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Post by ourclarioncall on Dec 9, 2019 20:12:27 GMT -5
Ground ? Earth ?
So what actually is grounding ? Does electricity actually go into the ground ? Do electrons go into the dirt ? Rocks ? Worms ? Where do they go?
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Post by newey on Dec 9, 2019 22:49:59 GMT -5
If you're Murrican.  If you're Commonwealth-ish. After all, the Sun never sets on . . . Earth, as a whole anyway. It's always Happy Hour somewhere.  Yes, if a circuit has been made. Trying to conceptualize it in this way will quickly get misleading and counterproductive. The electrons were already there, in the dirt, worms,etc. They're just getting reshuffled a bit. As was pointed out earlier(IIRC), ground can be thought of as a reference point, a plane from which circuits arise. Yes, it is referenced to the physical soil of our planet. It has to be referenced to something . . . I believe it was ashcatlt who has pointed out that, technically, every point in the universe is electrically connected to every other point- it is merely a question of having enough juice to overcome the resistance. . . |
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Post by ourclarioncall on Dec 9, 2019 23:05:30 GMT -5
If you're Murrican. If you're Commonwealth-ish. After all, the Sun never sets on . . . Earth, as a whole anyway. It's always Happy Hour somewhere. Yes, if a circuit has been made. Trying to conceptualize it in this way will quickly get misleading and counterproductive. The electrons were already there, in the dirt, worms,etc. They're just getting reshuffled a bit. As was pointed out earlier(IIRC), ground can be thought of as a reference point, a plane from which circuits arise. Yes, it is referenced to the physical soil of our planet. It has to be referenced to something . . . I believe it was ashcatlt who has pointed out that, technically, every point in the universe is electrically connected to every other point- it is merely a question of having enough juice to overcome the resistance. . . Mind blown 😆 But yeah , it’s makes sense. Kind of. |
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Post by ashcatlt on Dec 10, 2019 18:48:52 GMT -5
All voltage is relative. Ground is whatever point in your circuit that you choose to be the reference point against which all others are measured. It doesn’t have to have anything to do with the actual earth.
Edit - Did I ever tell you about the theory that there was some planet-sized object that ejected from Jupiter, careened across the solar system, and came pretty close to the earth? From what I read it had a large enough charge difference from us that there was a big old arc that may have been the column of fire which destroyed pharoa’s army in the biblical story.
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Post by ourclarioncall on Dec 10, 2019 20:26:43 GMT -5
All voltage is relative. Ground is whatever point in your circuit that you choose to be the reference point against which all others are measured. It doesn’t have to have anything to do with the actual earth. Edit - Did I ever tell you about the theory that there was some planet-sized object that ejected from Jupiter, careened across the solar system, and came pretty close to the earth? From what I read it had a large enough charge difference from us that there was a big old arc that may have been the column of fire which destroyed pharoa’s army in the biblical story. What I don’t have a clue about when it come to electricity , I make up for in bible knowledge 🙂 (I’m a preacher ) Have never heard the above theory , but do know the account of Pharoh well. |
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Post by blademaster2 on Dec 11, 2019 10:01:20 GMT -5
All voltage is relative. Ground is whatever point in your circuit that you choose to be the reference point against which all others are measured. It doesn’t have to have anything to do with the actual earth. Edit - Did I ever tell you about the theory that there was some planet-sized object that ejected from Jupiter, careened across the solar system, and came pretty close to the earth? From what I read it had a large enough charge difference from us that there was a big old arc that may have been the column of fire which destroyed pharoa’s army in the biblical story. True. For systems on Earth, ground is loosely used to refer to the common reference point of voltage to which all current returns, and sometimes it is actually connected to the Earth (as in buildings, homes, ...). For shielding noise, the Earth is good also but if a voltage is measured differentially (looking only at the difference between to connections, which applies to a battery-powered amplifier) then it need not be. Guitar amplifiers are usually grounded to Earth but only if a third prong exists on the amplifier. If not then it is only looking at the guitar signal differentially and the shield is simply the common reference point. In spacecraft, of course, the spacecraft structure is usually defined as "ground" and there is no connection to the Earth (duh). In space a charge can build up to be very large if a part of a spacecraft is not connected ('galvanically isolated') to the spacecraft ground. When it is big enough it can arc, just like lightning. |
