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Re: tube coils

Tesla List wrote:
> 
> >From major-at-vicksburg-dot-comThu Sep  5 22:18:48 1996
> Date: Thu, 05 Sep 1996 18:26:27 -0500
> From: RODERICK MAXWELL <major-at-vicksburg-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: tube coils
> 
> I have not even finished my first capacitor discharge tesla coil and already I,m
> looking forward to building a tube driven coil! I've odered a couple of books from
> I.T.S. __Vacuum Tubes In Wireless Communication__ by Elmer E. Bucher ,and __Vacuum Tube
> Tesla Coils__by J.F. Corum and K.L. Corum. I have built several high voltage projects
> using induction coils and a solid state Mosfet driver, but I have never built
> __anything__ that uses tubes.
>   In __Vacuum Tubes In Wireless Comunication__ it describes the vacuum tube as a
> rectifier. It also shows the direction of electron flow from the filament to the plate.
> This part I comprehend and understand well. What I have a hard time visualizing is
> current flow from the plate to the filament! If the flow fom the filament to the plate
> is composed of electrons, what is current flow from the plate to the filament composed
> of and what is the mechanism that allows this to happen? Is it simular to hole flow in
> semiconductor material???? Could someone that has experience with tube electronics
> please answer these questions for me so I can sleep nights?


We are all "shabby, shabby bastards"  (Monty python - life of bryan)

We have always been at the mercy of teachers.  They have done their best 
to illiterate and give us warm and fuzzy feels for the mechanism behind 
electrical and electronic goings on.  In doing this they have educated us 
and left some of us with false impressions.  The only real world fact is 
that electrons do, indeed, leave the heated cathode and flow to the plate 
in a vacuum tube.  I was of the very old school and learned electron flow 
for the sake of vacuum tube education (- flows to +). 1950's.  With the 
transistor coming on strong while in college, I had to learn current 
flow to mesh with the quantum goings on in semiconductors (+ flows to 
minus) 1960's.  Either one is usable if you keep your wits about you.

I was fortunate to learn both and am not confused by them.  There is a 
deeper understand here.  There are no holes in real life and the 
semiconductor models we are taugh are conventions and not fact!  They 
help us grasp and use the semiconductor in circuits.  The understanding 
we receive is an valuable and highly useful illusion.

The important thing to remember in current flow is that in tracing out a 
circuit we always "fall" from a high potential (+) to a lower one (-).  
This leaves all entry points on circuit components, positive and all exit 
points, negative.  Electron flow is all but disgarded now and is only 
readily obvious in tubes.  This is the only place in electronics where we 
can really be sure of what is really happening on even the most 
microscopic scale!!  It was always hard to envision a voltage climbing up 
to a higher potential through a resistor. Even way back then.  The 
current flow model is more intuitive.  Forget that "nothing" in the 
current flows through the tube in the reverse direction, it is just a 
convention which must be obeyed if you are to use it well.  In everything 
electrical, we are really only moving phantom charges about.(except in a 
vacuum tube)
  In copper wires, electrons do flow, but only very very slowly. 

Richard Hull, TCBOR