INDUCTORS: Practical Applications - Where do you use them?

[superflux]

There isn't a lot of information on inductors and they seem to be a mystery to most.

For those that use them, can you tell us what application you're using them for and what is the purpose of the inductor in your application?

Thanks!

SF

 

[mneary]

If you haven't seen much information about inductors, you need to change where you're looking.

 

[superflux]

That was extremely helpful. Thank you for your valuable insight. Case closed....

 

[crutschow]

No need to be snippy. Your question implies that you haven't looked very much, and they are certainly no mystery. To be more specific, have you Googled inductors and looked at any of the large amount of information that shows up? Wikipeda has a very good tutorial. After you read some of that and still have questions, then get back to us.

 

[mneary]

Carl,

Thank you for filling in where he should look. My note was unnecessarily brief and could have been much more positive.

Mike

 

[superflux]

I simply want to know what projects people here are using Inductors for. I have Googled for inductors, but there are no real good examples for their usage in smaller projects which seems to be the format of this forum.

Wikipedia states that they're used a lot in signal processing, but doesn't give good examples of this.

 

[crutschow]

Okay, here's a list of a few typical uses for inductors: energy storage/filter in switching regulators, RF coils for filtering and oscillators, EMI suppression in electronic circuits, crossover filters for speakers.

 

[superflux]

I'm not trying to get into with you guys, I just wanted some detailed input from people stating something like "hey, I was having issues with THIS, so I used an inductor.... and this was the outcome."

I will continue to search the net for projects with them. Thanks for responding so quickly...

 

[MrAl]

Hi there,


Dont feel too bad as many people have a harder time with inductors than with capacitors for some reason. It just takes a little time and patience to understand them a little better. You'll do just fine if you are willing to invest a little time studying these amazing devices.

The simplest place to start is usually an inductor in series with a resistor, in series with a voltage source like a battery. You can then look at how the inductor charges up and discharges when the circuit is changed a little. If that sounds too involved then you can start with a voltage source like a battery and just the inductor, then look at how the inductor charges up.

You might also think about it a little and ask some more specific questions about the inductor, like the the units used for inductance.
To start with, the unit for capacitance is the Farad, and the unit for inductance is the Henry.

 

[superflux]

Thanks, MrAl. I have seen the example of the inductor with the light bulb that you speak of. What doesn't make sense is why you would want to create a magnetic field close to other circuitry. Won't that in itself create problems?

 

[mneary]

I have seen the example of the inductor with the light bulb that you speak of. What doesn't make sense is why you would want to create a magnetic field close to other circuitry. Won't that in itself create problems?

An inductor in series with a triac (which is in turn controlling a light bulb) will control the rate of current increase while wasting a minimum of power. Proper inductor design minimizes radiated energy, and the controlled rise time blocks noise (high harmonics) from propagating back into the power source.

A magnetic field close to other circuitry isn't a problem if some simple factors are considered. First, the inductor can be designed to contain that field. Second, if it's cheaper, the circuitry can be made less sensitive to the field (making the axis perpendicular is very effective.) Toroid shaped cores are especially good at enclosing fields.

 

[MrAl]

Thanks, MrAl. I have seen the example of the inductor with the light bulb that you speak of. What doesn't make sense is why you would want to create a magnetic field close to other circuitry. Won't that in itself create problems?

Hi again,


Well, we dont decide to use an inductor so that we can interfere with nearby circuits, we use it for it's desirable properties and try to deal with the side effects. The interference, when it actually occurs, is a side effect that we deal with one way or another in order to obtain the benefits. Some types of inductors are worse than others too, but some like toroids have almost the entire field contained within the core metal so it doesnt affect other circuits as much.
Today there are a huge number of products on the market that use inductors, and without them i think we would all be quite lost

 

[Hero999]

Here's a few inductor projects I can think of:

Boost converters:
Joule Thief, run a blue or white LED which requires 3.5V off a 1.5V battery.
Laptop power supply, power a laptop which requires 19V from a 12V car battery.

RF circuits:
Crystal radio.
FM transmitter.

I'm sure someone with more imagination than me can think of many more.

 

[superflux]

I'm soaking all this up like a sponge.

Take for instance the "Joule Thief". I love watching the videos on it - they build it without any explanation whatsoever. Can I assume that the inductor is building up energy over and above that of the battery and when the diode reaches it's forward voltage, then it lights for a split second, then just continues that cycle? What would be a common Henry value for something like the inductor in the "Joule Thief"?

 

[Hero999]

Some Joule Theif circuits use an inductor and a couple of transistors which form a type of astable multivibrator, most use a transformer which forms a blocking oscillator - an explanation can be found using your favourite search engine.

 

[shortbus=]

Good information on inductors and how to calculate is available in the ARRL(American Radio Relay League) Handbook. To me a must have book in your library.

Before switch mode power supplies became common, Inductors were most often used in radio circuits.