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Post by ashcatlt on Dec 11, 2019 19:52:43 GMT -5
Have never heard the above theory , but do know the account of Pharoh well. No, and it kind of didn’t occur to me that I was crossing that politics/religion line. Sorry if it offends anybody. |
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Post by ourclarioncall on Dec 11, 2019 20:09:37 GMT -5
Have never heard the above theory , but do know the account of Pharoh well. No, and it kind of didn’t occur to me that I was crossing that politics/religion line. Sorry if it offends anybody. Oh don’t worry my friend , you haven’t offended me in the slightest 🙂 I love talking about bible stuff. If your interested , the account can be found in the book of exodus . What the theory was referring to was a pillar of cloud by day and a pillar of fire by night. Pharoh ended up being drowned in the Red Sea along with his army. 👍 |
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Post by thetragichero on Dec 11, 2019 20:27:44 GMT -5
Guitar amplifiers are usually grounded to Earth but only if a third prong exists on the amplifier. If not then it is only looking at the guitar signal differentially and the shield is simply the common reference point. this is not true as, at least in the us, the neutral wire is tied to ground at the point where the power enters the building. there have been all sorts of fonky treatment of ac ground in amplifiers, including polarity switches which solve one problem (the high chance that the bar you're playing in was wired incorrectly by a patron willing to work for free booze) by causing another (the possibility of connecting the chassis to mains voltage) i would imagine all amps with a power transformer of some type would have to have a well-defined dc ground, no? that may or may not be the same as ac ground. many of the solid state amps I've dealt with have bipolar supplies so dc ground is halfway between (in theory) the negative and positive power rails |
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Post by sumgai on Dec 11, 2019 22:26:50 GMT -5
Guitar amplifiers are usually grounded to Earth but only if a third prong exists on the amplifier. If not then it is only looking at the guitar signal differentially and the shield is simply the common reference point. this is not true as, at least in the us, the neutral wire is tied to ground at the point where the power enters the building. there have been all sorts of fonky treatment of ac ground in amplifiers, including polarity switches which solve one problem (the high chance that the bar you're playing in was wired incorrectly by a patron willing to work for free booze) by causing another (the possibility of connecting the chassis to mains voltage) i would imagine all amps with a power transformer of some type would have to have a well-defined dc ground, no? that may or may not be the same as ac ground. many of the solid state amps I've dealt with have bipolar supplies so dc ground is halfway between (in theory) the negative and positive power rails In actuallity, blademaster2 is correct, even though he takes an unfortunate shortcut, leaving out an important word, like so: ... are grounded directly to Earth but only if...
In all cases, since the time of the first amplifier (and not just for guitars, I mean all amps period), the chassis was connected to "ground" as in it was connected to Earth. Why? Because this was the way that radios worked. Recall that you can make a very simple "razor blade radio", just like the G.I.s of WWII fame, but that's about the only kind of radio lash-up that doesn't need a wire going to ground. (It was also called a 'crystal radio' among the hobbyists who could afford more than just a razor blade.)
In the beginning, there were batteries (Leyden jars) powering the nascent radios and such. Not much chance of AC shock there. But if we skip forward a decade or two, we see that Westinghouse has won the "power wars", and AC is the name of the game. Now we have some safety issues, but they aren't apparent to the average householder and family.... yet. But in the meantime, because radio waves travel between the atmosphere and the Earth (the ground itself), we maintain the need for grounding all such electrical devices. It soon develops that doing so provides a convenient reference point, against which we can measure things, and we can be assured that the same measurements will give the same results no matter where on the globe (on land, of course) we might be situated.
