# Re: Hmmm, I'm a little lost here.

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>> Original poster: "Garry Freemyer" <Garry-at-NDFC-dot-com>
>>
>> I got a difficulty here. I need enough wire to wind around a 6" form to
>> create a wound area 30" high and the guage can be anything between #22 and
>> #28 and I need it in feet or pounds.
>>
>> I called Beldenwire and they said the had max 1000 feet rolls of #28 guage
>> wire which is about a pound of wire.
>>
>> They said they have a two pound spool of #24 guage wire that is about 1000
>> feet.
>>
>> So they are saying the maximum feet length of wire they sell is 1000 feet.
>>
>> This is hard to believe since I've seen 10 pound spools with the name
beldon
>> on it.
>>
>> Do you think that this 1000 feet of #24 guage wire would be enough for this
>> size secondary?

To find a ball-park length of wire necessary to wind a secondary coil, do
this:

1. Find the circumference of your coil-form in inches. (Measure the outside
diameter of the coil-form and multiply that value by "pi")

2. Look on a wire-size chart to see about how many turns per inch the
wire-gauge you want to use gives.

3. Multiply the number of inches of wire you want to wind on your coil-form
by the number of turns per inch the chart gave you for the wire-gauge
you're using. That will give you the total number of turns for your secondary.

4. Multiply the total number of turns by the circumference of your coil.
That will give you the total number of inches of wire you will use.

5. Divide the total number of inches of wire by 12 to get the number of
feet of wire you will use.

6. Look back on the wire-chart and see how many feet per pound the
wire-chart gives for gauge you want to use.

7. Divide the number of feet of wire you calculated by the number of feet
in a pound you got from the wire chart. That will give you the approximate
number of pounds of wire you will need.

The number won't be exact because wire-insulation thicknesses vary, and
that means that number of turns per inch will vary...but not too much.
There are other parameters that could be calculated more exactly, but this
way will work fine :)

6-inch coil form
30-inch winding

This calculation will be for 26-gauge wire.

Let's say I measure the outside diamter of my coil form and I find that
it's 6.25 inches (it's happened in the past ;)

6.25 x pi = ~19.6 inches (That's 19.6 inches of wire per turn)

Looking at Matt Behrend's web-page
58.0 turns per inch for 26-gauge wire.

30 inches x 58 turns per inch = 1740 turns for the secondary coil.

1740 turns x 19.6 inches (the circumference of the coil-form) = 34104
inches of wire.

34104 inches / 12 = 2842 feet

Back at wire-chart, I see that 26-gauge wire is about 1300 feet per pound
of wire.

2842 feet / 1300 feet per pound = ~2.19 pounds of wire.

Hope this helps,

Dan

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