Just a comment:

Follow the arrows, the diodes, transistors, etc. That's the path.

The flow analogy will break down.

Conventional current doesn't change the analysis. It does, however not explain well how electron tubes work, how CRT deflection works, solid state physics an electro-chemistry. In solid state physics, we have the concept that "holes" are conventional current. For the physics to work for electrons in vacuum or electro-chemistry we ave to flip gears.

I challenged a teacher that my answer was indeed correct an it should not be marked wrong. He agreed and said, "Your not suppose to know that yet."

You can't take into account of all of the nuances in an electrical circuit, but you sometimes have to understand the role of parasitics. Physics helps you understand that.

Moving a wire int the Earth's magnetic field generates a current. Does the average Joe have to worry about it? No. I, however, in my job had to. You will learn that three resistances in series is the sum of each, but a single resistor is a very different component than the series combination. In some cases it matters that a SMT resistor is mounted on it's edge rather than flat. It's a different component. Short and long leads protruding make the components different.

Also learn that Power P is power dissipated and negative power is power generated. To analyze a 4 MW power system, the generator must be generating -4 MW.

The current is the same in all series elements.

Placing a voltmeter in a circuit generally disturbs the circuit. Putting an ammeter in a circuit to measure the current and taking it out to measure voltage will generally not give you the right result.

 

Whether the resistor is before the LED or after - makes no difference. Now, if you put it before the transistor then you're changing how the circuit works. But to your point about whether the LED will see the full voltage if the resistor is down stream of the LED is mistaken. The LED is slightly dependent on voltage but highly dependent on current. If you restrict the current the LED is happy. If not then the LED will die.

 

The simplest LED flasher is simply to use a flashing LED. The problem with that approach is you have no control over the flash rate, but it does have its use for eye catching displays for selling stuff.

 

See

 

Look at my models. Models with the suffix _L have parameters in the reverse mode close to the theory and normally operate at lower currents.

 

I think that the diagram below is of interest as a textbook.
See

 

Use NPN_Avalanche.asy from Avvalanche.zip (one symbol - many models)

 

I quickly scanned the replies and did not see a short straight forward one. If I missed it then I apologize

SCHEMATICS: It does not make any difference as long as you use the same thought (system of thinking) through out the entire diagram. The arrowhead of a schematic ALWAYS represents the presence of a PN junction, the direction of that arrow always pointing in the direction that conventional flow would go if the junction were forward-biased. Therefore, schematics are for conventional flow and formulas.

MATH: (I edited out "Electrons" per the scathing comment by Mr. WBahn who is apparently unable to understand the intent - see below) [Insert] "Electricity" was originally thought to travel from positive to negative - like gravity or water pressure. So for several centuries math formulas were developed that worked with this assumption. Later it was found that electrons where negatively charged and therefor moved towards a positive charge. "Technicians" (someone holding a soldering iron) continued to use the existing formulas (which work fine), but mathematicians, Phd's, and Doctorate papers like to think of themselves as perfectionist, began to use a different (except for a few instances, literally reverse) set of formulas due to political and peer pressure.

It is interesting that mathematicians and theorist are willing to simplify explanations by assuming a electron is a particle in a Newtonian or magnetic orbit (which it is not), yet choose to be purists in other areas rather arbitrarily.

CONCLUSION: Schematics are written for "technicians" and the people who actually use a circuit, while Doctorate papers and their set of reverse formulas are for the folks working at CERN.

[This was edited because Mr WBahn is apparently offended by the use of vernacular language when attempting to simplify a topic of discussion.]

 

MATH: Electrons were originally thought to travel from positive to negative - like gravity or water pressure. So for several centuries math formulas where developed that worked with this assumption. Later it was found that electrons where negatively charged and therefor moved towards a positive charge. "Technicians" (someone holding a soldering iron) continued to use the existing formulas (which work fine), but mathematicians, Phd's, and Doctorate papers like to think of themselves as perfectionist and began to use a different (except for a few instances, literally reverse) set of formulas due to political and peer pressure.

It is interesting that mathematicians and theorist are willing to simplify explanations by assuming a electron is a particle in a Newtonian or magnetic orbit (which it is not), yet choose to be purists in other areas rather arbitrarily.

Boy, do you need to spend some time with some history books.

People assumed for several centuries that electrons traveled from positive to negative? Really?

Let's see, the electron was discovered by JJ Thompson in 1897 (for which he won the 1906 Nobel prize).

The definition of positive and negative charge was made, arbitrarily, by Benjamin Franklin well over a century earlier -- sometime around 1750 -- when he chose to call the net charge on a piece of glass rubbed with silk positive and the silk itself negative. This was a fairly reasonable thing to do since it seems more likely that the "electric fluid" would more easily flow off the soft silk and onto the hard glass than the other way around.

