Conventional and Actual Current on Schematics

3 quick questions:

Sources on the internet say that current flows from Anode to Cathode or Positive to Negative. Is this only true when thinking about a circuit in "Conventional" electron flow?

Is it reversed if we thinking of Actual Flow? Does current flow through from Cathode to Anode?

The symbol for a diode shows the arrow smacking into a wall, at first I thought it made sense to see that the "arrow" of the diode was pointing in the direction of flow. However, the notion of "Actual Flow" invalidate the symbol being used.

So if i am looking at a professionally published schematic for a product I just bought should I tihnk of the circuit in terms of Conventional flow since the diodes used in it show current flowing with the arrow?

 

You can think in conventional flow or electron flow as long as you make a conscious decision and be consistent. It's a matter of convenience.

Conventional flow assumes that something positive flows. The truth is, electrons flow, and they carry a negative charge.

When I look at a symbol for a diode, I see it as similar to a symbol for a speaker and the cone of the speaker emits electrons. Whatever floats your boat.

 

I picked up Paul Falstads applet and I mocked up a simple circuit and realized he is showing as a default Conventional flow.

I like the idea of the speaker cone. Thats what I thought of when I saw it.

Take a look at this diagram for reference to what I am about to say below:



So on the same topic, if I choose to think of things in terms of actual flow, then when I see a NPN transistor that is in series with a diode, then the Collector (as the Anode) is no longer receiving the electrons from the Diode's Cathode but is now Emitting them back through the Cathode on the Diode and back to the voltage source. Is that right?

It seems like the roles of the collector and the emitter would flip.

 

Ive hear this before. So if I choose actual flow then when I look at a published schematic, do I simply reverse everything in my mind when tracing the flow? For example, in the diagram I posted above, do I think of the electrons moving out of the negative side of the voltage source and into the Emitter of the NPN transistor and out the Collector? Where with Conventional flow, I would see electrons moving out the Cathode of the Diode and into the Collector of the NPN and out the Emitter...

 

For what it's worth - The US Army back in 1954 when I was in Field Radio Repair course was teaching electron flow.
Later about 1978 I was teaching a General License class for Ham Radio, and actually had a "Licensed Engineer" scream at me because I was teaching the wrong theory.
It makes no matter which method you use as long as you are consistent with the application.

 

I understand this gets brought up a lot, but I am asking if the function of the NPN transistors is reversed when thought of in "Actual Flow".

In Conventional flow, electrons flow through the collector and out the emitter, but in Actual Flow, since electrons are coming from the negative terminal of the voltage source, are the roles reversed where the collector is the arrow and the emitter is what is sending electrons to the diode (the bar side)?

 

Well yes for the NPN transistor the emitter "emits" electrons.
And collector "collects" those electrons.
For PNP emitter "emits" holes and collector "collects" those holes.

As for the current flow I prefer conventional current flow.

 

Lets just say I am using a NPN BJT. Reference the picture I linked to in a previous post. With actual flow isn't the Collector really the Emitter and the Emitter is really the Collector?

 

No, emitter always emits electrons in case of NPN transistor or holes in case of PNP transistor.
Also collector always collect electrons/holes.

In your circuit the electrons flow from negative battery terminal ---> emitter - collector-->LED---> 220R---> positive battery terminal

 

Don't even start thinking in terms of whether the collector collects and the emitter emits. You're setting a trap for yourself because that is inconsistent about whether you are using conventional (hole) flow or electron flow.

Being consistent is the most important tool.

 

Ive mocked this same schematic up in Falstad's simulator. His flow shows electrons moving from the + side of the voltage source through the 220R into the LED and Through the collector and out the emitter into the - side of the source. To me this is Conventional flow.

Is that right?

 

Yes the simulation show Conventional Current Flow from positive to negative terminal.
Simply Conventional Current Flow show how positive charge flow.
Electron flow show how a negative charge flow.
And you should stick to Conventional Current Flow if you want to avoid confusion.

 

Does AAC "textbook" (took me a while to figure out you were talking about this sites tutorials lol) teach actual flow then?

 

AAC show Electrons flow
http://www.allaboutcircuits.com/vol_1/chpt_1/7.html
But whether it is "actual flow" I don't know.
You must define what "actual flow" means for you.

 

I think it makes sense that current flows from high potential to low potential, i.e. positive voltage to negative voltage. The same is true for fluid flow, where fluids flow from high pressure to low pressure. I had originally learned on my own electron flow, but I was soon "corrected" when I entered into formal schooling.