Electron path of travel

[Wombaticus]

In early next year, I plan to release another video of my 36 watt combo amp ; with my new electronic volume control. If I posted the schematic for it, he will simply publish the design in one of his books.
-g

Bad news for you Gary. I'm guessing you haven't yet purchased a copy of Merlin's NEW book. But I'm a nice guy, so I'll give you a little preview: Chapter 10 is entitled "Voltage control". He must have used his wizardly ESP and mind-reading powers on you when you forgot to put on your tin foil hat for a moment or two.....

[Wombaticus]

And the idea that an amp is actually getting it's electrons from the ground references has served me very well as far as I can tell by performance.

No! The notion that ground references are somehow a well from whence the electrons spring up is a horrible misconception that leads to all sorts of errors in grounding schemes! The key concept to bear in mind that is in a properly grounded amp, there will be essentially ZERO current flowing through the (preferably unique) ground reference and the circuit ground. For instance, early on I myself had the grand misconception that the safety ground was the ultimate source of electrons for the whole amp. Believe me, this leads to all kinds of crazy stuff.

In my admittedly crude way of thinking about these things, I prefer to imagine the power supply rails and the grounds as collectively forming a big racetrack (or nested racetracks) with the same electrons zipping around and around the same ovals over and over again, propelled by the EMF from the PT. In a properly grounded amp, the ground reference(s) are a complete sideshow. That the ground reference is NOT required to provide electrons, one need only consider that the whole circuit *could* be just left floating, and would still more-or-less work.

[EDIT FOR CLARITY: above where I said "..essentially ZERO current flowing through the (preferably unique) ground reference and the circuit ground" should read something more like "..essentially ZERO current flowing through the (preferably unique) ground reference TO the circuit ground]

[Wombaticus]

LED biasing was patented in 1964
CATHODE BIAS CLAMP - Google Patent Search

The *really* sad thing about this all is that Gary almost certainly saw LED bias being used in old Navy equipment that he worked on, and perhaps assumed that nobody in the audio world knew about the idea... so why not claim the glory? As far as I can tell, it was indeed in Navy gear that the idea originated, at least you can find mention of LED biasing being used in Navy kit back in the early 60's. The funny thing about that patent, is that the assignors are both from the Navy. So really, Gary is mad that his scheme was unknowingly outed by the very people he, in turn, was trying lift the idea from. It's the only interpretation that is consistent with all of Gary's remarks. And also, pathetic.

[trem]

No! The notion that ground references are somehow a well from whence the electrons spring up is a horrible misconception that leads to all sorts of errors in grounding schemes! The key concept to bear in mind that is in a properly grounded amp, there will be essentially ZERO current flowing through the (preferably unique) ground reference and the circuit ground. For instance, early on I myself had the grand misconception that the safety ground was the ultimate source of electrons for the whole amp. Believe me, this leads to all kinds of crazy stuff.

In my admittedly crude way of thinking about these things, I prefer to imagine the power supply rails and the grounds as collectively forming a big racetrack (or nested racetracks) with the same electrons zipping around and around the same ovals over and over again, propelled by the EMF from the PT. In a properly grounded amp, the ground reference(s) are a complete sideshow. That the ground reference is NOT required to provide electrons, one need only consider that the whole circuit *could* be just left floating, and would still more-or-less work.

Well then I am lost again. Where do the electrons enter the filter caps that have their negative lead grounded? If it is through the negative lead, where do the electrons come from if not the chassis?
Thank You

[Chuck H]

Right. I was blathering. Of course electrons are from the cathodes. I meant to infer current. As in, "There is a lot of current through a power tube cathode resistor." That current is only available via the ground for that resistor and you certainly don't want how it's grounded to affect the preamp. Since part of this thread has been focused on the difference that was very clumsy of me.

I like the race track analogy.

