Electronics > Electronics

philosophical question

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ErikY:

--- Quote from: waltr on January 24, 2013, 08:32:26 PM ---
--- Quote ---If I understand correctly, there is a formal rule that current (stream of electrons) flows from (+) to (-),
--- End quote ---

False, in electronics the typical notation is the current flows from (+) to (-). This has been arbitrarily agreed upon and it fact it does not matter which direction used for the notation of current flow as long as it is consistent.

--- Quote --- electrons flow from (-) to (+).
--- End quote ---

True- but this fact is not really needed in the study of electronic circuits. This fact is however required in the study of semiconductors.

--- Quote ---we know that the real current flow is reverted, but were are building circuits like if the formal flow was the real one.
--- End quote ---

Again, Current flow is arbitrarily determined. Electron flow is from the negative source, through the circuit to the positive source. Do not confuse the two as being the same.
Current flow is just a notation whereas electron flow is Physics.

--- Quote ---My question boils down to this: shouldn't we be connecting all cathodes together instead of anodes?
--- End quote ---

Circuits can be built either way and some circuits have both.
Consider circuits that have a signal that varies above and below the 'common' or zero potential. AC coupled Audio is a common type of signal. For example:
http://www.allaboutcircuits.com/vol_6/chpt_6/10.html
This circuit has a 'common' (Ground) and a two supplies (voltage sources), one that connects to the 'common' and +V, the other to the 'common' and -V. For the top half of the circuit the supply is positive with respect to the 'common' but for the bottom half of the circuit the supply is negative with respect the the 'common'.

--- End quote ---


This has been something that has been bothering me as well, ever since reading allaboutcircuits.

I have to say, I have searched for an explanation or understanding of this, and by far this is the absolute best response I have seen.

This is really helpful, and really clears up  lot for me!

jkerns:

--- Quote from: redloff on January 24, 2013, 04:22:04 AM ---My question boils down to this: shouldn't we be connecting all cathodes together instead of anodes?
Since the formal current flow is reverted, the zero potential should be (+) while number of electrons cumulated on (-) side of the power source should determine the voltage value.


--- End quote ---

Stick to driving English cars from the '60s and older and you won't have to worry about this since they used positive for the ground.

What really matters is that there is a path all the way around the circut from source through the load and back to the source. It doesn't matter what point in the circuit you call "ground" but using one end or the other of the source as ground is convienent. And, picking the negitive end is even more convienent since that is how a lot of equipment happens to be wired.

Just try findinga radio for a vehicle with positive ground... ;)

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