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Author Topic: Silly question about voltage and current  (Read 49293 times)

dieter

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Silly question about voltage and current
« on: February 24, 2014, 08:05:51 PM »
I have a question: Do the voltage and the current for a cetrain load have to come from the same source?


Or could I, example given, use two independent sources like photopholtaic and wind or whatever, then go out of phase with each one by -90 resp. +90 degrees with a cap and a coil, then ac- sync this so in none of them is actally both (v+a) present, then simply but these together , maybe trough some diodes, to get a complete, working source of V+A ?

TinselKoala

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Re: Silly question about voltage and current
« Reply #1 on: February 24, 2014, 08:40:31 PM »
I have a question: Do the voltage and the current for a cetrain load have to come from the same source?


Or could I, example given, use two independent sources like photopholtaic and wind or whatever, then go out of phase with each one by -90 resp. +90 degrees with a cap and a coil, then ac- sync this so in none of them is actally both (v+a) present, then simply but these together , maybe trough some diodes, to get a complete, working source of V+A ?

Huh? Voltage is the pressure that pushes current through a load. It is impossible to separate voltage and current. Even the highest impedance voltmeter there is (electrostatic voltmeter) needs some tiny current put into it by the voltage it is measuring. And even the slightest possible current needs some tiny voltage difference between the source and sink in order to flow.

Now.... you can certainly do weird things like putting sources in series. For example, my old RM503 oscilloscope has a CRT with a 12 volt filament, that draws a few hundred mA when operating. BUT.... this filament is raised to 3000 volts over the system's ground level, because it plays a role in the emission of the electron beam in the CRT. This is done by feeding the filament with a winding from the main power transformer, biasing it from the scope's HV section and limiting the voltage _difference_ across the filament so that only the small current flows, not the current that would happen (very briefly!) if the filament was hooked directly across the 3000 volt source. The scope didn't work when I first got it, it kept blowing fuses and I finally figured out it was because of insulation breakdown within the main (expensive and complicated) power transformer: the 3000 V biased winding was shorting to another winding within the transformer somehow. How to fix this without replacing the transformer (impossible to do anyway). So I got a good quality 12 volt transformer from Radio Shack, powered its 120 v primary from the mains, and let the secondary be elevated to the 3000 volt level by the scope's voltage multiplier, and I drove the filament from that. It works 100 percent fine now. So... in this sense yes, the 3000 volt elevation is provided from the HV section of the scope, and the actual current through the filament is provided by the 12 volt winding on the RadioShack transformer. Since the RS transformer's secondary is not inside the main transformer the original short is eliminated, and the insulation in the new transformer is good enough to keep the 3000 volt bias elevation of the secondary from leaking through to the primary and causing the same problem as before. The filament current is running on the voltage difference between 3012 volts and 3000 volts and this current comes from a different source than the 3000 volt elevation.

There--- are you completely confused even more now? Don't feel too badly, it took me quite some time to track down this problem and understand it to the point where I could repair the scope. It's a classic antique though and has some unique features, so I really was motivated to fix it, and I learned a lot while doing it.

dieter

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Re: Silly question about voltage and current
« Reply #2 on: February 24, 2014, 09:25:17 PM »
So. that's a yes?
actually, isn't voltage and current sperated when they are out of phase? As in a coil the voltage is established earlier than the current and in a cap later, there is a moment in the ac cycle where both, the coil and the cap contain only v or a (?)


What if we tap this very moment only, by switching? Both is there, v + a, although maybe not as a perfect sinus wave.

TinselKoala

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Re: Silly question about voltage and current
« Reply #3 on: February 24, 2014, 09:58:14 PM »
So. that's a yes?
actually, isn't voltage and current sperated when they are out of phase? As in a coil the voltage is established earlier than the current and in a cap later, there is a moment in the ac cycle where both, the coil and the cap contain only v or a (?)


What if we tap this very moment only, by switching? Both is there, v + a, although maybe not as a perfect sinus wave.

Well, not exactly. Yes, you can certainly "have" a voltage without current, as in a disconnected battery.... but any _measurement_ you make of the voltage will require a tiny current at least to flow through or into your instrument. This also means that any _use_ of the power requires current to flow. The phase shift in AC power feeding a reactive load means that the overall power is split into Real or True power (that powers or is dissipated in a load) and Reactive Power which isn't dissipated in the load,  and Apparent Power which is the total power. The distribution of the input into these parts is dependent on the phase angle.
http://www.allaboutcircuits.com/vol_2/chpt_11/2.html

