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

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  • Andy
    ... 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
    Message 1 of 13 , Apr 11, 2013
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      > 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
    • AlienRelics
      ... Here is one: you took a TO-220 transistor off of a heat sink to replace it. You are about to replace it, but you look down at a pile with a bolt, flat
      Message 2 of 13 , Apr 12, 2013
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        --- In Electronics_101@yahoogroups.com, jong kung <jongkung01@...> wrote:
        >
        > John, et al,
        >
        >
        > Thanks...
        >
        > There's so many things they gloss over in EE textbooks. I always see these capacitors, and I KNOW they are suppose to make output signal cleaner - but never understood why or how. They are ALL making sense now.
        >
        > I love these moments of Ah-Ha!!! Decades of wondering all snaps into place in one moment.
        >

        Here is one: you took a TO-220 transistor off of a heat sink to replace it. You are about to replace it, but you look down at a pile with a bolt, flat washer, and split-ring washer... in what order do you reassemble the bolt and washers?

        I found this information about 20 years ago in a machinist's manual, detailing what purpose a split-ring washer is for and why you always use it with a flat washer. It was the opposite of what everyone around me was saying, including experienced EEs and teachers.

        And I recently got into a disagreement with an EE about this very subject.

        Steve Greenfield AE7HD
      • William Myrick
        Steve please share that information,why it is used with, us. Derward Myrick KD5WWI ... From: AlienRelics Sent: Apr 12, 2013 8:02 AM To:
        Message 3 of 13 , Apr 12, 2013
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          Steve please share that information,why it is used with, us.

          Derward Myrick KD5WWI

          -----Original Message-----

          From: AlienRelics

          Sent: Apr 12, 2013 8:02 AM

          To: Electronics_101@yahoogroups.com

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
















          .
        • jong kung
          SG, ... I usually just put thing back in the order I found so I never gave this much thought. But here s my GUESS. (1) Regular washer is often used to SPREAD
          Message 4 of 13 , Apr 12, 2013
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            SG,


            > Here is one: you took a TO-220 transistor off of a heat sink
            > to replace it. You are about to replace it, but you look
            > down at a pile with a bolt, flat washer, and split-ring
            > washer... in what order do you reassemble the bolt and
            > washers?


            I usually just put thing back in the order I found so I never gave this much thought. But here's my GUESS.

            (1) Regular washer is often used to SPREAD the pressure of the bolt or nut (head) to a wider area around the hole.

            (2) The split washer is used to create a slight spring effect to prevent it from coming loose.

            So my guess is to put the split ring washer in between the head of the bolt (or nut) and the regular washer. The regular washer goes up against the hole (pcb, etc.) to spread the pressure evenly - with or without the split washer (the spring).

            =====

            I'm guessing that some people think that the EDGE of the split digs into the surface of the PCB and the head of the bolt (or nut) and the friction is what prevents the fastener from coming loose. But that is not true. It is so that even if the faster is NOT completely tight, there's some pressure that prevents the fastener from just spinning loose.


            Jong
          • 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 5 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 6 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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