hi, found some nice coils but im having trouble calculating the inductance. im looking for .8uh, tried 4 on line calculators but getting widly differing results, (hope this works, i was going to add a nice link to manufacturers page, can someone advise on any copyight issues?)
my son got done once for including a manufacturers pic in an advert)

diameter8mm
coil length8mm
wire size 1mm

has ferrite core but will like to know the inductance as air cored as well,

any help much appreciated

dougal

 

Links are OK, as long as they aren't the image. There is a difference. If someone hasn't stepped in by the time I get home I'll look up the coil formula from my old text books.

 

thanks Bill
the only thing i couldnt get my head around in frequency calculations was powers of ten, so easy to be out by a factor of ten -solved the problem with the windows calculater ,it holds 25 digits so micro and megohms etc are no problem
regards
doug

 

diameter8mm

Is this the inside diameter, or the outside diameter?

coil length8mm
wire size 1mm

has ferrite core but will like to know the inductance as air cored as well

If that was the outside diameter, the inside diameter would be 6mm, and the air inductance roughly 0.28uH (280nH). If it were the inside diameter, the air inductance would be roughly .43uH (430nH)

The ferrite would make that a lot higher. The ferrite material would be the major factor in the frequency range that it was useable in. There are a variety of different ferrite materials that vary in stability, saturation, and a number of other variables. It would take a fair amount of experimentation over a range of frequencies to determine the characteristics.

 

thanks SJT

thatll do nicely

regards

dougal

 

Hello,

Here is some background information about aircoils.
1) with measurements in inches
http://hem.passagen.se/communication/aircoil.htm
2) with measurements in meters
http://info.ee.surrey.ac.uk/Workshop/advice/coils/air_coils.html

Greetings,
Bertus