# Help with coil winding

1. Sep 23, 2008

### shovel52

I am trying to gather some info about winding inductors. This is not simple. I am trying to put together a resonant circuit to power a water fuel cell. I know a lot of people will say that this is bull but I dont care , I am having fun with it and am learning a heap. The circuit uses a bifilar choke. The specs on the choke are

2x190 turns of 5/10mm magnet wire #24 on a 20mm cardboard tube 190 mm in length

he says this is a 240 mh coil "I am assuming he means mili henrys"

I have posted 2 links at the bottom of the page. One is to the water fuel cell designer and the other is to an inductance calculator.

I have input this gentlemans specs. on his inductor into the inductance calculator and I get
133 micro henrys. Unless I am doing something wrong, something is wrong.
Please have patience here I do have a back ground as an electronics tech but I am a beginner on the design work.

There is a big difference on inductance here. I have wound a similar choke using 1/2 inch pvc pipe and 200 turns of #22 wire. I bought a cheap inductance meter off of ebay and have hooked it to one side of the inductor, and I get a reading of 1.9 on the 20 milihenry range
and 3 on the 200 milihenry range. The meter has no over range function like an ohm meter , all it does is move the decimal point. So I have no idea the value of my inductor?
I would assume it would be close to his at 246 mh?
I have seen math equasions for calculating inductance but no one uses examples. Examples are the only way people can learn. but you dont see any. Would anyone here have any input? Ideas or examples to calculate the inductance of this mans inductor? thanks John

http://jnaudin.free.fr/wfc/index.htm

http://www.66pacific.com/calculators/coil_calc.aspx

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