Inductive Circuits - The "Classical" Approach

[poynt99]

OK Mike,

If you say so.

.99

[Michael John Nunnerley]

I think I understand what you're saying, but if I understand correctly, you are
describing a resonant tank circuit. i.e. an LCR tank. Only thing is, I don't understand why you say the cap doesn't oscillate. It's an energy exchange between the cap and inductor is it not? The cap and inductor (pure) need each other in order to oscillate.



.99

The concept you have that the cap oscillates is wrong. The inductance rings down and the cap drains down. The inductance creates the frequency not the cap. The cap receives what it sees and throws it back, but the inductance rings down and each time it looses power like a spring, but the cap just takes in what it sees and gives it back. It is the catalist for the inductor to oscillate as in a tank circuit, but an inductor can be made to oscillate without the cap if you hit it hard enough.

New world thinking that has been shown to be right.

Mike

[gyula]

Wrong thread, moved to mike's thread

[poynt99]

Compress a spring it has resistance, charge a coil "only if it has resistance" or it will not charge.

Stretch an elastic band and you have charged it with energy, let it go and it returns to its original form, charge a cap "stretch the charge between two plates" discharge and it will go to zero, its original form.

Now put the two together and they will oscillate, not because of the cap but because of the inductor. The cap catches all that is thrown at it and throws it out to a resistance that it sees "the inductor" and returns to zero, and off we go again, but nothing is perfect, there are losses, and so in time all goes to zero.

THE INDUCTOR OSCILLATES THE CAP DOES NOT; THE CAP IS A TANK FULL OR EMPTY, THE SPRING OR COIL OSCILLATES DOWN TO ZERO

Now have you got it or do we have to go about it in a different way

Mike

P:S: Oh the point of all this! well, the longer you can keep the coil oscillating the more you are going to get for your money

I think I understand what you're saying, but if I understand correctly, you are
describing a resonant tank circuit. i.e. an LCR tank. Only thing is, I don't understand why you say the cap doesn't oscillate. It's an energy exchange between the cap and inductor is it not? The cap and inductor (pure) need each other in order to oscillate.



.99

[sucahyo]

Coil has resonance frequency, capacitor do not. I would analog coil with the resonant box of the guitar which the box will make the string sound louder, where string which has the box resonant frequency will sound the loudest. Maybe capacitor in a guitar is the string tension by pressing the fret, higher frequency can be achieved by lower capacitance value, such as higher freq by shorter string. The guitar will sound loudest only at certain frequency. Just like coil only give max output at certain frequency.

[Michael John Nunnerley]

I have read it several times and I still fail to see the point you are trying to make. You have stated nothing new, obscure or thought-provoking to anyone that is familiar with these components and how they work.

So what was your point?

btw, in specifiying "pure" inductors, I wasn't necessarily making reference to superconductors or resistance. Resistance has little to no bearing on whether an inductor will oscillate or not.

.99

Compress a spring it has resistance, charge a coil "only if it has resistance" or it will not charge.

Stretch an elastic band and you have charged it with energy, let it go and it returns to its original form, charge a cap "stretch the charge between two plates" discharge and it will go to zero, its original form.

Now put the two together and they will oscillate, not because of the cap but because of the inductor. The cap catches all that is thrown at it and throws it out to a resistance that it sees "the inductor" and returns to zero, and off we go again, but nothing is perfect, there are losses, and so in time all goes to zero.

THE INDUCTOR OSCILLATES THE CAP DOES NOT; THE CAP IS A TANK FULL OR EMPTY, THE SPRING OR COIL OSCILLATES DOWN TO ZERO

Now have you got it or do we have to go about it in a different way

Mike

P:S: Oh the point of all this! well, the longer you can keep the coil oscillating the more you are going to get for your money

[poynt99]

I have read it several times and I still fail to see the point you are trying to make. You have stated nothing new, obscure or thought-provoking to anyone that is familiar with these components and how they work.

So what was your point?

btw, in specifiying "pure" inductors, I wasn't necessarily making reference to superconductors or resistance. Resistance has little to no bearing on whether an inductor will oscillate or not.

.99

[Michael John Nunnerley]

Are You Two One Of The Same

To whom are you directing this to MJN, myself or MH?

Capacitors and Inductors are precisely and inversely complementary in nature.

Strictly speaking, inductors do not "oscillate" as you say.

You can also find a capacitor modeled as a spring, and the compliance of the spring is analogous to the capacitance.

