-amplifier receiving DC voltage from main amplifier - Google Patents

Telecommunication system for lift and gate - has microphone driving pre-amplifier receiving DC voltage from main amplifier

Info

Publication number
SE9000765L
SE9000765L SE9000765A SE9000765A SE9000765L SE 9000765 L SE9000765 L SE 9000765L SE 9000765 A SE9000765 A SE 9000765A SE 9000765 A SE9000765 A SE 9000765A SE 9000765 L SE9000765 L SE 9000765L
Authority
SE
Sweden
Prior art keywords
amplifier
gate
output
coupled
microphone
Prior art date
Application number
SE9000765A
Other languages
Swedish (sv)
Other versions
SE9000765D0 (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 SE9000765D0 (en) 1990-03-05
SE9000765L true 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
SE9000765D0 (en) 1990-03-05

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Legal Events

Date Code Title Description
NAV Patent application has lapsed

Ref document number: 9000765-9

Effective date: 19921001