Turbo

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Re: Silly question about voltage and current
« Reply #4 on: February 25, 2014, 07:00:04 AM »
That is of cource the pre historic view on electricity and most of the old lad's think of it that way.
But in the real world, there is no voltage nor is there current flow and these elements only show up when the time component is taken into the equation.
What it means is that if you were to freeze time, all voltage would dissapear, and all current would stop flowing.
If you look at for example the pre historic equation, Power(in Watts) = Voltage(in Volts) x Current (in Amps) you can already see that there is no mention of the time component, and that therefore this equation is pre historic and incomplete.
Because from this equation, you can not tell if the total sum is per second, minute,hour,day or whatever and if you need to build a perfect model in a perfect world where time does not exist, you will run into problems with this.
In the classical sense it would be Joule per second, but when you are unable to measure the time component, you will run into problems with this.
I think it is interesting to see that the only place where this is really important, is in the area most people on this board are intrested in, and for the rest of the world this would not make any difference as long as the light comes on when they flip the switch...
But only so few understand this and only so few know what it is really about it all depends on your point of view so, from which point you are looking and measuring, to understand this you need to develop a complete shift in perspective because the 'normal' view is too limited to be able to explain and understand it.


 It is impossible to separate voltage and current.


Only if you think it is.

MileHigh

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Re: Silly question about voltage and current
« Reply #5 on: February 25, 2014, 07:29:02 AM »
It's kind of funny that you go into a treatise about time because all serious electronics analysis is based on time.  In fact, often the analysis is based on analyzing what happens during an infinitely thin slice of time.

So a huge chunk of science is built around understanding what happens during an infinitely thin slice of time or with an infinitely thin wedge of a circle or with an infinitely thin slice of solid and so on.  It dates back to the Renaissance.  For example, how does current flow through a conductor?  You cut up the conductor into infinitely small cubes to find out.

MileHigh

TinselKoala

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Re: Silly question about voltage and current
« Reply #6 on: February 25, 2014, 08:00:51 AM »
That is of cource the pre historic view on electricity and most of the old lad's think of it that way.
But in the real world, there is no voltage nor is there current flow and these elements only show up when the time component is taken into the equation.
I guess you haven't heard of static electricity, and you probably think that batteries don't have any voltage in them until they are connected to something. Your refrigerator light probably stays on even with the door closed, too.
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What it means is that if you were to freeze time, all voltage would dissapear, and all current would stop flowing.
Sure, and if pigs had wings and a takeoff clearance from the tower, they could fly. BUT THEY DON'T, and YOU CANNOT FREEZE TIME.
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If you look at for example the pre historic equation, Power(in Watts) = Voltage(in Volts) x Current (in Amps) you can already see that there is no mention of the time component, and that therefore this equation is pre historic and incomplete.
Oh come on, stop right there. What is the definition of a Watt? Answer the question. What is the definition of an Ampere? Answer the question. Now... does time enter into the "prehistoric equation" or not?
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Because from this equation, you can not tell if the total sum is per second, minute,hour,day or whatever and if you need to build a perfect model in a perfect world where time does not exist, you will run into problems with this.
In the classical sense it would be Joule per second, but when you are unable to measure the time component, you will run into problems with this.
What is an oscilloscope? What is a frequency counter? How does a receiver like your cellphone know to tune into a GigaHertz frequency? How does GPS work? Just who is unable to measure a time component, I wonder. I can measure time down to the single nanosecond with my "garage sale" equipment. I'm sorry that you cannot, and I'm sorry that I won't be able to teach you how to do it, since you already know you can't.
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I think it is interesting to see that the only place where this is really important, is in the area most people on this board are intrested in, and for the rest of the world this would not make any difference as long as the light comes on when they flip the switch...
But only so few understand this and only so few know what it is really about it all depends on your point of view so, from which point you are looking and measuring, to understand this you need to develop a complete shift in perspective because the 'normal' view is too limited to be able to explain and understand it.

Only if you think it is.

I'll bet money that you would have been unable to repair my RM503 scope, with the depth of your understanding.

Turbo

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Re: Silly question about voltage and current
« Reply #7 on: February 25, 2014, 11:25:34 AM »
See you are talking only from the physical layer.
There is a problem with your understanding.

You just don't get what i am trying to say becuse of your limited mindeset.
I am sorry for you.

Maybe you read it again so you understand you are in a place where time itself does not exist instead of dragging oscilloscopes and frequency counters to this place....
Becuse they are useless if there is no time then they will read 0 and i think you are a fool for not understanding that.
I was clear about what i ment.

MarkE

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Re: Silly question about voltage and current
« Reply #8 on: February 25, 2014, 11:38:28 AM »
See you are talking only from the physical layer.
There is a problem with your understanding.

You just don't get what i am trying to say becuse of your limited mindeset.
I am sorry for you.

Maybe you read it again so you understand you are in a place where time itself does not exist instead of dragging oscilloscopes and frequency counters to this place....
Becuse they are useless if there is no time then they will read 0 and i think you are a fool for not understanding that.
I was clear about what i ment.
Improved concepts need to account for behaviors explained by the concepts that they would replace.  Before anyone can consider that you may have a superior idea you need to reconcile the fact that you assert incorrectly that:  Power, the time derivative of energy does not involve time, or that current, the time derivative of charge crossing a point does not involve time.  If your ideas depend on these false assertions, then your ideas fail to explain observations covered by existing models and therefore fail.

