Idealized grounding arrangement per Merlin!

[R.G.]

And I was wondering if "smoothing" was a more British way of speaking, or is it accepted engineer-speak? I am aware of all those boots, bonnets, tappets, spanners (and even valves!) that don't mean what I thought they meant.

Yeah. Leave a call with the desk to be knocked up in the morning.

[Wilder Amplification]

What I never understood about Merlin's book (along with the current trend that seems to have become prevailent amongst techs in recent times) is that he teaches from the standpoint of "conventional current flow", yet this is electronics, which deals with ELECTRON flow and makes much more sense when you're dealing with electron valves anyway. Why conventional current flow?

[Tonewood]

smoothing

And I was wondering if "smoothing" was a more British way of speaking, or is it accepted engineer-speak? I am aware of all those boots, bonnets, tappets, spanners (and even valves!) that don't mean what I thought they meant.

I guess so:

Capacitative Smoothing

[Rick Erickson]

All this discussion of safety grounding and the dangers of lifting grounds, live mics etc. reminds me why I bought the best true diversity wireless system I could afford. No cable between my guitar and my amp. Problem solved.

[Merlinb]

And I was wondering if "smoothing" was a more British way of speaking, or is it accepted engineer-speak?

Yes, it is a more British term. In the US I think you use "filter cap" more often. However, I find it very useful to distinguish between the first cap which is for raw charge storage (the reservoir cap) and the others which are for hum reduction and decoupling (smoothing caps), as it makes it clearer exactly what is being discussed. Plus you get a nice mental picture of what the cap does, from the name, whereas just about any cap could be called a 'filter cap', whether it is in the power supply or not.

What I never understood about Merlin's book (along with the current trend that seems to have become prevailent amongst techs in recent times) is that he teaches from the standpoint of "conventional current flow", yet this is electronics, which deals with ELECTRON flow and makes much more sense when you're dealing with electron valves anyway. Why conventional current flow?

Because the actual direction of theoretical charge carriers is irrelevent. Electric current is by definition a flow of charge, not a flow of electrons. And why should they get all the attention anyway? What about positive ion flow in a gas tube, among others...

Bare in mind that 90% (I would guess) of the world's literature on electronics, in all languages, uses conventional current. And it is still taught that way in all European and Australian universities, AFAIK, and I have no desire to buck the global trend. The use of electron flow comes from the military schools I think.

Also, no-one actually thinks in terms of electron flow, even you.
What do I mean?
Electrons travel with hugely varying density and at different speeds (mostly extraordinary slowly, but also exceedingly fast in a valve) in different components around a DC circuit. What's more, in an AC circuit they do not flow at all, they stay still and vibrate by a sub-microscopic amount. Trying to reckon circuit operation in terms of the electrons would be an absurdly difficult and non-intuitive affair.
What you actually think in, is not electron flow, but negative charge flow, which is precisely equivalent to positive charge flow, AKA conventional current. It does not have a correct 'direction'.

If you could string up a billion light bulbs in series, and then connect them across a giant battery, you would see that the bulbs light up in sequence from both the positive and negative terminals simultaneously, they would appear to zoom down the line from both ends until they meet in the middle. Such a thought experiment immediately shows that the direction 'electric current' is not in any way related to the direction of electron flow, so why bother reversing what Benjamin Franklin has already decided? Such a move would be petty, and make life difficult for anyone reading the old literature.

Modern theoretical physics is moving in a direction where we will probably abandon the present model of electrons and the atom anyway. Electrons are not unquestionable particles, like marbles or something, and there no particular need to talk about which way they flow unless you design semiconductor junctions.

(Also, the diode symbols look like nice arrows that point in the direction of conventional current!)

[jmaf]

If you could string up a billion light bulbs in series, and then connect them across a giant battery, you would see that the bulbs light up in sequence from both the positive and negative terminals simultaneously, they would appear to zoom down the line from both ends until they meet in the middle.

Merlin, your example was creative but it does not help correctly illustrate the point you're trying to make here.

Tungsten emits photons("light") due to an excess electron energizing its orbit, thus the bulbs light up as electrons flow through the tungsten, not "charge", but an actual electron - one photon per electron in fact(physicists correct me if wrong).

Light bulbs thus are useful in demonstrating real electron flow, not conventional charge flow, they'd light up from negative to positive in a DC battery.

In fact, according to Gerald Weber on one of his books, DC heater voltage tends to consume one of the sides of the filaments first, the side that receives the electron flow. I don't have any personal experience with tube watching for 6 years to determine how the heck they burnt up.

[Merlinb]

Merlin, your example was creative but it does not help correctly illustrate the point you're trying to make here.
Light bulbs thus are useful in demonstrating real electron flow, not conventional charge flow, they'd light up from negative to positive in a DC battery.

