JPH04107091A - Call signal detecting circuit - Google Patents

Call signal detecting circuit

Info

Publication number
JPH04107091A
JPH04107091A JP22614990A JP22614990A JPH04107091A JP H04107091 A JPH04107091 A JP H04107091A JP 22614990 A JP22614990 A JP 22614990A JP 22614990 A JP22614990 A JP 22614990A JP H04107091 A JPH04107091 A JP H04107091A
Authority
JP
Japan
Prior art keywords
photocoupler
call signal
voltage
outputting
delay circuit
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
JP22614990A
Other languages
Japanese (ja)
Inventor
Masato Kagawa
Original Assignee
Nec 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 Nec Corp filed Critical Nec Corp
Priority to JP22614990A priority Critical patent/JPH04107091A/en
Publication of JPH04107091A publication Critical patent/JPH04107091A/en
Pending legal-status Critical Current

Links

Abstract

PURPOSE: To prevent an erroneous operation surely by detecting a call signal in the serial circuit of a constant voltage diode, a photocoupler, a resistor and a capacitor, and outputting a detecting signal through a delay circuit.
CONSTITUTION: The forward current of the call signal whose direction changes alternately flowing in a photocoupler 6 is generated by a remaining voltage except for a voltage value specified by a constant voltage diode 5, and a noise voltage and the like causing the erroneous operation are suppressed. An inverse current to the photocoupler 6 flows in a diode 8, not in the photocoupler 6. The call signal detected in the photocoupler 6 can remove the noise whose voltage is high but a duration is short by outputting after the lapse of a specified time in a delay circuit 9. After that, the detecting signal can avoid an influence to the delay circuit 9 from a device in a back position by outputting through a photocoupler 10 as an output signal 11.
COPYRIGHT: (C)1992,JPO&Japio
JP22614990A 1990-08-28 1990-08-28 Call signal detecting circuit Pending JPH04107091A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP22614990A JPH04107091A (en) 1990-08-28 1990-08-28 Call signal detecting circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP22614990A JPH04107091A (en) 1990-08-28 1990-08-28 Call signal detecting circuit

Publications (1)

Publication Number Publication Date
JPH04107091A true JPH04107091A (en) 1992-04-08

Family

ID=16840628

Family Applications (1)

Application Number Title Priority Date Filing Date
JP22614990A Pending JPH04107091A (en) 1990-08-28 1990-08-28 Call signal detecting circuit

Country Status (1)

Country Link
JP (1) JPH04107091A (en)

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