[defaced]

Well then I am lost again. Where do the electrons enter the filter caps that have their negative lead grounded? If it is through the negative lead, where do the electrons come from if not the chassis?
Thank You

You're confusing voltage referencing with a conductor that carries current. They are not the same. Disconnect the safety ground on your amp and see if it still comes on. It will. So the chassis is not the source of the current, it is just a reference. The source of the current is the induced EMF in the transformer caused by the primary winding being energized by the wall outlet which is ultimately created by a spinning generator which is spinning at either 3000 or 3600 RPM, depends on your country, by either a gas or steam turbine. The safety ground is a wire sticking in the dirt outside of your house. Seriously. ground stake - Google Search

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You old guys should really turn the computer off and walk outside. This shit ain't that important.

[trem]

Right. I was blathering. Of course electrons are from the cathodes. I meant to infer current. As in, "There is a lot of current through a power tube cathode resistor." That current is only available via the ground for that resistor and you certainly don't want how it's grounded to affect the preamp. Since part of this thread has been focused on the difference that was very clumsy of me.

I like the race track analogy.

We must be talking about two different things. I realize the amp will work without the ground wire from the mains cord. Otherwise, all those amps with just a 2 wire cord would never have functioned.
What I am confused about is the source of electrons for the filter caps. The positive side are at, just to use a round number, 400 volts above ground. The negative side is at ground potential because it is connected to the chassis which is grounded via the safety ground, third wire of the power cord. My question is, if the chassis is not a source of electrons for the filter caps, what is? Where do the electrons enter the caps? In the schematic below, where do electrons enter and exit the filter caps?
Thank You
http://www.el34world.com/charts/Sche...a864_schem.pdf

[Wombaticus]

We must be talking about two different things. I realize the amp will work without the ground wire from the mains cord. Otherwise, all those amps with just a 2 wire cord would never have functioned.
What I am confused about is the source of electrons for the filter caps. The positive side are at, just to use a round number, 400 volts above ground. The negative side is at ground potential because it is connected to the chassis which is grounded via the safety ground, third wire of the power cord. My question is, if the chassis is not a source of electrons for the filter caps, what is? Where do the electrons enter the caps? In the schematic below, where do electrons enter and exit the filter caps?
Thank You
http://www.el34world.com/charts/Sche...b763_schem.pdf

I like defaced's answer as regards current flow. But to focus on your specific question about where the electrons "come from", the correct answer is that they were there all along. The lovely property of metals like copper is that makes them conductive is that they have outer electrons that tend not to associate strongly with a particular atom, but are instead relatively free to float about in the atomic lattice that comprises your wire. All that is required is an electromotive force to push them around for interesting things to happen. Remember, that a circuit, is well, just that, a circuit... it's pretty much a closed loop.

Capacitors are fun to think about. The first thing to realize is that the same electrons do NOT enter one end, and then leave through the other.... there is a non-conducting dialectric material separating the two ends. I've always found it more convenient to think about capacitors in terms of electrostatics rather than current, so I may get the following wrong -- perhaps an EE type will clarify any mistakes I make in what follows -- but forging ahead, it seems to me that an EMF must charge a capacitor by creating a local superabundance of electrons at the ground side, which is compensated for by a local underabundance of electrons on the positive side as they are effectively pushed out by repulsion across the dialectric, leaving an apparent positive charge. Anyway, an EMF is required to create this potential difference (voltage) you're talking about across the cap, but the net number of electrons in play in the circuit remains constant, so no additional electrons coming from some other source are needed.

Moreover, if we are talking about power supply caps that are smoothing an alternating current, then it seems like to me that electrons must be constantly entering and leaving BOTH ends (but never traveling through - otherwise capacitors would not block DC current!) depending on where in the cycle you are... Someone once told me a "waiting room" analogy for capacitors, where when the main hallway is crowded (ie current is flowing), charge carriers shuffle off to the capacitor to wait, and when the hallway becomes less crowded, they leave again (discharge) to keep the congestion in the hallway (the current) at a more-or-less constant level. Perhaps you can think of the two sides of the capacitor as being alternately occupied and emptied in a complementary fashion... kind of like a piston with a cylinder on both sides? I dunno, maybe someone else can do better with an analogy.