The bottom line is there are all sorts of analogies/models for capacitors and inductors.

In the purest sense, they are completely inversely compelmentary, and pure inductors don't oscillate any more than capacitors do.

.99

I think it was obvious to whom I was directing the post, I gave the quote or did I not or are you one of the same, well it does not matter.

You did not read what I said, I specifically said read carefully what I said. but you have not.

You are right, the bottom line is as you say, but we are not talking pure inductors and capacitors or are we into supper conductors on this thread.

I don't think I said that inductors and capacitors are not complimentary, of course they are, and when together in an appropriate circuit, they will oscillate, of course they will.

ELASTIC BAND- CAPACITOR
SPRING- COIL

Think very hard about this

Mike

[poynt99]

To whom are you directing this to MJN, myself or MH?

Capacitors and Inductors are precisely and inversely complementary in nature.

Strictly speaking, inductors do not "oscillate" as you say.

You can also find a capacitor modeled as a spring, and the compliance of the spring is analogous to the capacitance.

The bottom line is there are all sorts of analogies/models for capacitors and inductors.

In the purest sense, they are completely inversely compelmentary, and pure inductors don't oscillate any more than capacitors do.

.99

[Michael John Nunnerley]

Joit:

> I dont think, that Caps do replace Coils.
With Caps you only rumbel the Current/Energy around, and with a Coil you have a EM Field what is more 'elastic' and has inductive Current still.

The capacitor stores the electrical energy in the electric EM field that exists in the space between the two plates of the capacitor.

The coil stores the electrical energy in the magnetic EM field that exists around the coil.

The "elasticity" of the capacitor's electrical EM field will try to sustain voltage, and changing voltage results in changing current.

The "elasticity" of the coils's magnetic EM field will try to sustain current, and changing current results in changing voltage.

Once more the Yin-Yang complimentary relationships between capacitors and coils are revealed.

Time to eat more Spice....

MileHigh

I like to make references between electronics, if we can call it that, and fisical engineering, a capacitor for me is an elastic band, you streach it and you have put energy into it, you let it go and it gives up its energy without oscillation. Now a coil is like a spring, when compressed it has stored energy and when released it gives up its energy and oscillates, one leads with current and the other with voltage, but voltage is the carrier of current, without voltage there is no current. Now think very hard of what I have said and I am not going to go into pages and pages of explination, I am sure you are very intelligent and can work it out for yourself. I eat a lot of spice and I have a lot of friends, real friends, all over the world.

Mike

[boguslaw]

I wanted to see magnetic field around charged capacitor during discharge

[morpher44]

seeing magnetic fields

I'd really like to know how they looks like...

Check this out:

Dailymotion - Magnetic fields exposed - a Tech & Science video

[morpher44]

physics

I don't understand many things.
Could someone explain me how magnetic field around capacitor is different then magnetic field around inductor and how it is changed over time during inductive and capacitive discharge ? Are they any scientific documents about it ? For example : take inductor, charge it and disconnect completely from the circuit instantly, do the same for capacitor. Measure magnetic fields around : shape ,direction and changing over time.
I'd really like to know how they looks like...

Capacitors are not designed to respond at all to magnetic fields.
C = Q/V were Q is charge and V is volts. Magnetism is not in this function.
The charges, however, will respond to magnetic fields, but if they
are inside the capacitor at the time, it probably won't make much of a difference. If you can PULL charges into your capacitor using magnetic
fields, that would be cool.

Inductors are a more complex machine. They have capacitance and inductance really, and hence have a self resonance.

re: scientific documents
A good physics book .. or electronics book might get you going.

If you disconnect a capacitor, it might hold a charge .. but it will
decay because there is an implicit resistance... and hence
it is an RC circuit.
For a suddenly disconnected inductor, you have the LRC circuit
were C and R are implicit values as well.
The inductor will ring-down to equilibrium.
If L is HUGE, this ring-down can take a while.

[boguslaw]

I don't understand many things.
Could someone explain me how magnetic field around capacitor is different then magnetic field around inductor and how it is changed over time during inductive and capacitive discharge ? Are they any scientific documents about it ? For example : take inductor, charge it and disconnect completely from the circuit instantly, do the same for capacitor. Measure magnetic fields around : shape ,direction and changing over time.
I'd really like to know how they looks like...

[poynt99]

Thanks Glen.

Good info!

.99