This is why, before the advent of the third wire, two wires were used to bring power to a building. But immediately, one wire, designated as Neutral, was connected to the Earth ground. Againg, why? And also again, because of commonality - being able to run one wire instead of two, and having the "other" wire being brought around for us via the nice "feature" of having lots of metal nearby, that was pretty nifty in those days. But your final question, why use the Earth for a power carrier?, well that's obvious - the Earth ground is a massive resistance to DC and low frequencies. A second wire is needed to supply power over long runs, but not for short distances, say several feet.
Please don't get me started on the alleged safety of the third wire, I'll wear down the markings on my keyboard the rest of the way to invisibility if I have to provide that particular rant. 
HTH
sumgai
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Post by b4nj0 on Dec 12, 2019 3:18:28 GMT -5
It is sometimes held that a car battery is in essence little more than an enormous capacitor. Well anything with opposing polarities held separate satisfies that criterion and low leakage capacitors are indeed used for short term memory retention, but with all that in mind, I always thought of the Leyden Jar (or more simply the "Jar") as an earlier (if not the original) measure of capacitance? I shall revise that impression if the Jar was also a unit of electromotive force. This demonstrates to me that I'm not immune from holding unfounded ideas! Step forward Mr. Leyden!
e&oe ...
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Post by sumgai on Dec 12, 2019 12:37:15 GMT -5
It is sometimes held that a car battery is in essence little more than an enormous capacitor. Well anything with opposing polarities held separate satisfies that criterion and low leakage capacitors are indeed used for short term memory retention, but with all that in mind, I always thought of the Leyden Jar (or more simply the "Jar") as an earlier (if not the original) measure of capacitance? I shall revise that impression if the Jar was also a unit of electromotive force. This demonstrates to me that I'm not immune from holding unfounded ideas! Step forward Mr. Leyden! e&oe ...In point of fact, where the capacitor is nothing more than a "holder" of a charge, a battery (or more properly, a cell) actually does a chemical conversion of energy - it does not "just hold" an electrical charge in chemical form. Although if one really wants to get into it, the Laws of Energy Conservation could be invoked to mean that all energy can be converted to some other form, meaning that a "holding" action is really in play. As I learned it, way back when, a cap can only discharge what was put into in the first place, whereas a battery can be discharged quite often, and wonder of wonders, even without a direct recharge, it can actually deliver more energy, if it is given some time to "recover".
The obligatory car analogy: Let us assume that you use the car's battery to start the car every morning. It's near freezing outside, so the engine doesn't start immediately; it takes several seconds of turning over, and thus the battery is working pretty hard. If you run the motor for just 1 minute, that's not enough time for the alternator to send a charge back into the battery to completely replace what was used to start the motor. Yet, during the day, the battery is at rest, and when the next morning comes, it can do the job again. And again, and so on.
Start by measuring the initial amount of power it took to bring the battery to full charge, this will be your base line to measure against. Now, measure the amount of charge used by the starter each morning. Keep doing that every day, for a month. Totaling up those numbers will surprise you - said total is much greater than your initial power reading. Why? Because the chemical reaction can regain its potential simply by resting.
Now, that's a short-and-sweet story, and it breaks down under a deeper analysis. But the real point of the analgy is that if you compare that activity to a capacitor's capabilities, you'll see a marked difference. As in, the cap can't recuperate simply by 'resting'. In fact, for every electron discharged from the cap, said electron is gone. If you want another electron to be ready for discharging, the you're going to have to charge the cap with one, before the next discharge event.
In short, a cap does not do any 'energy conversion', it simply stores a charge of electrons on one of its plates, until a circuit is completed and the charge is dissipated into some other component/load.
Fun fact: In the very beginning, the pioneers called a capacitor an "accumulator". 'Struth!
Further fun fact: For some time after "accumulator" fell out of favor, the capacitor was called a "condensor" (or very occasionally, spelled as 'condenser'). Once in awhile, you still run across this nomenclature on old schematics.
