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Re: [Electronics_101] what does this capacitor do (Alan) ?

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  • John Popelish
    You might think that more capacitance is simply better, because it increases the low pass filter attenuation for any noise. But this must be weighed against
    Message 1 of 13 , Apr 12, 2013
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      You might think that more capacitance is simply better, because it
      increases the low pass filter attenuation for any noise. But this must be
      weighed against the time it takes for the bias point to stabilize, after
      power is turned on, of the effect of having that charged capacitor dumping
      charge into the input pin, after the power supply has been turned off.
      Sometimes the resistor to the far rail in the bias divider needs to be
      paralleled with a reverse biased diode, to drain that capacitor charge back
      to the rail, as the supply voltage falls, to prevent damage to a sensitive
      input.


      On Fri, Apr 12, 2013 at 12:58 AM, Andy <ai.egrps@...> wrote:

      > > Is there an approx / general rule on at what amplification and freq the
      > noise might be important?
      >
      > I rather doubt it. What's unimportant in one usage, may be critical in
      > another.
      >
      > What freq. range is pretty obvious though. If it is within the
      > frequency range of your circuits, and/or your signals, then it is
      > worth considering.
      >
      > Andy
      >
      >
      > ------------------------------------
      >
      > Please trim excess when replyingYahoo! Groups Links
      >
      >
      >
      >


      [Non-text portions of this message have been removed]
    • Willie Pierce
      It depends I ve seen lock washers used to slightly cut into or gouge a little on a metal surface to make sure it has a clean contact point.... but in general
      Message 2 of 13 , Apr 12, 2013
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        It depends I've seen lock washers used to slightly cut into or gouge a little on a metal surface to make sure it has a clean contact point....

        but in general I've always been told it was use to keep pressure on the bolt so it stayed tight.

        On Apr 12, 2013, at 10:57 AM, John Popelish <jpopelish@...> wrote:

        > You might think that more capacitance is simply better, because it
        > increases the low pass filter attenuation for any noise. But this must be
        > weighed against the time it takes for the bias point to stabilize, after
        > power is turned on, of the effect of having that charged capacitor dumping
        > charge into the input pin, after the power supply has been turned off.
        > Sometimes the resistor to the far rail in the bias divider needs to be
        > paralleled with a reverse biased diode, to drain that capacitor charge back
        > to the rail, as the supply voltage falls, to prevent damage to a sensitive
        > input.
        >
        > On Fri, Apr 12, 2013 at 12:58 AM, Andy <ai.egrps@...> wrote:
        >
        > > > Is there an approx / general rule on at what amplification and freq the
        > > noise might be important?
        > >
        > > I rather doubt it. What's unimportant in one usage, may be critical in
        > > another.
        > >
        > > What freq. range is pretty obvious though. If it is within the
        > > frequency range of your circuits, and/or your signals, then it is
        > > worth considering.
        > >
        > > Andy
        > >
        > >
        > > ------------------------------------
        > >
        > > Please trim excess when replyingYahoo! Groups Links
        > >
        > >
        > >
        > >
        >
        > [Non-text portions of this message have been removed]
        >
        >


        [Non-text portions of this message have been removed]
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