People that use electron flow invariably end up having to invoke magical mystery minus signs because they fail to make the distinction between the flow of charge and the flow of charge carries.

If you start with an initially uncharged object, say the shell of a Van der Graaf generator, and build an electric charge by having 1 ampere of current flow onto it for 1 second, what is the charge on object? Since, by definition, one ampere if one coulomb of charge per second, there would be 1 coulomb of charge, meaning that it is positively charged. But the electron flow people insist that one ampere of current flowing onto the object means electrons are moving onto the object and so, magically, it ends up being negatively charged despite having a positive amount of coulombs flowing onto it.

 

@ThirtyWest

For whatever it's worth at this point, and this is MY own opinion also... no denigration intended to anyone on any level...

Did Ron really nail this one straight on the head (back in Post #4) or what?!

Keep going. Keep trying. Ultimately it really does not matter what analysis tools you use. If it helps you to get a better grasp on how circuits behave, use any flow business you like! Don't get hung up on trivialities. If you are planning on making a career of electronics technology, there will always be plenty of worthwhile things to get stuck on.

Just my opinion ... don't want to anyone off.
-cf-

 

Why do you get hooked on an electron, as a carrier of a charge. There may be other carriers of charge. Take for example water (not very clean). Of the water ice made a transistor, though very slow. The charge carrier can also be a positron.

 

Why do you get hooked on an electron, as a carrier of a charge. There may be other carriers of charge. Take for example water (not very clean). Of the water ice made a transistor, though very slow. The charge carrier can also be a positron.

You're going to have to explained that to me like I'm a six year old because I don't get it at all.

 

I understand the difference between conv and elec flow. The part that is confusing, for someone learning to read schematics, is which is which on the paper?

To answer your question; current flows in the direction the arrows are pointing. Diode, transistor and anything else with an arrow - current flows in that direction.

There are devices that have arrows in both directions, such as a Triac. Current flows in both directions because it is used in AC circuits. When current is flowing on one direction the triac when controlled by a controlling source allows the current to flow in that direction (at the instance the sine wave is going).

As for "Which is which on the paper?" the answer is "Conventional flow".

 

Water (ordinary, not heavy) has the formula H2O. It contains hydroxyl ion OH- and proton H +. These ions and participate in the electrical conductivity of water, rather than free electrons. Ice represents something like a semiconductor. Adding an acid or alkali can make materials in which the main carriers are protons or hydroxyl ions.

 

Water (ordinary, not heavy) has the formula H2O. It contains hydroxyl ion OH- and proton H +. These ions and participate in the electrical conductivity of water, rather than free electrons. Ice represents something like a semiconductor. Adding an acid or alkali can make materials in which the main carriers are protons or hydroxyl ions.

Thanks man the last chemistry class I took was 17 years ago and it was chemistry 101 so I didn't really see the parallel.

 

Boy, do you need to spend some time with some history books.

According to "Modern Marvels" the Romans used and built simple batteries. For several hundred years prior to the discovery of the electron, people like William Gilbert in his book De Magnete in 1600 coined the term "electricity" and folks like Benjimin Franklin in 1759 were discovering its properties. The common belief was that it was a "invisible" fluid like water and flowed "down hill" or somehow traveled from a high pressure to a low pressure like water. I suggest you read YOUR history books before you are critical of others!

 

"Modern Marvels" is the definitive electrical history series.

Maybe they used them to power lights for alien runways or maybe they were what most actual archaeologist believe, a sealed jar containing the metal remnants of a scroll.

https://archyfantasies.com/2012/06/...zzling-ancient-artifacts-the-baghdad-battery/

 

According to "Modern Marvels" the Romans used and built simple batteries. For several hundred years prior to the discovery of the electron, people like William Gilbert in his book De Magnete in 1600 coined the term "electricity" and folks like Benjimin Franklin in 1759 were discovering its properties. The common belief was that it was a "invisible" fluid like water and flowed "down hill" or somehow traveled from a high pressure to a low pressure like water. I suggest you read YOUR history books before you are critical of others!

Your claim: "Electrons were originally thought to travel from positive to negative - like gravity or water pressure. So for several centuries math formulas where developed that worked with this assumption."

So how is it, per YOUR claim, that people believed that electrons flowed from positive to negative for centuries before the electron was discovered and before positive and negative were even established?

 

"Modern Marvels" is the definitive electrical history series.

Maybe they used them to power lights for alien runways or maybe they were what most actual archaeologist believe, a sealed jar containing the metal remnants of a scroll.

https://archyfantasies.com/2012/06/...zzling-ancient-artifacts-the-baghdad-battery/

A little necro.