Here's where the whole problem began for me (there's a question at the bottom). I'm reading one of the NEETS training manuals where it describes DeForest's experiments with triodes. This is the first of two graphics they use, this one showing how changes in grid voltage result in more or less electron flow across the void in the tube:Admittedly, 10 years old seems too young to get into too much detail, so some basic understanding of voltage combined with the concept of current flow may be useful and sufficient. Even when water flow is considered, the idea of pressure is needed to really get the gist of what is happening, and voltage is analogous to pressure.
Their description goes like this:
"It’s the old principle of 'opposites attract.' When the control grid is made positive [fewer electrons on it], electrons surrounding the cathode (negative charges) are attracted to the grid. But remember, the grid is a metal mesh. Most of the electrons, instead of striking the grid wires, are propelled through the holes in the mesh. Once they pass the grid, they are attracted to the positive charge [fewer electrons] on the plate."
And I was getting it. Loving it, in fact. What could be simpler? All we need to worry about is electrons and the fact that they don't like to be near each other. So I turned the page, expecting that I would find out what happened to those electrons after they hit the plate and exited the tube. I found this diagram with plate resistors added:
Which was fine, because I had seen a similar configuration of parts in many guitar amp circuits. What was not fine was the description because it unexpectedly (and in my mind, unnecessarily) abandoned the electron-flow paradigm:
"Instead of amplification, De Forest had obtained 'conversion,' or in other words, converted a signal voltage to a current variation. This wasn’t exactly what he had in mind. As it stood, the circuit wasn’t very useful. Obviously, something was needed. After examining the circuit, De Forest discovered the answer—Ohm's law. Remember E = I × R? De Forest wanted a voltage change, not a current change. The answer was simple: In other words, run the plate current variation (caused by the voltage on the grid) through a resistor, and cause a varying voltage drop across the resistor."
And I thought to myself, Why didn't they simply continue describing the electron flow? Why talk about a voltage drop across the plate resistor when it's what's happening at the bottom of the resistor -- ie, the output of that stage of the amp -- that's of interest to us? In short, I thought they should have said something like this:
"If we put a resistance in the way of all those exiting electrons, it will obviously create 'congestion' or a 'bottleneck' at the bottom of that resistor. We will thus have a greater [negative] voltage (ie, a higher concentration of agitated electrons, all trying to repel one another) at that point -- the pressure increasing while the flow out of the tube continues, then decreasing as the electrons are able to eventually drain away through the resistor."
I think this latter description better for three reasons: first, because it doesn't change paradigm horses in mid-stream; secondly because it directly relates not only current but voltage to our little electron buddies; and thirdly because we can now predict what will happen, in a general sense, intuitively and without mathematics, if we change the value of that resistor (specifically, too much resistance will result in too much congestion and thus distortion of the signal; too little resistance will result in the electrons rushing by the "output" point and too little volume will result).
Question: Is that essentially what happens with those exiting electrons? If not, exactly what does happen to them?
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