Current can be thought of as flowing in both directions because there are
two charge carriers. The negative charge carrier is the electron, it flows
from - to +. The positive charge carrier is the "hole", which is the absence
of an electron. When an electron jumps from atom A to atom B to fill a hole
in atom B it also leaves behind a hole in atom A. So the hole is thought to
travel from + to -. This is conventional current.

-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Vasile Surducan
Sent: Thursday, July 18, 2002 5:29 AM
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [EE]:VCC,VDD,VSS ...


On Wed, 17 Jul 2002, Russell McMahon wrote:

> Examples:
>
> 1.    PIC supply
> VCC (or VDD)  = +5 volt
> Negative supply = VSS = Gnd = 0 volts
>
> 2.    OP AMP supply
> VCC = +5V
> Gnd = 0v
> VSS = neg = -5 volts
>

  Does the current flow in any circuit from + to - or this is just in our
minds ? because our teachers say that and the teachers of our teacher said
us the same ?
This is just a model so let your brain to fly away from...


the following will work perfectly if you know how to interface it:

> 1.    PIC supply
> VCC (or VDD)  = 0 volt
> Negative supply = VSS = -5V

also: PIC supply
Vcc = +205V
GND = +200V
HVGND = 0V
be sure it works, until you don't try to command a load connected from
IO pic pin to HVGND.

VCC, VDD, GND, VSS, VEE are things invented by humans to complicate their
lifes, or just to standardize something which can't be standardized.

best regards, Vasile
http://www.geocities.com/vsurducan

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