I don't think you've thought about my experiment hard enough!

In all practical circuits, current is assumed to be set up in the whole circuit instantly. When when something happens instantly the notion of cause and effect -and therefore direction- start to lose meaning, which is just another reason why there is no reason to prefer the negative charge direction, but that's beside the point.
The idea of my thought experiment is to build a string of bulbs so long that current actually takes some time to be set up in all parts of it, so you could actually see the sequence in which the bulbs light. If you follow it through, you will find that the lights would start simultaneously from the +ve and -ve battery terminals, and finally meet in the middle of the string. Hence electric (charge) current (not electron current) can be reckoned in either direction with equal "correctness", and after all, it is what actually happen to our circuit components that we are interested in, not what is happening at the sub-atomic level.

Even if you still want to argue the point, you will still be in the minority. The rest of the world remains quite content with conventional current!

[jmaf]

I don't think you've thought about my experiment hard enough!

I did back in college some 14 years ago.

In all practical circuits, current is assumed to be set up in the whole circuit instantly.

The power-on transient is what makes them light up in series as you suggested, thus you created a theoretical long string of light bulbs to illustrate the point. I said it was a creative
example indeed.

When when something happens instantly the notion of cause and effect -and therefore direction- start to lose meaning, which is just another reason why there is no reason to prefer the negative charge direction, but that's beside the point.

I didn't prefer any direction, I just said tungsten lights up due to electron flow, it's not my opinion.

The idea of my thought experiment is to build a string of bulbs so long that current actually takes some time to be set up in all parts of it, so you could actually see the sequence in which the bulbs light.

I understood your idea from the start. You're creating a power-on transient to illustrate where charges appear during the transient.

I, in turn, corrected your example: light bulbs will NOT light up due to a presence of charge, but only due to electron flow so they light up from - to + no matter what charges appeared on the + side during the transient.

I also have doubts about the speed of light relation there and when exactly we'd see them light up, but I'm not Einstein and so I'll leave it to the physicists in the house.

If you follow it through, you will find that the lights would start simultaneously from the +ve and -ve battery terminals, and finally meet in the middle of the string.

They light up from negative to positive, because lightbulbs as I explained light up due to electron flow, not due to a charge appearing across them.

Hence electric (charge) current (not electron current) can be reckoned in either direction with equal "correctness", and after all, it is what actually happen to our circuit components that we are interested in, not what is happening at the sub-atomic level.

Yes, but the freaking practical real world tungsten filament vacuum light bulbs light up due to electron flow, so please choose a different device which lights up due to a theoretical charge or you're causing massive confusion in the minds of newbies around the globe.

Even if you still want to argue the point, you will still be in the minority. The rest of the world remains quite content with conventional current!

I did not question conventional current at all. I said your example was confusing for the reasons given.

I don't care being in a minority, as long as I'm right

[Merlinb]

They light up from negative to positive, because lightbulbs as I explained light up due to electron flow, not due to a charge appearing across them.

You still seem to have misunderstood me. You could use LEDs if you prefer, but it makes no difference. The sequence of lights would begin simultaneously at the +ve and -ve terminals and progress towards the middle, until there are all lit.

The very instant the circuit is closed, electrons being to move out from the -ve battery terminal, causing the first bulb to light. But they also begin to move into the +ve terminal at the same time, causing that bulb to light too. The electrons in the centre of the string are still stationary, so no bulbs are lit there, until the shunting effect eventually reaches all parts of the circuit.

You are correct that a valid model for wire incandescence is the movement of electrons though it, rather than charge, but the point is they start moving in two places at once, so the end effect (which is what we are actually interested in) can be reckoned in either direction.

Obviously you have to make your imaginary circuit extraordinarily large to appreciate this effect.

[jmaf]

You still seem to have misunderstood me. You could use LEDs if you prefer, but it makes no difference. The sequence of lights would begin simultaneously at the +ve and -ve terminals and progress towards the middle, until there are all lit.

The very instant the circuit is closed, electrons being to move out from the -ve battery terminal, causing the first bulb to light. But they also begin to move into the +ve terminal at the same time, causing that bulb to light too. The electrons in the centre of the string are still stationary, so no bulbs are lit there, until the shunting effect eventually reaches all parts of the circuit.

You are correct that a valid model for wire incandescence is the movement of electrons though it, rather than charge, but the point is they start moving in two places at once, so the end effect (which is what we are actually interested in) can be reckoned in either direction.

Obviously you have to make your imaginary circuit extraordinarily large to appreciate this effect.

Merlin, here is how electron flow happens:

http://image.funexpress.com/feimg/26_123.jpg

When the first electron leaves the - terminal of the battery, the whole row moves very slowly and knocks an electron off the other end. The desk balance balls are a very good analogy to teach your students.

