electical flow question. - Page 1
Forum section: electronics / beginners

author: whitevamp
author_rank: Regular Contributor
timestamp: June 02, 2017, 02:43:58 am
content: ok lets see if i can write this so that it makes sense.ok i understand that depending on who you ask the flow can ether be from positive to negative, or ( the proper way, from my understanding.) negative to positive.but that brings me to the question of if it is negative to positive then how dose it flow through a diode? EG: you have the negative of the diode to the negative and positive to positive, but the diode is suppose to stop that flow in that direction.or am i over thinking it.

author: jeroen79
author_rank: Frequent Contributor
timestamp: June 02, 2017, 02:47:46 am
content: https://www.allaboutcircuits.com/textbook/direct-current/chpt-1/conventional-versus-electron-flow/

author: mdszy
author_rank: Unknown
timestamp: June 02, 2017, 02:53:23 am
content: When I was first starting out, I had the exact same confusion.I won't try to explain the differences, but I'll give you the short answer that will keep you from being confused, even though it doesn't really explain anything. You can research elsewhere for the differences.Think of current as flowing from Positive to Negative. That way, it flows through diodes in the direction their schematic symbol "points".Honestly, that's about as simple as it can be, if it makes it easier. When you're doing circuit analysis/design, there's no circumstance (at least not that I can think of) where you have to worry about conventional vs. electron flow.Hope this helps!

author: whitevamp
author_rank: Regular Contributor
timestamp: June 02, 2017, 03:15:30 am
content: ok so basically just ignore Electron Flow and stick to Conventional when looking at and designing a circuit.

author: AG6QR
author_rank: Frequent Contributor
timestamp: June 02, 2017, 03:15:51 am
content: Quote from: mdszy on June 02, 2017, 02:53:23 amIf you're working with CRTs, it seems natural and intuitive to think of the electrons flowing out of the electron gun and crashing into the screen to light it up, but the conventional current flow model would have the current going from the screen to the back of the tube. Similarly, when you work with vacuum tubes, to intuitively grasp why the heated filament goes on the cathode and not the anode, you need to know about electron flow, not current flow. Finally, with transistors, to understand why the "emitter" typically collects conventional current and the "collector" typically emits conventional current, it helps to understand the electron flow.But you're right; in the big picture, you can normally ignore electron flow, and just go with the conventional current flow model, where current flows from positive to negative. That's the way most people work most of the time, and as long as you're consistent, it generally works just fine. For most purposes, thinking about electron flow just needlessly complicates things.https://www.xkcd.com/567/

author: basinstreetdesign
author_rank: Frequent Contributor
timestamp: June 02, 2017, 05:16:41 am
content: Quote from: whitevamp on June 02, 2017, 03:15:30 amYes; you can theoretically pick one or the other and use it consistently and everything you design can work but to be consistent with most other people, conventional current flow is best.

author: Brumby
author_rank: Unknown
timestamp: June 02, 2017, 11:45:57 am
content: As said above - one is conventional current flow and the other is electron flow.My suggestion is understand what electron flow is, especially for valve (tube) operation - and then forget about it. Use conventional current and you will be fine for just about everything.

author: whitevamp
author_rank: Regular Contributor
timestamp: June 02, 2017, 02:46:41 pm
content: Quote from: AG6QR on June 02, 2017, 03:15:51 amok.and that's good to know about the way it flows / works for those instances.and thanks for the link.Quote from: Brumby on June 02, 2017, 11:45:57 amsound good.

author: retrolefty
author_rank: Super Contributor
timestamp: June 02, 2017, 03:27:01 pm
content: It really makes no difference for someone established and experienced in electronics. However they obtained their preference for whatever reason, as long as s/he is consistent in their usage it doesn't really matter.The only issue is if that person gets involved with training others. Should s/he teach their preference or that of the the organization they represent?What if they are charged with creating lesson plans with free choice of flow preference?

author: TimFox
author_rank: Super Contributor
timestamp: June 02, 2017, 04:38:35 pm
content: For a semiconductor diode, remember that the "arrow" points in the direction of conventional current flow when the diode is forward-biased. Since Zener diodes are operated in reverse bias (breakdown), normal operation reverses that statement, but the real diode will still be forward-biased (much lower voltage) when current flows along the arrow direction. Similarly, the arrow on the emitter of NPN or PNP bipolar transistors points in the direction of normal current flow.

author: schmitt trigger
author_rank: Super Contributor
timestamp: June 02, 2017, 04:59:27 pm
content: This question has been asked repeatedly on the electronic forums that I wander around.Actually, the responses in this forum have been so far very polite, compared to the endless flame wars I've witnessed elsewhere. Kudos for that!Like other posters, when I work with "pure" vacuum tube circuits, electron flow makes all the sense. Otherwise, it is conventional current flow.Having said that, most younger electronic enthusiasts likely have never worked, and probably will never work, with a "vacuum state" device. Their last stronghold, the CRT, has by now been replaced by LCD or LED screens.

author: Ratch
author_rank: Regular Contributor
timestamp: June 02, 2017, 05:10:38 pm
content: Quote from: whitevamp on June 02, 2017, 02:43:58 amConfusion arises because there are two charge carriers in the universe, positive and negative. I will explain how to calculate without confusion. First of all, current does not flow. Current means charge flow and current flow means the ridiculous "charge flow flow". Everyone should say charge flow, current exists, or current is present to be correct, but not current flow.The so called "conventional current" is really a mathematical convention. It assumes that mathematically, all charge carriers are positrons, not electrons. That means that a battery mathematically emits positive charge carriers from its pos terminal and receives positive charge carriers at its neg terminal. Do all your calculations based on that proposition and find an answer. If it is really necessary to know the actual physical direction of the current, then reverse the calculated current if the charge carriers are negative, or keep the same direction if the charge carriers are positive, like semiconductor holes are. That's all there is to it. You will really get wrapped around the axle if you first ask, "What is the polarity of the charge carriers?" "Are they positive or negative?" Most of the time it is not necessary to know. Do your analysis using the mathematical convention method.Voltmeters and ammeters are marked according to the mathematical convention. A positive voltage on the pos terminal causes a meter deflection in the forward direction. Semiconductor manufacturers also mark their components using the mathematical convention. A positive voltage on the diode arrow allows conduction to occur.Ask if you have any questions.Ratch