DC Wave Questions

This type of discussion is pointless and harmful. I've known brilliant people, some at Bell Labs, who had difficulty spelling. Some Engineers and Scientists had excellent command of the language (both English and English!), but weren't as "swift" as the ones with language usage or spelling problems. It's the luck of the draw either way.

It's quite difficult sometimes, but lets all try to be a bit nicer.

Awaiting flames.....

Don

Didn't get what you meant by "de's." It is now somewhat apparent that you mean "differential equations." So ok then, apologies all around.

Actually, I've never worked for Motorola. I didn't even know they had a cafeteria. They have some nice cafeterias at Microsoft, but I've never worked for them, either. You must have me confused with some other guy who's good in the kitchen *and* the garage. It happens.

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.

On Sat, 18 Jun 2005 04:56:59 -0500, John Fields Gave us:

I'd say very much so LESS than professional.

Er - there are cases where the L will be saturated by the DC component.

Ed

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 Sat, 18 Jun 2005 07:35:52 -0500, John Fields Gave us:

You shock no one. You are droll, at best.

Ha! You think your commentary is important? You don't even know how to designate a clock crystal on a schematic properly.

We can only hope that one day you receive a *real* "great shock", you self important idiot.

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.

PLONK!

On Sat, 18 Jun 2005 06:05:34 GMT, ehsjr Gave us:

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.

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"".

Do you always wear blinders?

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 retarded plonk boy. Wrangle that.

I have peeked in upon this thread from time to time from ints inception. It seems so out of the EE mainstream that it is breeding mosquitos.

Bill

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...

Out here... we is stoned... immaculate.

On Sat, 18 Jun 2005 15:35:16 -0500, John Fields Gave us:

Your original post, dipshit. The title of the post. It says (from sed for bounty hunter). Then, you again refer to the "OP" in another post.

Make up your mind. Is it yours or someone else's.

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... :-)