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09-01-2013, 05:14 PM
 wayne.ct Silver Member Join Date: Jan 2011 Posts: 552
This is out of my league

Correcting my error and still using 750 KHz as my center frequency, this is what I get...

Calculation #1

L = Total length of coiled wire

L = c/w = 299,792,458 (meter / second) / 2 * PI * 750,000 (/second)

= 299,792,458 / 2 * 3.14159 * 750,000 (meters) = 63.62 meters = 63.62 meters / .3048 (meter / ft)

= 208.7 feet

Calculation #2

L = Length of each turn = 208.7 feet / 20 = 10.44 feet = 10 feet 5.23 inches

Calculation #3

Circumference C = L; Diameter = Circumference / PI = 3.32 feet = 3 feet 3.86 inches

H = Coil height = 0.2 * Diameter = 0.2 * (10.44 feet / PI)

= 7.97 inches

Calculation #4

Max diameter of wire. Space between strands of wire is 62 percent of wire diameter.

20 turns take 7.97 inches ===> 1 turn takes 7.97 inches / 20 = 0.4 inches

0.4 inches = 162 percent of wire diameter ===> 100 percent of wire diameter = 0.4 / 1.62

Wire diameter = 0.246 inches (max.)

AWG 3 has a diameter of 0.2294 inches / 5.83 mm.

AWG 3 has resistance of 0.646 ohms / Km. which is 0.197 mOhms / ft.

For 208.7 ft, the coil will have 395 mOhms or 0.4111 Ohms resistance.

Now we have a manly sized inductor! 'Sorry to say I will not be building that any time soon! Thanks for the ride!

At the same time, my intuition was telling me this was going to be a large coil. So, I feel a bit better knowing my gut was in the ballpark.
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