Brads Electronic Projects Forum

Guidebook for TDK Inductors & Noise Suppression Components

What really is an inductor?

An inductor is actually just another name for a coil. Inductors are known as such because, to use a technical term, they have inductive properties. That is, it can be
observed that when an electric current flows through a coil, it produces a magnetic field; or when a magnetic field passes through a coil, it produces an electric current.

http://www.global.tdk.com/news_center/p ... a60300.pdf

Chuckt wrote:Guidebook for TDK Inductors & Noise Suppression Components

What really is an inductor?

An inductor is actually just another name for a coil. Inductors are known as such because, to use a technical term, they have inductive properties. That is, it can be
observed that when an electric current flows through a coil, it produces a magnetic field; or when a magnetic field passes through a coil, it produces an electric current.

It's like a mass you use for its inertia. It takes force (voltage) to get current going in the inductor and to get it stopped. Now in the mechanical analogy, you can imagine all kinds of applications where mass is used to determine a resonance, get more force (by stopping it suddenly, like with a hammer hitting something), smooth out a motion by impeding changes in the speed or direction of something, etc.. There's more to it, like when we get into a signal in one inductor getting into another one that is at least loosely coupled to it.

Trying to explain inductors to students can certainly be tricky.

Who would have thought that a simple coil of wire could take so much explaining!

What gets even harder is to convince relative newbies to digital design that a short, straight piece of wire has significant inductance which can get you into trouble, and the effects of transmission lines, and that a fill in PCB design does not qualify for a ground plane.

brad wrote:Trying to explain inductors to students can certainly be tricky.

Who would have thought that a simple coil of wire could take so much explaining!

“Engineering is about learning new things, and learning new things is about spending a bunch of time not knowing what you are doing. “

"When I was a young engineer, it bothered me that I didn't know what I was doing, so I studied very hard. Sure enough, after a couple of years, it didn't bother me any longer that I still didn't know what I was doing. After doing this for over thirty-five years, I am at the point where I find that I am probably feeling bored if I am not feeling stupid. So revel in the ride! It means you are learning something."

LEARN DIGITAL DESIGN WITH PSOC, A Bit at a Time, Dave Van Ess

I've probably been reading about electronics for eight years and I still don't know what I'm doing and I find that a lot of simple instructions are written not for newbies but people who already know what they are doing.

Garth wrote:What gets even harder is to convince relative newbies to digital design that a short, straight piece of wire has significant inductance which can get you into trouble, and the effects of transmission lines, and that a fill in PCB design does not qualify for a ground plane.

That's exactly right, and then you have to also think about the capacitance between tracks!

Yes, there's transmission-line coupling (which involves inductance) between tracks (traces) too, unless the distance between them is a lot more than the distance to the plane.

Here's a page on crosstalk from high-speed digital-design industry guru Dr. Howard Johnson: http://www.sigcon.com/Pubs/straight/crosstalk.htm . Note that if you feed an edge, let's say a positive-going one, onto an aggressor line, and look at the signal induced at one end of a nearby victim line, then change to feed the same signal from the opposite end of the aggressor line instead, the polarity of the signal in the victim line will flip, showing that the coupling is not capacitive. (If it were merely capacitive, the coupling could only be positive.) He says, "The polarity reversal indicates that the interference is due in great measure to mutual inductive coupling."

I guess these are the things that you don' think about when first venturing into electronics I know I sure didn't!