JPS57173212A - Muting circuit - Google Patents

Muting circuit

Info

Publication number
JPS57173212A
JPS57173212A JP56058271A JP5827181A JPS57173212A JP S57173212 A JPS57173212 A JP S57173212A JP 56058271 A JP56058271 A JP 56058271A JP 5827181 A JP5827181 A JP 5827181A JP S57173212 A JPS57173212 A JP S57173212A
Authority
JP
Japan
Prior art keywords
muting
current
trs
terminal
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
JP56058271A
Other languages
Japanese (ja)
Inventor
Hiroto Shibuya
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.)
Panasonic Holdings Corp
Original Assignee
Matsushita Electric Industrial Co 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 Matsushita Electric Industrial Co Ltd filed Critical Matsushita Electric Industrial Co Ltd
Priority to JP56058271A priority Critical patent/JPS57173212A/en
Publication of JPS57173212A publication Critical patent/JPS57173212A/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G3/00—Gain control in amplifiers or frequency changers without distortion of the input signal
    • H03G3/20—Automatic control
    • H03G3/30—Automatic control in amplifiers having semiconductor devices
    • H03G3/34—Muting amplifier when no signal is present or when only weak signals are present, or caused by the presence of noise signals, e.g. squelch systems

Abstract

PURPOSE:To eliminate a shock sound and to obtain the substantially-necessary amount of muting by constituting the variable impedance part of a muting circuit by using the 1st and 2nd circuit parts composed of transistors (TR) of complementary polarities whose emitters are connected directly. CONSTITUTION:An input signal ei from a signal source 24 is transferred as an output signal e0 to an output terminal through a coupling capacitor 23 and a resistance 22. A muting signal is inputted from a terminal 25 to generate a muting control current IM by TRs 12 and 14 and a resistance 16, and thus while a current IM flows through TRs 11 and 18 constituting a current mirror circuit, the current IM flows TRs 19 and 20 forming a current mirror circuit. At this time, a voltage at a terminal 26 rises from an earth point by the base-emitter voltage VBE of a TR13 through the TR13, and drops by the VBE through the TR19 to be held at 0V, so that muting operation generates no switching noise.
JP56058271A 1981-04-16 1981-04-16 Muting circuit Pending JPS57173212A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP56058271A JPS57173212A (en) 1981-04-16 1981-04-16 Muting circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP56058271A JPS57173212A (en) 1981-04-16 1981-04-16 Muting circuit

Publications (1)

Publication Number Publication Date
JPS57173212A true JPS57173212A (en) 1982-10-25

Family

ID=13079510

Family Applications (1)

Application Number Title Priority Date Filing Date
JP56058271A Pending JPS57173212A (en) 1981-04-16 1981-04-16 Muting circuit

Country Status (1)

Country Link
JP (1) JPS57173212A (en)

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5428543A (en) * 1977-08-05 1979-03-03 Toshiba Corp Variable impedance circuit

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5428543A (en) * 1977-08-05 1979-03-03 Toshiba Corp Variable impedance circuit

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