Why is plus on top?

[Jim Patchell]

Paul Perry wrote:

> At 10:39 AM 17/04/00 +0100, neil johnson wrote:
>
> >I think it dates back to valves.  Most valves have the anode at the top of the
> >envelope mostly, I think, due to the construction of the device.  This leads to
> >the natural step of drawing the valve with the anode at the top and the cathode
> >at the bottom.
> Actually, most have a grid at the top. More than anodes, anyway.
> And, if negative had been put at the top in schematics, valves wd have
> been deawn 'upside down'.

Now you see, I have the oposite problem.  I grew up in the early '60's, when
germanium transistors were the state of the art.  Most of them were PNP.  All of the
schematics that used primarily PNP transistors had negative at the top.

>
> I think it comes from the natural tendency to think + is "higher", like when
> you label the side of a graph.
> Of course, 'holes', lacking an electron, are a bit 'lighter', so....
>
> Really, I think the fact that the 'large' voltages with respect to earth being
> positive in valve gear is what made the + on top convention stick.
> You aren't gonna put those 'big' voltages on the bottom, are ya?
> And, all that '+' electricity is trying to 'flow' to earth, and everything
> flows 'downhill'.
>
> paul 'downunder' perry melbourne australia

    -Jim