Turbo

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Re: Silly question about voltage and current
« Reply #9 on: February 25, 2014, 11:59:33 AM »
You have a limited mindset also you can not grasp the concept because you are looking at a 4 dimensional picture in 3 dimensional space and as a result you can never solve that equation.

let me make one thing clear.

ELECTRIC ENERGY FLOWS FROM A PLACE WHERE NO TIME EXISTS TO A PLACE WHERE TIME DOES EXIST.

YOU are in the place where time flows, with all your meters scopes frequency conter and all the other bullshit equipment that KNOWS how LONG A SECOND IS.
But taker all your measuring devices into that OTHER dimension and they will FAIL to work because A SECOND ITSELF does not EXIST there so the MEASURING DEVICE CAN NOT MEASURE ANYTHING.

I know it's beyond your scope of imagination, yet
Let me put it this way, you need to get thinking OUTSIDE the physical layer you are currently in...if you existed in the other realm, things would heve been easier for you.
If time moves at lightspeed and electricity moves at lightspeed and they move in the same direction then YOU MIGHT figure out some time.

So yea
I am not going to discuss this any further you all hang on to you pre historic models and go fuel up you car.
It seems you have to die first in order to gain this understanding.

MarkE

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Re: Silly question about voltage and current
« Reply #10 on: February 25, 2014, 12:03:52 PM »
You have a limited mindset also you can not grasp the concept because you are looking at a 4 dimensional picture in 3 dimensional space and as a result you can never solve that equation.

let me make one thing clear.

ELECTRIC ENERGY FLOWS FROM A PLACE WHERE NO TIME EXISTS TO A PLACE WHERE TIME DOES EXIST.

YOU are in the place where time flows, with all your meters scopes frequency conter and all the other bullshit equipment that KNOWS how LONG A SECOND IS.
But taker all your measuring devices into that OTHER dimension and they will FAIL to work because A SECOND ITSELF does not EXIST there so the MEASURING DEVICE CAN NOT MEASURE ANYTHING.

I know it's beyond your scope of imagination, yet
Let me put it this way, you need to get thinking OUTSIDE the physical layer you are currently in.
If time moves at lightspeed and electricity moves at lightspeed and they move in the same direction then YOU MIGHT figure out some time.

So yea
I am not going to discuss this any further you all hang on to you pre historic models and go fuel up you car.
It seems you have to die first in order to gain this understanding.
You make claims that existing observations contradict.  For example E/M waves do not move at a constant speed.  You are free to howl at the moon as you will.

Turbo

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Re: Silly question about voltage and current
« Reply #11 on: February 25, 2014, 12:06:57 PM »
I howl:

You did not read what i wrote you just replied to it.

You do not know what a EM wave really is.
If there is not time how can it vary in speed?
You do not know what electricity is.

Fin.

Tseak

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Re: Silly question about voltage and current
« Reply #12 on: February 25, 2014, 12:37:34 PM »
Quote
So yea
I am not going to discuss this any further

Please keep your promise.

MarkE

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Re: Silly question about voltage and current
« Reply #13 on: February 25, 2014, 01:23:45 PM »
I howl:

You did not read what i wrote you just replied to it.

You do not know what a EM wave really is.
If there is not time how can it vary in speed?
You do not know what electricity is.

Fin.
Set up an experiment and show that your ideas make more accurate predictions than conventional theory.  Show that your ideas make predictions that are at least as accurate as conventional theory for at least common circumstances.

TinselKoala

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Re: Silly question about voltage and current
« Reply #14 on: February 25, 2014, 03:43:07 PM »
Look at this PM I just got from newbie "Turbo":

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I do not know your name, but i think you should stop posting to this board because you transfer your faulty and limited old fashioned ways of thinking onto the newcomers which causes problems.
You have two options, one quit with it, and two, learn the real deal.
Do you even read what someone posts before jumping up and start quoting what is said to then press through your pre historic view on electric energy transfer?
I am dead serious you do not even understand 0.0000000001% of this whole thing.
You think you know but let me tell you,

You don't know shit.

That gets a ROFL for sure! Come on, Turbo, tell us another one.

(I think it is absolutely HILARIOUS that someone can sit at a COMPUTER and tell electrical engineering professionals that the concepts they used to design and build COMPUTERS are wrong... but he can't show _anything_ that has ever been made to work using his own concepts.)


Hey... I just realized something. In a place where there is no Space, you don't need to put gasoline in your car, because everything is really REALLY close... and you can just walk to wherever you are going. And if there is no Time.... you'll get there at the same instant you left. This will really revolutionize travel, and put the Big Oil Powers That Be completely out of business.