JPS5741014A - Mobile acoustic apparatus - Google Patents

Mobile acoustic apparatus

Info

Publication number
JPS5741014A
JPS5741014A JP11595680A JP11595680A JPS5741014A JP S5741014 A JPS5741014 A JP S5741014A JP 11595680 A JP11595680 A JP 11595680A JP 11595680 A JP11595680 A JP 11595680A JP S5741014 A JPS5741014 A JP S5741014A
Authority
JP
Japan
Prior art keywords
fet81
noise
gain
varied
operated
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
JP11595680A
Other languages
Japanese (ja)
Inventor
Ichiro Hondo
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.)
Hitachi Ltd
Original Assignee
Hitachi 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 Hitachi Ltd filed Critical Hitachi Ltd
Priority to JP11595680A priority Critical patent/JPS5741014A/en
Publication of JPS5741014A publication Critical patent/JPS5741014A/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
    • H03G3/20—Automatic control
    • H03G3/30—Automatic control in amplifiers having semiconductor devices
    • H03G3/32—Automatic control in amplifiers having semiconductor devices the control being dependent upon ambient noise level or sound level

Landscapes

  • Control Of Amplification And Gain Control (AREA)

Abstract

PURPOSE:To constitute a mobile acoustic apparatus so that all users can listen to it in the most desirable state, by constituting in order to be able to set a response level of an automatic sound volume adjusting device corresponding to a surrounding noise, from the outside. CONSTITUTION:An external noise is detected by a microphone, is amplified, and after that, a suitable noise component is taken out by a band-pass filter, and is inputted to a gate terminal 84 of an FET81 of a gain variable amplifier. When gate voltage is varied in accordance with magnitude of a noise, the FET81 is operated as a variable resistor. Since the FET81 is operated as an emitter resistance of a signal amplifying transistor 71, it is capable of changing the gain of the transistor 71 in accordance with a noise. Also, a variation factor of gain by the FET81 is varied by a variable resistor 83 which is connected in series with the FET81.
JP11595680A 1980-08-25 1980-08-25 Mobile acoustic apparatus Pending JPS5741014A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP11595680A JPS5741014A (en) 1980-08-25 1980-08-25 Mobile acoustic apparatus

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP11595680A JPS5741014A (en) 1980-08-25 1980-08-25 Mobile acoustic apparatus

Publications (1)

Publication Number Publication Date
JPS5741014A true JPS5741014A (en) 1982-03-06

Family

ID=14675297

Family Applications (1)

Application Number Title Priority Date Filing Date
JP11595680A Pending JPS5741014A (en) 1980-08-25 1980-08-25 Mobile acoustic apparatus

Country Status (1)

Country Link
JP (1) JPS5741014A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006148541A (en) * 2004-11-19 2006-06-08 Denso Corp Navigation device and program
JP2008216623A (en) * 2007-03-05 2008-09-18 Pioneer Electronic Corp Sound device and speech correcting method

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006148541A (en) * 2004-11-19 2006-06-08 Denso Corp Navigation device and program
JP2008216623A (en) * 2007-03-05 2008-09-18 Pioneer Electronic Corp Sound device and speech correcting method

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