HTH
sumgai
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Post by ourclarioncall on Dec 14, 2019 9:20:10 GMT -5
I really enjoyed reading the last few comments
Didn’t understand a word of it but it was interesting 😄
Complicated stuff inspires me that there is more to learn
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Post by blademaster2 on Dec 20, 2019 15:19:22 GMT -5
this is not true as, at least in the us, the neutral wire is tied to ground at the point where the power enters the building. there have been all sorts of fonky treatment of ac ground in amplifiers, including polarity switches which solve one problem (the high chance that the bar you're playing in was wired incorrectly by a patron willing to work for free booze) by causing another (the possibility of connecting the chassis to mains voltage) i would imagine all amps with a power transformer of some type would have to have a well-defined dc ground, no? that may or may not be the same as ac ground. many of the solid state amps I've dealt with have bipolar supplies so dc ground is halfway between (in theory) the negative and positive power rails In actuallity, blademaster2 is correct, even though he takes an unfortunate shortcut, leaving out an important word, like so: ... are grounded directly to Earth but only if...
In all cases, since the time of the first amplifier (and not just for guitars, I mean all amps period), the chassis was connected to "ground" as in it was connected to Earth. Why? Because this was the way that radios worked. Recall that you can make a very simple "razor blade radio", just like the G.I.s of WWII fame, but that's about the only kind of radio lash-up that doesn't need a wire going to ground. (It was also called a 'crystal radio' among the hobbyists who could afford more than just a razor blade.)
In the beginning, there were batteries (Leyden jars) powering the nascent radios and such. Not much chance of AC shock there. But if we skip forward a decade or two, we see that Westinghouse has won the "power wars", and AC is the name of the game. Now we have some safety issues, but they aren't apparent to the average householder and family.... yet. But in the meantime, because radio waves travel between the atmosphere and the Earth (the ground itself), we maintain the need for grounding all such electrical devices. It soon develops that doing so provides a convenient reference point, against which we can measure things, and we can be assured that the same measurements will give the same results no matter where on the globe (on land, of course) we might be situated.
This is why, before the advent of the third wire, two wires were used to bring power to a building. But immediately, one wire, designated as Neutral, was connected to the Earth ground. Againg, why? And also again, because of commonality - being able to run one wire instead of two, and having the "other" wire being brought around for us via the nice "feature" of having lots of metal nearby, that was pretty nifty in those days. But your final question, why use the Earth for a power carrier?, well that's obvious - the Earth ground is a massive resistance to DC and low frequencies. A second wire is needed to supply power over long runs, but not for short distances, say several feet.
Please don't get me started on the alleged safety of the third wire, I'll wear down the markings on my keyboard the rest of the way to invisibility if I have to provide that particular rant.
HTH
sumgai
Yes, I did ignore the neutral-to-ground connection - mostly because the voltage on it is highly variable depending on the noise it carries from other loads and the current being drawn by other loads on the same chain of connections. So in that sense it is *not* ground despite the wired connection it has to ground. If *zero*current is flowing anywhere, then the neutral is identical to ground (Earth). In all other cases there is something of a voltage and signal on it relative to ground. The actual third-prong ground is supposed to have no current flowing at all times and therefore sits at the zero-volt Earth voltage, which is why it is safest to connect the exposed external metal of appliances to it: there will then be no voltage difference between any two appliances and/or plumbing in the home. Neutral lines cannot make that guarantee, and even if the voltage is at times rather low on the neutral line it has a very low impedance and therefore a lot of current can flow from it to the actual ground (Earth). On that basis, I do recognize the safety of the third wire in a correctly-wired home. If sumgai has a different take on this then I am interested to hear it (rant or otherwise). :-) |
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Post by blademaster2 on Dec 20, 2019 15:29:18 GMT -5
It is sometimes held that a car battery is in essence little more than an enormous capacitor. Well anything with opposing polarities held separate satisfies that criterion and low leakage capacitors are indeed used for short term memory retention, but with all that in mind, I always thought of the Leyden Jar (or more simply the "Jar") as an earlier (if not the original) measure of capacitance? I shall revise that impression if the Jar was also a unit of electromotive force. This demonstrates to me that I'm not immune from holding unfounded ideas! Step forward Mr. Leyden! e&oe ...In point of fact, where the capacitor is nothing more than a "holder" of a charge, a battery (or more properly, a cell) actually does a chemical conversion of energy - it does not "just hold" an electrical charge in chemical form. Although if one really wants to get into it, the Laws of Energy Conservation could be invoked to mean that all energy can be converted to some other form, meaning that a "holding" action is really in play. As I learned it, way back when, a cap can only discharge what was put into in the first place, whereas a battery can be discharged quite often, and wonder of wonders, even without a direct recharge, it can actually deliver more energy, if it is given some time to "recover".
