# A Commuter Diode Explanation Problem

1. Jun 7, 2005

### cybershark5886

I have been trying to figure how a commuter diode effectively works in a circuit with a coil. I know that once the electric/magnetic field collapses in the coil after the current is cut to it that it induces a current in the opposite direction on the diode, which can only travel one way. But when trying to read up on an article with diagrams on this fairly simple circuit, I either got really confused or the people drew the diagram wrong.

Check out this very small article to see what I am talking about: Inductor commutating circuits.

Shouldn't the 4th diagram (the post-collapse diagram) have the current arrows going in the opposite direction and the polarity signs on the diode switched (thus staying the same in the 3rd diagram - because the diode cannot switch polarity)? Or am I just reading it wrong. The current in a diode travels in the direction where the arrow symbol points, right?

Maybe one of you could help me out in trying to understand how that circuit works. It seems simple but I can't figure it out with that article.

Last edited: Jun 7, 2005
2. Jun 8, 2005

### willib

there is such a thing as conventional current flow and electron flow theory ,
http://www.mi.mun.ca/~cchaulk/eltk1100/ivse/ivse.htm [Broken]
this site explains the difference..in engineering we use conventional current flow..
your site uses the other system..
in conventional curent flow , the current flows out of the positive battery terminal..

Last edited by a moderator: May 2, 2017
3. Jun 8, 2005

### Dngrsone

The diagram is correct when viewing from an electron flow perspective. Frankly, I've not met anyone who uses "conventional" current flow, but that may just be due to the community I work in.

Just ignore the arrows and follow the polarity signs, maybe that will help.

4. Jun 9, 2005

### willib

man this place is dead.
i thought it was bad before , but holy crap its positively comatose !!
Dngrsone, really ? we sort of learned both ., but conventional was by far the majority..
it must be weird when using diodes, having to go against the arrow ,all the time..??

5. Jun 9, 2005

### Gokul43201

Staff Emeritus
I too have rarely come across electron flow (as opposed to conventional current) pictures, but that's clearly what the site linked by the OP is doing.

6. Jun 9, 2005

### Dngrsone

We learned that the arrow pointed to the N-doped silicon :uhh:

Conventional theory was briefed to my class, but we were taught electron flow theory because it's the way electronics "really works" and also because it's almost indispensable for vacuum-tube theory, which we learned before going into transistor theory.

My instructor was a hard scinece/physics type, so he taught us how everything worked according to the reigning knowledge of the day. I have since relearned things a little differently (but clearer in my brain) here. Keep in mind, this is still electron flow theory.