Inductance values for various designs
The pictures below show various different pulse transformers that were tested. The core type and winding method are listed along with the measured inductances.
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Ferrite toroid. Ferroxcube 4330-030-34600 (UK Farnell part 305-6995) Dimensions: OD=25.8mm ID=14mm W=10.6mm Material: 3E25 Spec Ind: 5620 nH 9 + 9 + 9 turns of multi-stranded wires wound in seperate bundles spaced 120 degrees apart around the toroid. Lp = 533.6 uH, L1 = 4644 nH, L2 = 3689 nH, Lp/L1 = 115, Lp/L2 = 145 |
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Ferrite toroid. Ferroxcube 4330-030-34600 (UK Farnell part 305-6995) Core spec as above 9 + 9 + 9 turns of multi-stranded wires interleaved around the core. The combined winding was spread equally around the circumference of the toroid. Lp = 523.2 uH, L1 = 233.4 nH, L2 = 199.7 nH, Lp/L1 = 2240, Lp/L2 = 2620 Note: the massive reduction in leakage inductance values L1 and L2 ! |
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Ferrite toroid. Ferroxcube 4330-030-34600 (UK Farnell part 305-6995) Core spec as above 9 + 9 + 9 turns of multi-stranded wires tightly twisted together. This "twisted-threesome" was then wound evenly around the circumference of the toroid. Lp = 520.6 uH, L1 = 208.1 nH, L2 = 160.9 nH, Lp/L1 = 2500, Lp/L2 = 3240 Note: the further reduction in leakage inductance values L1 and L2. |
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Ferrite toroid. Ferroxcube 4330-030-34600 (UK Farnell part 305-6995) Core spec as above 9 + 9 turns of 3mm lapped-screened wire interleaved around the circumference of the toroid. Screens connected in parallel to form primary winding. Centre cores used as secondary windings. Lp = 528.4 uH, L1 = 124.8 nH, L2 = 67.6 nH, Lp/L1 = 4230, Lp/L2 = 7820 Note: the exceedingly low leakage inductance values L1 and L2. Probably dominated by stray inductance in the leads to the core. |
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