Re: small signal NPN transitor for muting microphone


"Frank Bemelman" <f.bemelmanq@xxxxxxxxxxxxxxxxx> wrote in message
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> "RR" <RR@xxxxxx> schreef in bericht
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>> Hello Frank
>>
>> Thank you very much for the reply.
>>
>> The switch is part of the microphone. About five meters away and will
>> pick
>> up some noise. Actually the switch is part of the microphone. Two extra
> wire
>> comes out of the microphone.
>>
>> My apology for no explanation for the diode.
>> I have now uploaded second image to explain why I need diode (Diodes).
>> http://www.psv.co.uk/MicMute2.JPG
>>
>> I hope this new image will do some explanation.
>>
>> My main worry is the diode. I think having this diode in pararal with
>> base-emmiter might reduce ON resistance of the transistor. In any case my
>> another worry is that, will transitor offer low ON resistance at very
>> very
>> low current? Some quick search on transistor database gave me some basic
>> answer about ON resistance, But it only specifed at 3mA.
>>
>> Thank you very much for your help.
>
> Please do not top post, put your replies on the bottom.
>
> Okay, I saw your new schematic. If you are going to mute the output, what
> is the point of muting the input?
>
> --
> Thanks, Frank.
> (remove 'q' and '.invalid' when replying by email)
>
>

Hello Frank,

Thanks again,
Now I know what Top post are! sorry about that.

Original equipment (Bus/Motor coach - Amplifier) had/has voice activated
muting circuit. Which I found totally useless. Was very simple circuit with
2nd half of the op-amp + one transistor + one 330uf capacitor etc. This
voice activated circuit muted input and output. So I have no choice. Also CD
player is connected to power amp. Pre amp also connects to the same point on
the circuit. (simple register job!) If I don't mute pre amp output then
there is noticeable increases in background noise.

Thanks



.

Relevant Pages

  • Re: small signal NPN transitor for muting microphone
    ... Actually the switch is part of the microphone. ... >>> I have now uploaded second image to explain why I need diode. ... > muting circuit. ...
    (sci.electronics.design)
  • Re: small signal NPN transitor for muting microphone
    ... Actually the switch is part of the microphone. ... > I have now uploaded second image to explain why I need diode. ... Thanks, Frank. ...
    (sci.electronics.design)
  • Re: small signal NPN transitor for muting microphone
    ... > I have posted a circuit at this address, ... I can un-mute it by closing the switch. ... > one 4.7K register, one Transistor, one diode and a switch. ... switch in series with the microphone. ...
    (sci.electronics.design)
  • Re: small signal NPN transitor for muting microphone
    ... Actually the switch is part of the microphone. ... I have now uploaded second image to explain why I need diode. ... Some quick search on transistor database gave me some basic ...
    (sci.electronics.design)
  • Re: Interfacing 5V to unknown 10-30V signal
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