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+ and _ not so?

Discussion in 'General Technical Questions and Answers' started by KC9IUX, May 20, 2008.

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  1. KB0TT

    KB0TT Premium Subscriber QRZ Page

    KØRGR:

    Clever concept indeed !

    This theory is basic Chemistry 1Ø1 ( use the periodic table for available electron transfer or bonding) . Physics 101 also fits the bill.


    JB
     
  2. AB8RU

    AB8RU Ham Member QRZ Page

    But get the color of your wire mixed up

    I had more people who wired their radios backwards and whats going on when they did the household wiring totally different, after a quote of $40.00 to fix this guys 11 meter rig I wound up owning it, and I have fixed 2 of those in my time even sold one and I think someone has the other one I think, something like that.

    Its fun when you learn to troubleshoot. :p
     
  3. VK6ZGO

    VK6ZGO Ham Member QRZ Page

    What Eric kl7aj said!!

    Because Electrical Engineering Pre-dated Electronics,the Degree level courses all used Conventional Current flow (or "pretend current" as I call it!).

    In VK,most Technical School type courses used Electron Flow,but we were told that the various Rules( Corkscrew rule,etc). were based on Conventional Current flow.

    Try to analyse the operation of a vacuum tube using Conventional Current flow!

    73,VK6ZGO
     
  4. K2XC

    K2XC Guest

    Hole flow

    Hole flow was designed to teach digital solid state electronics. They had to have a way to teach how the new solid state diodes and transistors worked that replaced the old tubes. Its a chemical process (magic) that goes on inside the device. All I need is the pin-out instructions to make the correct connections. We use to have alot of fun in the digital lab classes shooting leds at each other by connecting the LED leads backwards (-) on (+) and (+) on (-) apply power and the top of the led snaps and blows off across the bench. Thats what happens with backwards hole flow.
     
  5. AC0FP

    AC0FP Ham Member QRZ Page

    ?????????????????? Damn, second post this week that I've found something I must have missed (slept through) in Electronic Fundamentals 101. I have been laboring all these years thinking if you hook up a diode backwards nothing happens!:D
     
  6. KI6DCB

    KI6DCB Ham Member QRZ Page

    Here's something else to consider:

    Current flow is a statistical process, just like temperature. As we hook up a conductor in such a way as to make a circuit, the electrons come out of the end of the wire into the next circuit component, just like water comes out of the end of a full hose when we turn on the tap. Consider, though, that they are not the electrons that just left the cathode of the source at that instant, just like the tiny particles of water that initially squirt out of the [full] hose are not the ones that "just now" came from the tap. Indeed, the current flow through the circuit is an average of the number of electrons moving toward the anode at any given time. The electrons that leave the cathode get to the end of the wire faster than the water molecules get to the end of the hose, of course...unless the wire is very long and/or the hose is very short.

    Some of the electrons, however, are pretty lethargic at any given instant. As a matter of fact, the energy levels of the electrons vary from zero (very few of them) to very nearly the speed of light (also very few of them). The average energy is determined by the pressure (voltage) and the resistance of the wire. Most of the electrons are moving along at a pretty good clip -- the mean velocity is not far below the very fastest electrons -- but the energy levels, hence the velocities, are distributed at all possible levels.

    That's why electrons zipping about make random electrical noise. As resistance increases, radiated noise becomes more pronounced due to the varying electric and magnetic field strengths generated by the varying electron velocities interacting with the environment; conducted noise increases because of the random nature of the instantaneous number and varying speeds of electrons flowing through the [circuit/transistor/speaker/insert component name here]. The greater variation is due to more electrons striking more obstacles and slowing down, only to be accelerated again by the EMF. The resistance is a direct result of the electrons being slowed on their journeys by crashing into things; resistors simply have more things into which to crash than conductors have.

    This is why resistances become hot. The electrons, in colliding with the tiny things in the resistance, cause those particles to vibrate a bit; and, as the mean level of vibration increases, well, that's what we measure when we take something's temperature. It is also why the electrons come out of the resistance with, on average, less energy than when they entered; they imparted some of their energy to the atoms and molecules which they left behind, vibrating away. Arcs are pretty hot, and they have extremely wide variation in the electron velocity and path length, and that's why they make a lot of electrical noise.

    As temperature approaches absolute zero* the noise levels drop off precipitously because all of the electrons are slowing down, decreasing the spread between the maximum and minimum velocities. As the energy levels converge upon the mean, the noise level decreases until, at the limit, quiet is obtained because all electrons are at the same velocity. Unfortunately, complete quiet is achieved only at absolute zero, where the mean velocity is zero. With no movement we can't get any work done, so a completely quiet circuit is not, at this time, possible. People are working on this, though, and, sooner or later, a breakthrough will probably occur.

    *"Absolute Zero" was a pet name given to me by my first wife at the end of our marriage; I don't know why she left me if she thought I was "that cool". ;-)

    Thank you for your time reading this.


    Ed -- Explaining physics, mostly to myself, for fifty years and counting.
     
    Last edited: May 24, 2008
  7. K8MHZ

    K8MHZ Ham Member QRZ Page

    That is exactly why darkness emitting diodes work as well. (Some folks still call them 'photocells'). *So* old school.

    :D
     
  8. KI6DCB

    KI6DCB Ham Member QRZ Page

    Bravo! Great signature line, by the way.
     
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