[trem]

OK, so if electrons are entering and leaving both ends of the cap, where do they come from and where do they go to? If the chassis, as you say, is not a source, how do electrons enter the negative lead of the cap?
Let me ask it this way. Suppose you are a instructor at a local college, and you are teaching a basic electronics class to a roomful of students that are just learning about this topic. If you were to explain to these students about electron flow in the filter caps of this schematic, what would you tell them.
1. Where do the electrons come from? (from the PT?)
2. How do they return to their origin? What is the path of travel of the electrons that charge the filter caps? Can a simple rode map be drawn that shows what happens to the electrons during the charging and discharging of these filter caps?
Thank You
http://www.el34world.com/charts/Sche...a864_schem.pdf

[Enzo]

Wombat, you are missing the point and are really talking about a different issue.

This is not about ground currents and grounding. And to say the electroncs were always there in the atoms, is misleading as well. You mention needing an electromotive force, well yes of course, and that is what pushes electrons on along. It is what allows the electrons in the common to move on into the rest of the circuit. And that is how the common is the source of the electrons.

The point is this, when your tube emits electrons from its cathode, they flow to its plate. More electrons must therefore come up through the cathode resistor to take their place. And where do they come from? The ground of the circuit. Call it the circuit common instead of ground to eliminate confusion between two meanings for the word ground. There certainly IS current in your circuit commons. In fact this whole discussion about direction of electron flow could just as easily be on a battery operated circuit not connected to earth at all. We often use the term ground to mean circuit common even when nothing is conected to the actual ground. We shouldn't abuse the term that way, but we do.

Now if I just connect a tube to ground, those electrons that had always been there would not start flowing to the plate. For that I need a power supply, and that supply must be connected to the plate AND to the common. SO while we just said the common is the source of the electrons into the cathode, it is also the case that the electrons in the common came from the power supply.

The common is a big pool of electrons only in the sense of the paths through the circuit. We are not suggesting the chassis is a bubbling pool of electrons just itching to spew all over. For current to flow, there must be a complete circuit. The old light bulb and battery lesson from 101 electricity. Since it is a circuit, it is a circle, so pick a spot, any spot, on the circuit as the start. My circuit is a tube and a battery, plus plate and cathode resistors. I pick the cathode to start at. It emits electrons which flow to the plate. Where did those electroncs come from? Through the cathode resistor. And how did they get to the cathode resistor? Through the common. And to the common? From the battery. The battery generates the potential, but it cannot send out electrons without replenishing them, and where do those come from? From the plate resistor. And how did the plate resistor wind up with them? From the plate. And the plate? it got them from the cathode. Circuit complete.

So the ground or common is the source of the electrons for the thing connected to it, that's all, not the source of all electrons for the world, just in a circuit stage, the electrons come from somewhere, and it winds up it is from the ground, rather than from the B+. And that is the basic question this entire thread is trying to answer. We are not suggesting the ground creates electrons, any more than the interstate creates cars, but also just like the interstate, when I see cars coming down the ramp, and someone asks where are those cars coming from, I can say, "from the interstate." Of course they had to enter the interstate at some other point, which would be analogy to our battery.

[guitarmike2107]

OK, so if electrons are entering and leaving both ends of the cap, where do they come from and where do they go to? If the chassis, as you say, is not a source, how do electrons enter the negative lead of the cap?
Let me ask it this way. Suppose you are a instructor at a local college, and you are teaching a basic electronics class to a roomful of students that are just learning about this topic. If you were to explain to these students about electron flow in the filter caps of this schematic, what would you tell them.
1. Where do the electrons come from? (from the PT?)
2. How do they return to their origin? What is the path of travel of the electrons that charge the filter caps? Can a simple rode map be drawn that shows what happens to the electrons during the charging and discharging of these filter caps?
Thank You
http://www.el34world.com/charts/Sche...a864_schem.pdf

That grounding diagram uses the chassis as part of the circuit instead of using wires to connect up the circuit.
Obviously it can be done like that because the chassis is conductive, and this is very common in vintage amps.
And obviously if the chassis is used as part of the circuit there will be currents in it, but I wonder how many people here use this type of arrangement, I don’t, the chassis is a housing and a shield not a component for completing the circuit.

You can build an entire amp circuit out of the chassis and it will still work, it will probably buzz more but it will still work.

