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Morgan Jones. "Valve Amplifiers" excerpt: Clarification requested

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  • Morgan Jones. "Valve Amplifiers" excerpt: Clarification requested

    re: Conventional Current Flow and Electron Flow (Page 41)

    Can someone please explain exactly what this means and what the implications are in musical electronics.
    As I read it, it seems to imply that current and electron flow as conventionally understood is ass-backwards or wrong due to an historical error.
    What am I missing?
    Thanks
    SG

    Note: The information I'm referring to is on Page 41
    You must scroll down to access it.

    https://books.google.com/books?id=Qd...page&q&f=false
    Last edited by sgelectric; 08-19-2020, 02:17 AM.

  • #2
    Page 41 says not available on this preview.

    Nothing is "wrong", it is just two ways of looking at something. Older stuff tended to think in terms of "conventional current". That is the reverse of "electron flow". HAving looked at it all for decades , it is obvious that electron flow describes the physical world better. We all know electrons flow from cathode to plate for example. But in amplifier electronics we really are not looking at the physical world. Yes, we can see resistors and tubes, but all the electricity is invisible, and all the circuits are abstracts - representations of the inner works. So in my head, I use conventional current. I know the real world is reverse, but so what. I can read a Jules Verne book in English, even though it was really written in French.

    Conventional current has the advantage that the arrows on diodes and transistors point the right way - and of course backwards for electrons. We use positive power supplies mostly in tube amps, and to me it is way easier to think in terms of the B+ supply sending out current all finding its way to ground. I find that easier thinking than that the ground is a great seething pool of excess electrons all trying to find their way up to various points of positive where they are aching for electrons. Yes, even though that is what is happening.

    What matters is you have a consistent view. And as long as you understand how a tube functions, I think in the overall picture, it doesn't much matter which way you think the electrons flow in the circuits. SO don't obsess over it. I have say a -100v power supply, and I need -50v for bias in my circuit. I know I need a voltage divider between -100v and ground to create my -50v, and who cares which way the electrons go to make it?

    Of course it can be an intersting and loud discussion at the academic level, and if that is your thing, then carry on. But if you want to learn amp repair and building, then it is just that, academic. But the load lines crowd will probably disagree with me. This is one of those topics that comes up all the time and quickly turns into the same old arguments. Tube amp versus solid state, electron flow versus conventional current, toilet paper roll end out front or against the wall.
    Education is what you're left with after you have forgotten what you have learned.

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    • #3
      Enzo,
      Thank you for clarifying this for me.
      i have no desire to engage in any on-going academic discussion regarding this topic.
      It's just something I encountered a long time ago and have never come to understand.
      Regards, SG

      Sorry that Page 41 didn't come up on your preview. It did on mine and continues to do so.
      Perhaps it is a result of Google Books algorithms and "fair use" copyright restrictions.
      Don't really know.

      Thanks again.

      Comment


      • #4
        Click image for larger version

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        • #5
          It doesn't really matter which way current flows, as long as you can keep the signs straight. When people talk about an electron cloud, I think about the Three Stooges when Moe says "Spread Out". Electrons floating around in a cloud would repel each other.
          WARNING! Musical Instrument amplifiers contain lethal voltages and can retain them even when unplugged. Refer service to qualified personnel.
          REMEMBER: Everybody knows that smokin' ain't allowed in school !

          Comment


          • #6
            Originally posted by loudthud View Post
            . Electrons floating around in a cloud would repel each other.
            Not sure what you mean to say.
            Of course the electrons in the cloud around the hot cathode do repel each other. But the attracting force between the cathode and the electrons (called "mirror force") is consideraly stronger. So all electrons eventually fall back onto the cathode - if there is no even stronger force that accelerates them towards the plate. The latter is provided by the plate (screen) voltage.

            - Own Opinions Only -

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            • #7
              Just to add the picture, there is positive current and there is negative current. The latter is the opposite of the former. In the absence of other potentials, both types of current seek out pathways to 'neutralisation' (at whatever potential is the neutral reference point). You see this in action in the opposite halves of a push-pull output transformer's primary winding when the amplifier is in Class A mode: when current in one half is positive, the current in the other half is negative. (Of course in an OT, the current on each side is going through its half of the primary winding in the opposite turns-direction to the reverse current which is occurring in the other half of the primary winding, so that the cumulative effect is that the magnetising current in the core is twice what it otherwise would be if only one-half of the OT primary was conducting)
              Building a better world (one tube amp at a time)

              "I have never had to invoke a formula to fight oscillation in a guitar amp."- Enzo

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              • #8
                It gets tougher in solid state devices, where it is the 'lack' of an electron (called a 'hole') that effectively transfers current through material.

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                • #9
                  Frankly, in my head, unless someone really finds the physics of transistors fascinating, I don't sweat the holes. I liken that to cooking spaghetti sauce by considering all the chemical reactions underway in the pot. I season it with some salt, never really considering that salt is sodium and chlorine looking to react with other elements in the food. Tomatoite? Onium? Macaronium?


                  (And for anyone actually interested in the chemistry in our lives, I highly recommend any - or all - of Dr.Joe Schwarcz' books)
                  Education is what you're left with after you have forgotten what you have learned.

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                  • #10
                    Originally posted by Enzo View Post
                    Frankly, in my head, unless someone really finds the physics of transistors fascinating, I don't sweat the holes.
                    Quote of the day!

                    Building a better world (one tube amp at a time)

                    "I have never had to invoke a formula to fight oscillation in a guitar amp."- Enzo

                    Comment


                    • #11
                      Originally posted by sgelectric View Post
                      As I read it, it seems to imply that current and electron flow as conventionally understood is ass-backwards or wrong due to an historical error.
                      What am I missing?
                      As tubeswell noted, you are missing that there is positive current and negative current. If you try to reckon current in the same direction as electrons, then you get into a difficult situation where electrons are carrying NEGATIVE charge in the direction of POSITIVE current. That is even more ass-backwards than the conventional way!

                      https://books.google.co.uk/books?id=...page&q&f=false

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                      • #12
                        I've often read about 50/50 chance and the decision regarding current flow being a guess/random/arbitrary, but I don't hold with that because decisions were made at the time based on observation and the prevailing science. It seems unlikely that the decision on direction of flow was purely a coin flip and more likely based upon experiment, possibly evolving from observation of the effects of charged bodies and static electricity. I wonder how many scientific 'facts' we hold to be true right now will be overturned in the future based upon new discoveries?

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