That is, the whole row of electrons in your 2000 billion light bulbs move AT THE SAME TIME.

The only time you would be right would be during the transient, which you have discarded. In your example, the electrons all move together, the current is one and the same across any light bulb in the path, minus to positive terminal.

Having said that, I don't want to impose on you, so I recommend you disclaim that before one of your students builds a billion light bulb string just to prove me wrong. It'd be one heck of a waste.

PS. LED's emit light by electron flow AS WELL. Choose some other device, like mercurial gas or something like that, and I'm not sure about HG gas either.

[Merlinb]

When the first electron leaves the - terminal of the battery, the whole row moves very slowly and knocks an electron off the other end.

But I am talking about the transient period! The very moment when the switch is closed, and we are forced to watch the 'domino effect' of the first electrons starting to shunt the ones further down. The propagation speed, if you like, which is what the lights respond to. This begins from both the +ve and -ve terminals at the same time, and progresses away from the battery.
According to one of my textbooks, "one microsecond after you have made the connection, electrons nearly 330 yards along the line are starting to move."

Yes yes, the thermal lag of the filaments might spoil the impression. Use LEDs then.

[jmaf]

But I am talking about the transient period! The very moment when the switch is closed, and we are forced to watch the 'domino effect' of the first electrons starting to shunt the ones further down. The propagation speed, if you like, which is what the lights respond to. This begins from both the +ve and -ve terminals at the same time, and progresses away from the battery.
According to one of my textbooks, "one microsecond after you have made the connection, electrons nearly 330 yards along the line are starting to move."

Yes yes, the thermal lag of the filaments might spoil the impression. Use LEDs then.

OK prof. Merlin, you've really done it this time. I'm going to build this thing and show you!

No just kidding, I'm fine

My limitations don't let me go beyond what I've tried to convene, I don't know about electrons shunting each other and the current beginning like what you described, I thought it was an orderly process.

A techie like me debating with Merlin, it felt like I was trading punches with Mike Tyson here all along anyway.

[Russ]

Ok, here goes:

I think it depends on how the string is connected to the battery.

If the connection to the string is made at both ends simultaniously, then Merlin's scenario holds:
Electrons in the neg end of the string are repelled from the neg battery terminal, electrons in the pos end of the string are attracted to the pos battery terminal, and two electromagnetic waves (at about the speed of light) propogate toward the middle of the string until they meet in the middle and current flows steadily along the entire length of the string.

Remember, the electrons at one end of the string are repelled, while the electrons at the other end are attracted. So electrons at both ends experience the electromotive force. The electrons in the middle don't get the message until the wave arrives.

If the string is already connected at one end of to the battery and a switch is thrown at the other end to form the circuit, then the wave will begin at the switch and propogate back to the already connected end.

Basically, a wave of electromotive force propogates from wherever a connection is made.

But I don't think the circuit elements making up the string (bulbs, LEDs, etc.) matters.

The picture of the momentum thransfering balls isn't accurate because there is only a repulsion or push force involved, there's no attractive force happening at the other end.

Thanks for bringing this subject up. Hadn't really thought about it til now. Very interesting for such a basic circuit.

Russ

[Wilder Amplification]

I mean yes I'm sure the two charges (neg and pos) end up "meeting in the middle of the circuit" if you wanna really get down to it. But the textbook definition of electronics is "the study of ELECTRON flow" (hence the ELECTRON in ELECTRONics) whereas the definition of electricity is "the study of charge flow". When we're talking amps and tubes, we're talking about ELECTRONICS, but for some reason we speak of conventional current flow when we speak electronics and it seems that electron flow gets discounted completely.

That was the point I was trying to make.

[jmaf]

The picture of the momentum thransfering balls isn't accurate because there is only a repulsion or push force involved, there's no attractive force happening at the other end.

Russ, attraction and repulsion are one and the same thing, they're not two different forces in the system, they're the same force with a different referential. The battery is pushing and pulling at the same time and it's the same EMF all along the way, the two terminals are not doing two separate things.

Same thing with Merlin's example: it's one current, one movement, one EMF to light up the zillion bulbs.

In my example using the balls, my reference was all the voltage(ball height) on ONE end. With electricity it's the same, you can say -12 V + 12V looking from the middle or say + or - 24 V PP looking at one end, it's the same thing.

In the example, the desk balls had 24 Volts on one end, while you're saying they have +12 on one, -12 on the other.... Force is a vector, it has implied direction which we sometimes call attraction, sometimes call repulsion.

And you only have the attraction and the repulsion AFTER the circuit is closed, they do not exist independently before the switch is closed.

Don't discredit my balls just like that, they've got attraction too, it just depends .