Have a look at Merlins article on grounding
http://valvewizard2.webs.com/Grounding.pdf

[Steve Conner]

Broadly speaking, that is right. The wires of the circuit, any metal part of it, are all chock full of loose electrons, ready to conduct current. But the electrons won't go anywhere of their own accord, they need a potential difference ("voltage") to shove them.

You can think of the PT secondary and rectifier as a kind of "pump" that creates a surplus of them in the ground rail and a corresponding deficit in the B+. They find their way back up to B+ through the amp circuit and get pumped back round over and over again. The amount of electrons that flow in this way is a tiny fraction of the ones actually available in the metal for conduction.

Many people like the mental analogy between electric circuits and water in hoses, pipes, tanks and so on. A capacitor is like one of those big water towers, a resistor is like a tiny hole that the water has to squeeze through, and a tube is like, well, a valve. I don't know what plumbing part an inductor corresponds to. Maybe a big long pipe that the water can build up momentum in.

The analogy works smoothest with conventional current (the "positive particles"), then voltage is directly analogous to height of your plumbing above ground. That is why it's good to draw schematics with the potential gradient going up the page, you can visualize that (non-existent) "conventional current" cascading down from top to bottom.

It can get you quite far, but it starts to crumble horribly when you try to think about induction, electromagnetic fields, radiation and so on. An antenna is absolutely nothing like a fire hose or garden sprinkler. This can cause a fair amount of mental pain, and the only cure is to stare at Maxwell's equations for a long time until you get what is really happening.

[txstrat]

Excuse me guys for getting off topic:

Enzo I just noticed your ski jumper avatar and couldn't help myself but laughing out loud. Great. Thank you for making my day.

But to get to topic again. This is quite a great thread. Very interesting to view things from different sides.

[trem]

Broadly speaking, that is right. The wires of the circuit, any metal part of it, are all chock full of loose electrons, ready to conduct current. But the electrons won't go anywhere of their own accord, they need a potential difference ("voltage") to shove them.

You can think of the PT secondary and rectifier as a kind of "pump" that creates a surplus of them in the ground rail and a corresponding deficit in the B+. They find their way back up to B+ through the amp circuit and get pumped back round over and over again. The amount of electrons that flow in this way is a tiny fraction of the ones actually available in the metal for conduction.

Many people like the mental analogy between electric circuits and water in hoses, pipes, tanks and so on. A capacitor is like one of those big water towers, a resistor is like a tiny hole that the water has to squeeze through, and a tube is like, well, a valve. I don't know what plumbing part an inductor corresponds to. Maybe a big long pipe that the water can build up momentum in.

The analogy works smoothest with conventional current (the "positive particles"), then voltage is directly analogous to height of your plumbing above ground. That is why it's good to draw schematics with the potential gradient going up the page, you can visualize that (non-existent) "conventional current" cascading down from top to bottom.

It can get you quite far, but it starts to crumble horribly when you try to think about induction, electromagnetic fields, radiation and so on. An antenna is absolutely nothing like a fire hose or garden sprinkler. This can cause a fair amount of mental pain, and the only cure is to stare at Maxwell's equations for a long time until you get what is really happening.

Thank you and the man that posted before you....
In simple terms, can somebody tell me the electron path for the filter caps in this schematic? What I see is the PT secondary has a CT to the chassis. From there the electrons flow (during each negative to positive cycle of that half of the PT secondary) to the negative side of the filter caps, out the positive side of the caps (during charge and discharge), and from the "B+" they rail return to the PT secondary via the stand by switch and rectifier diodes.
Is that "basically" where the electrons come from and go to?
Thank You
http://www.el34world.com/charts/Sche...a864_schem.pdf

[Steve Conner]

No. They do not flow through the filter caps. Those are just a holding tank, if you like. Imagine buckets full of electrons being dumped in to the filter capacitors 120 times per second, and a smooth flow comes out to operate the circuit.

The circuit for electron flow is: Out of the PT center tap, piling up in the filter capacitors for a while, then travelling on through the tubes to eventually get to the B+ rail, where they get sucked towards the filter caps again, and pile up on the positive side for a bit, waiting for their turn to get through the rectifier.

Around the peak of every half-cycle of the line, a bunch of them shoot through the rectifier tube, through one or other half of the PT secondary, and then back out of the center tap for another lap.