Choke Coils

[usif]

Today, my brothers were mucking around with a little Morse Code DIY set, and on the component list it had a Choke coil. In this case it acted like a voltage regulator (The instruction set described it as "A device that changes the voltage of the electricity flowing through it"). A quick Google search on it revealed that they can be used as a filtering device as well.

Does any one here regularly use Choke Coils? Or has used them?

 

[JimB]

Today, my brothers were mucking around with a little Morse Code DIY set, and on the component list it had a Choke coil.
In this case it acted like a voltage regulator

I dont think so.

(The instruction set described it as "A device that changes the voltage of the electricity flowing through it").

That is the worst description of the operation of a choke that I have ever heard.
An inductor (also known as a coil, choke) opposes a change in the flow of current through it.
The reactance of a coil increases with frequency.

A quick Google search on it revealed that they can be used as a filtering device as well.

Does any one here regularly use Choke Coils? Or has used them?

Yes.
Chokes are used in some power supplies to help remove the ripple from the output of a rectifier.
They are used in amplifiers (especially RF amplifiers) to decouple the signal from the supply lines, here they are called RF Chokes.

JimB

 

[usif]

Thanks for the reply, it cleared somethings for me. What confused is the fact that it said it acted like a voltage regulator, and even more this Choke Coil had three pins, (Voltage regulator came to my mind first).

How much pins does a Choke traditionally have, and how much can it have depending on what?

 

[JimB]

A choke/coil must have as a minimum 2 pins, one connection to each end of the coil.

Sometimes the coil may have one or more taps, obviously each tap will need a pin.

It is also possible that the package which the coil is mounted into has 2 or 3 or more pins as it is a standard mounting package.

JimB

 

[MrAl]

Hi,

I regularly use chokes (inductors) in power supplies. These coils store
energy and act as filters.

One way of looking at a coil (choke) is like this...

If you apply a voltage to a coil nothing happens until some time later,
when the current starts to build up step by step. This can happen fast
however with small chokes. Once the current builts up, you cant stop it
too easily. Even if you open circuit the choke that current tries to maintain
itself in keeping the current constant, at least for a short time period.
After a longer time period all the energy dies out.

Thus, the inductor acts like a constant current for short time periods.

If you look at the current as a pulse voltage is applied, you see the current
ramp up in an inductor (coil, choke).

 

[crutschow]

The analogy of inductance in the physical world is the inertia of the mass of an object. It requires a force to get it moving, but once it's moving it tends to keep moving. That's similar to the way current acts in an inductor. The higher the inductance (mass) the slower the current increases (velocity) for a given voltage (force).

 

[Hero999]

Another way of looking at it is: capacitors smooth voltage and inductors smooth current.

In fact when you look at a constant current circuit, capacitors behave like inductors do with constant voltage and inductors behave like capacitors do with constant voltage and instead of using impedance we use admittance but what I've said is probably too confusing for a nube.

 

[usif]

Another way of looking at it is: capacitors smooth voltage and inductors smooth current.

In fact when you look at a constant current circuit, capacitors behave like inductors do with constant voltage and inductors behave like capacitors do with constant voltage and instead of using impedance we use admittance but what I've said is probably too confusing for a nube.

No, dont worry. I understand it, I just needed someone to explain it to me. The way I see it is that nothings too hard if you have the "will to learn".

 

[MrAl]

Hi again,


Another idea would be to learn how to analyze a general circuit
with resistors, inductors, capacitors, and voltage and current
sources. You would get a really good idea how inductors work
while doing this.

For example, if you were to connect a 1vdc ideal source across
a 1H ideal inductor you would measure the following currents:

0A after 0 seconds
1A after 1 second
2A after 2 seconds
3A after 3 seconds
etc.
(note this is a perfect ramp)

The current would keep rising like that. With non ideal components,
the series resistance would limit the current.