Microphone

Briefintroduction

Themicrophoneisoneoftheimportantpartsofthetelephone.Itcanconvertsoundintovoicecurrent,soitisanacoustic-electricconversiondevice.Microphonesaregenerallydividedintotwocategories,namelylinearmicrophonesandnon-linearmicrophones.Peoplecallamicrophonewhosesensitivitydoesnotchangewiththesoundpressureasalinearmicrophone,andviceversa,itiscalledanon-linearmicrophone.Amongthecommonlyusedmicrophones,carbonmicrophonesarenon-linearmicrophones,electromagneticmicrophones,movingcoilmicrophones,piezoelectricmicrophones,andelectretmicrophonesarelinearmicrophones.Device.

Themicrophoneisdividedintopositiveandnegativepoles.Pleasepayattentiontoitduringmaintenance.Ifthepolarityisreversed,themicrophonewillnotbeabletooutputsignals.Inaddition,themicrophoneneedstoprovideabiasvoltageforitwhenitisworking,otherwise,therewillbeafailurephenomenonthatcannotsendthephone.

Theconnectionbetweenthemicrophoneandthemotherboardisatouchtypeandaweldingtype.

Point-touchmobilephonesfailtosendcallsbecauseofpoorcontactcontact.Youcancleanthecontactsfirstandtightenthehousingscrews;forweldedmobilephones,thetransmitterisweldedtothemainboard.Therewillbenopoorcontact.Thefailuretosendacallismostlyduetothemicrophoneenteringthedustandblockingthesendingholeorthemicrophoneitselfisdamaged.Ofcourse,theaudiocircuitdamageisnotruledout.

Themicrophonehaspositiveandnegativepolarity.Ifthepolarityisreversed,themicrophonecannotoutputsignals.Themethodtojudgewhetherthemicrophoneisdamagedis:putthedigitalmultimeterintheR×1Ωposition,thepositivepoleoftheredtestpenandthenegativepoleofthemicrophone(theoppositeisthecasefortheanalogmultimeter),andspeaktothemicrophoneIfthemicrophoneisgood,thereadingofthemultimeterwillchangeorthepointerwillswing.

Performanceindicators

1.Sensitivity:Itreflectstheefficiencyofsound-to-electricconversionofthemicrophone.Thetransmissionsensitivityincludessoundpressuresensitivityandsoundfieldsensitivity.Thesoundpressuresensitivityreferstotheoutputvoltageofthemicrophonewhenthesoundpressureonthediaphragmofthemicrophoneis1Pa.

2.Frequencyresponse:Sincethesensitivityisrelatedtothefrequencyofthesound,whenthefrequencychanges,thesensitivityalsochanges.Therefore,thefrequencyresponseofageneralmicrophoneisacurve.

Commontypes

1.Charcoalmicrophone

Charcoalmicrophone,alsoknownascarbonparticlemicrophone.Accordingtothesizeoftheselectedcarbonparticles,thecarbonmicrophonecanbedividedintothreetypes:lowresistance,mediumresistance,andhighresistance.Theresistanceofthelow-resistancecarbonmicrophoneis30-65Ω,theresistanceofthehigh-resistancecarbonmicrophoneis150-300Ω,andtheresistanceofthemedium-resistancecarbonmicrophoneissomewhereinbetween.Low-resistancecarbonparticletransmittersaremainlyusedformagnettelephones,medium-resistancecarbonparticletransmittersaremainlyusedforcommon-typetelephonesandshort-distanceautomatictelephones,andhigh-resistancecarbonparticletransmittersaremainlyusedforlong-distanceautomatictelephones.Telephone.

Theadvantagesofthecarbonparticlemicrophonearelargeoutputpower,highsensitivity,simplestructure,andlowcost;thedisadvantageisthatthecarbonparticlesarepronetomoisture,adhesion,andaging,sothebasicworkisunstable,thesoundqualityispoor,andthenoiseislarge..

2.Electretmicrophone

Theelectretmicrophoneisalsocalledelectretcondensermicrophone,whichisnamedaftertheelectretsheet.Theelectretmicrophoneconnectsthefieldeffecttubeandtheacoustic-electricconversiondeviceasnecessary,andisencapsulatedinacircularaluminumshell.Itsleadwirehastwoforms:two-wireandtwo-wire.

Duringtransmission,thedielectricbodyintheelectretmicrophoneisvibratedbysoundwavestogenerateaweakcurrent,andthenthroughtheimpedanceofthefieldeffecttubecircuit,thevoicecurrentisoutput.Theelectretmicrophonehaslowsensitivityandlowoutputpower,soanamplifiercircuitmustbeaddedwhenusingit;atthesametime,becauseofthefieldeffecttube,1.5-12VDCvoltagemustbeadded.

Sincetheelectretmicrophonehassimplestructure,smallsize,lightweight,widefrequencyresponse,goodfidelity,andlowprice,itisnowwidelyusedinvarioustelephones.