Re: 3D Print Roller Inductor... perhaps not.... but ...


Jim, N5IB
 

Results of some experiments with variable inductance:

Test coil - 24 turns AWG22, 1" diameter, 1.4" long (~17 turns per inch)
wound on a "natural" PLA 3D printed coil form (photo attached)
L = 7.4 uH, Q = 296

Inserted a 3/8" aluminum rod to completely fill the 1.4" length
L = 6.6 uH, Q = 221, Lmax/Lmin ratio = 1.12

Replaced the Al rod with an array of ten T37-2 iron powder toroid cores
L = 9.2 uH, Q = 318, Lmax/Lmin ratio = 1.24

Replaced the Al rod with a 3/8" ferrite rod (unknown mixture)
L = 31 uH, Q = 271, Lmax/Lmin ratio = 4.2

L and Q measurements were made by resonating the coil with a 33 pF polystyrene capacitor and measuring the resonant frequency and the 3 dB points.

Jim, N5IB

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