The fundamental problem with the term "DC sine wave" is that it suggests a way of viewing the situation which is incompatible with finding answers to the posed questions.
To answer the question, the offset AC waveform has to be considered as the sum or a DC voltage and an AC component, with their effects on the R, L, and C analyzed seperately. The L and the C don't care about your DC offset, so you must still think of the signal as AC in order to understand their behavior. They don't care that the overall signal doesn't reverse polarity, they only care that derivative of voltage with respect to time is non-zero.
Yes, and there are even inductors that are specifically selected to saturate and thereby change to a reduced inductance in operation.
Even without a DC offset.
A "hard start" choke in an oscillator circuit that begins at one given inductance, yet has a very small core cross section will provide the shift need to start the swing, then saturate quickly so as to not steal power from the loop. Very important on low consumption miniature power supplies, for example. The inductance keeps the supply from having a hard start issue at power up, yet gets out of the way in normal operation due to the ease at which its overtly small core saturates, shifting its inductance down, which steals less energy from the oscillator.
What you are suggesting is a good issue to keep in mind for the real world (and one I had overlooked).
However, what you have actually said is not true.
An inductance - a specific element we both referred to as L - will not saturate. Rather it will behave in accordance with the simple mathematical model of inductance.
The real-world magnetic device chosen to play the role of an inductor can saturate, and it's something we might need to think about. However the propensity towards saturation would need to be specified by additional parameters beyond a simple constant value of L. While we're at it, we should put in parasitic resistance, temperature dependence, possible effects of external fields, and probably some other things that I'm not thinking about.
If asked to solve a problem with an inductance, you treat it as such. If asked to solve a problem with an inductor, you have to consider the broader properties of that device, of which inductance is only one, and not necesssarily a constant one.
On 18 Jun 2005 06:42:29 -0700, cs snipped-for-privacy@hotmail.com Gave us:
There ARE such cases. In such cases, the L value will drop.
Sure. If one states a fixed L for a calculation, then DC offsets are ignored. Perhaps this is why high frequency inductors are hybrid cores, as opposed to steel or iron as in a low frequency case.
I see what you are saying. You are declaring/regarding it as a mere number that gets plugged into a formula. OK. In that case you are correct... the value is immutable... however...
If one must regard the junction potential of a diode in making a circuit calculation for a circuit which includes a diode, one must also make calculations for the parasitic, etc. effects of other components as well, when designing or discussing them.
The *ideal* circuit scenario is one for the classroom in which the basic fundamentals are conveyed. After that, the instructor immediately conveys the whys and wherefors of the REAL world scenarios making a direct distinction between the two.
Out here, in the real world, one needs to consider real world effects. I see from your explanation and distinction between the two that you know this. So, for the real world...
DC offsets saturating an inductor is most certainly a needed consideration, if the circuit so demands, just as knowing what the on resistance of a transistor is, or the junction potential of a diode in a circuit which contains such elements.
Out here... in the perimeter, there are no stars...
And you are too damn stupid to recognize the component as a oscillator module. The "U" designator is used this way by a lot of manufacturers since it is not a crystal, and at the design level it is just another chip.
On Sat, 18 Jun 2005 10:41:36 -0500, John Fields Gave us:
No. It "boils down" to the fact that YOU do not know how to designate components on a schematic.
They ARE supposed to be easily interpreted, not your "I don't give a crap, as long as my moniker is at the bottom of this page that I earlier claimed was a mere repost of a "someone else's schematic"".
On Sat, 18 Jun 2005 15:42:48 GMT, "Michael A. Terrell" Gave us:
If the retarded twit can critique someone else's spelling, he can handle being called on not designating the crystal (and yes it's a crystal) correctly.
You mentioned the behavior of L and C, which refers to the way the *component* represented by C and the *component* represented by L react. It is in your context that I used the term L. Now, apparently, you have changed the context to exclude consideration of the component (which will sometimes lead to incorrect analysis) and to restrict the term to have it refer to the property only. Therefore, we did not refer to the same thing with the term L.
What I referred to is a circuit element that can saturate, as per the definition for inductance.
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"1. The property of an electric circuit by which an electromotive force is induced in it as the result of a changing magnetic flux. 2. A circuit element, typically a conducting coil, in which electromotive force is generated by electromagnetic induction."
I don't know where you came up with the above "rules" or whatever you want to call them. If, in solving a problem with an inductance, (specifically in this case, the effects of DC on an R,L,C load impedance) no consideration is given to saturation, the solution can be erroneous. Very specifically for the op's question, the possibility of saturation *must* be considered, even though the question did not include the word inductor. I think those rules, or whatever you call them, are not correct.
That's about the same as pointing out that some capacitors are polarity sensitive, and will effectively be a short if the polarity is wrong. It's true, but does not enter into the problem at this point.
Inductors saturate. Inductance doesn't.
To me it is obvious that by L and C, he meant the inductance and the capacitance, not the specific inductor or capacitor.
If he'd have meant a specific device, he have had to specify a few parameters as to just what kind of a device, no?
Exactly, except I don't think he changed the context.
A circuit element, not a component device.
But saturation has nothing to do with the inductance. After the right inductance is calculated, then a specific device has to be chosen, and *that* is when saturation has to be considered. So do physical size, mounting style, insulation, and perhaps other parameters too, none of which are related to the original "inductance" problem.
Could be! I don't remember the OP's question... :-)
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