Making inductors...

[piyushalbert]

Hi.. to all

I am an Electronics student, I usually came across many circuits having inductors, especially the communication circuits.

i want to ask how to make an Inductor of any particular value like xyzHenry., Please tell me in details which gauge wire to use, how many turns, dia of rotation,medium in between etc etc... and also effects of these parameters on inductance values.

Thankyou

 

[jrz126]

Inductor - Wikipedia, the free encyclopedia

 

[MattQ]

How to make inductors? Buy them off of Digi Key, duh!

Wire gauge will effect the resistance of the wire, and how much current it can handle, but the number of turns, diameter, and dielectric used in the core will be what will effect the actual rating of the inductor. Inductors work similar to electromagnets, and can be described by using Maxwell's equations.

 

[piyushalbert]

Anybody...any technician
who has hands on experience on making inductors please reply to my thread.

 

[colin55]

The only real way to make an inductor is to get a sample and copy it exactly.
As explained above, just knowing the inductance is not enough. You also need to know the resistance of the winding for some circuits. An inductor is one of the most complex and difficult things to make. That's why the simplest discussion would take 100 pages.

 

[MrAl]

Hello there,


There are various little rules of thumb like, the inductance varies as the square of the turns ratio, but it's usually just better to have a formula or two.
For what you are talking about it sounds like you want to make air core coils and there are various formulas on the web for doing this. You basically decide how much inductance you want and then use the formula to figure out what a decent diameter would be and number turns as well as wire size. The number of turns affects the inductance and the wire diameter affects the current carrying ability of the coil. The choice of diameter is interesting, because for a given inductance i think there will be an optimum radius r where when using that radius you get the least resistance for a given inductance value (micro Henries).

Take a look on the web and see what you can find, and if you cant find anything i'll post a few formulas you can try. We can also try some optimization to see what radius works best for a given formula and coil shape.

For solid core coils (with some kind of metal or similar core rather than air) the procedure gets a little more involved, but most manufacturers these days provide the designer with a reference value for a given core usually known as AL. Knowing this value for a given core allows a little faster design to get the required characteristics you are looking for. A little trial and error and you can find a core with the right AL value for your purpose.

I do have to say though, that buying an inductor is much simpler than trying to wind one yourself. There are other things to consider too such as finishing varnish or whatever that make the coil more durable. This is true for solid core inductors, but for many air core inductors hobbyists usually wind their own unless they want especially high Q.

Just to get you started here is one formula for a multi layer air core cylindrical known as Wheeler's Formula:
I=0.8*(R^2*N^2)/(6*R+9*L+10*B)
where
R is the mean radius,
L is the length of the coil,
B is the build,
all above in inches, and
I is the inductance in micro Henries.

We could also solve the above for N and we get:
N=sqrt(5*(6*I*R+9*I*L+10*B*I))/(2*R)

and we could try to optimize for highest Q by calculating the total length of the wire and try to minimize that length while varying say R while keeping the inductance I the same. I think the optimum comes out when the length of the coil is the same as the diameter, or something like that.

 

[audioguru]

The student said "communications circuits" (telephones?) but maybe he means "radio communications circuits".