Multilayer air core inductor on a rectangular former:

The calculator allows calculating the number of windings of the multilayer air core coil on a rectangular former at the design stage. You can select measurement units - mm or inches, and also AWG or SWG wire number - the wire diameter will be determined automatically. This calculator based on Rosa's straight wire self-inductance formula (formula 9 on p.305) and formula for mutual-inductance between two unequal straight wires from American National Bureau of Standards circular C74 (formula 182 p.273 with error correction). The coil is represented as many parts of straight wires. Calculating the self-inductance of each part, and mutual inductance of each possible pair of straight wire parts and summing it all, we get a self-inductance of the multilayer coil. This is the "virtual winding numerical method" that is the same as in the calculation of multilayer coil with round former. The accuracy of the calculation is to 5%. At a very high value of inductance, it's possible the small hang. See more about source formulas. Many thanksto Robert Weaverfor his great help.

hi i calculated the number of turns = 230 for a 0.5mH inductor having a=13 b=15.2 and l=54 , 18 SWG wire. when i wound the coil using my cnc , the actual inductance came out to be .335mH . can you help me as to what may have gone wrong here

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can you help me as to what may have gone wrong here

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