[R-390] Current direction

[jcoward5452 at aol.com]

If electron flow in a vacuum tube did not flow from cathode (negative potental) to anode (positive potental) then the suppresor grid would be placed at the cathode and not the plate.IIRC the supressor grid was to attract electrons that actually bounced off the plate and then impacted again causeing noise.This grid would draw off those errant electrons and thus improving the noise figure of the tube.
?In semiconductor materiel,there is electron flow and what some call "hole" flow.There are atoms with excess electons and atoms that are lacking electrons.As current flows, electrons move to an atom lacking electrons.The atom loseing electrons?is now a "hole" and thus there is a "flow" of holes positive to negative and a "flow" of electrons negative to positive.
?Of course this is an oversimplification.One must understand atomic physics to get a grasp of semiconductor theory.And atomic physics is always in a state of flux.
?I stick with vacuum tubes because I find them more understandable from a layman's point of view and with my R-390A operating I do not have to heat my workroom!
?Jay KE6PPF


-----Original Message-----
From: Jim Haynes <jhhaynes at earthlink.net>
To: Roy Morgan <k1lky at earthlink.net>
Cc: R-390 LIST <R-390 at mailman.qth.net>
Sent: Fri, 20 Mar 2009 8:25 pm
Subject: [R-390] Current direction



On Fri, 20 Mar 2009, Roy Morgan wrote:

> If I remember correctly, at one time the Navy, and possibly other
> services too, taught basic electricity with the idea that the current
> flowed in the direction of electron movement.  So, the positive
> terminal of a battery would be shown with the  current *entering* that
> terminal.  Then, there was a reconciliation with the rest of the world
> and all the training materials and schematics and so on got changed.
> This likely was before WW-II: I don't have any examples of that
> convention.
>
When I was an E.E. student in the late 1950s the texts all showed
"conventional" current flow, positive to negative.  At the time we had
a lot of veterans and particularly the Navy ones were vociferous that
the texts were all wrong and that current went with the electrons,
negative to positive.  It was hard to get them to realize that it
doesn't really matter so long as you are consistent; the answers
will be the same either way.  (It's not the same as believing that
Niagara Falls will flow uphill!)

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