The obligatory car analogy: Let us assume that you use the car's battery to start the car every morning. It's near freezing outside, so the engine doesn't start immediately; it takes several seconds of turning over, and thus the battery is working pretty hard. If you run the motor for just 1 minute, that's not enough time for the alternator to send a charge back into the battery to completely replace what was used to start the motor. Yet, during the day, the battery is at rest, and when the next morning comes, it can do the job again. And again, and so on.
Start by measuring the initial amount of power it took to bring the battery to full charge, this will be your base line to measure against. Now, measure the amount of charge used by the starter each morning. Keep doing that every day, for a month. Totaling up those numbers will surprise you - said total is much greater than your initial power reading. Why? Because the chemical reaction can regain its potential simply by resting.
Now, that's a short-and-sweet story, and it breaks down under a deeper analysis. But the real point of the analgy is that if you compare that activity to a capacitor's capabilities, you'll see a marked difference. As in, the cap can't recuperate simply by 'resting'. In fact, for every electron discharged from the cap, said electron is gone. If you want another electron to be ready for discharging, the you're going to have to charge the cap with one, before the next discharge event.
In short, a cap does not do any 'energy conversion', it simply stores a charge of electrons on one of its plates, until a circuit is completed and the charge is dissipated into some other component/load.
Fun fact: In the very beginning, the pioneers called a capacitor an "accumulator". 'Struth!
Further fun fact: For some time after "accumulator" fell out of favor, the capacitor was called a "condensor" (or very occasionally, spelled as 'condenser'). Once in awhile, you still run across this nomenclature on old schematics.
HTH
sumgai
.... like 'condenser' microphones, which essentially works by charging up a capacitor (a.k.a condenser) that will change its capacitance value as the plates move back and forth with the sound waves hitting it. The signal coming from it is then essentially the displacement current from the biased capacitor at a fixed voltage as its capacitance is modulated. I bet nobody really wanted to hear that in this forum, but there it is. |
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Post by sumgai on Dec 20, 2019 20:03:53 GMT -5
...... On that basis, I do recognize the safety of the third wire in a correctly-wired home. If sumgai has a different take on this then I am interested to hear it (rant or otherwise). :-) Nope, no rant necessary. Your explanation is clear and concise, at least to me. I accept that what you've said is true, but it did go into a lot of detail pretty far beyond the level we normally achieve here in The NutzHouse.  You've noticed over the years that I can become quite pedantic, but I most often try to keep it down to a dull roar.  My rant would be pointed more toward the inability of an average person to understand that things can be simple, but doing so often invites risk. In my opinion, adding complexity in the name of "protecting the user" is only staving off the inevitable - the user still manages to find a way to chlorinate the gene pool.... just took him a bit more effort, but like they say: You can build a fool-proof product, but someone will just build a better fool. sumgai |
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Post by sumgai on Dec 20, 2019 20:06:12 GMT -5
.... like 'condenser' microphones, which essentially works by charging up a capacitor (a.k.a condenser) that will change its capacitance value as the plates move back and forth with the sound waves hitting it. The signal coming from it is then essentially the displacement current from the biased capacitor at a fixed voltage as its capacitance is modulated. I bet nobody really wanted to hear that in this forum, but there it is. Nice one! I completely spaced on that as an example, thanks for the uptick. sumgai |
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You've noticed over the years that I can become quite pedantic, but I most often try to keep it down to a dull roar. 