What are you trying to do? Apparently you want to make a 2H tapped coil with taps at 1.2 and 0.7H, but the math doesn't work. With the largest inductor, 47mH, the first tap works out at 0.47H.brianvino said:There is contra indications to make this inductor
If its an inductor for an eq (the tapped thing made me think so), I wouldn't bother : 10k dcr / H is pretty big.brianvino said:There is contra indications to make this inductor
element inductor is 68 mH (not listed on catalogue).abbey road d enfer said:What are you trying to do? Apparently you want to make a 2H tapped coil with taps at 1.2 and 0.7H, but the math doesn't work. With the largest inductor, 47mH, the first tap works out at 0.47H.brianvino said:There is contra indications to make this inductor
yes, you see correct.Mzaar said:If its an inductor for an eq (the tapped thing made me think so), I wouldn't bother : 10k dcr / H is pretty big.brianvino said:There is contra indications to make this inductor
I agree, and it would be much more DIY.gyraf said:Would be MUCH easier and better to wind some wire onto a pot core.
It is tempting to use the higher Al cores, but these are ungapped, with a rather high tolerance (-30/+40%), which doesn't make them suitable for reproductible performance. In addition, the T38 material has a magnetisation curve that makes the inductance fluctuate with level. That's the reason other ferrite formulations are generally preferred in tuned filters, typically N41. This type of formulation, in combination with a gapped core, requires a much larger number of turns (10-15 times more for a given core size), but in the end, the results are better.If you go for e.g. a P30x19 core made with the T38 material (Al=28000nH), some 280 turns of wire (0.1 or 0.2mm) would get you to 2H. That should be handwindable alright - and with much lower resistance..
wind each tap as an individual coil for less leakage C.
Reverse winding or insulating tape won't help about leakage capacitance; if you want to reduce leakage cap with insulating tape, it must be quite thick, then the coupling factor will decrease, more turns will be needed and leakage inductance will increase too. Reverse-winding may make things worse even, if the end of the coil is close to the start.Mzaar said:Well.... winding thousand turns manually over a toroid core is not a pushover...maybe he could try reverse winding or insulating tape for each tap on a pot core if leakage capacitance is a problem but I though it was a problem in RF (hence the basket winding)...are we talking about some pF ?
The leakage capacitance will be distributed differently. When everything is wound on a single core, all the elements are lumped together, primary inductance and capacitance. That creates a resonance at at given frequency. Splitting the inductor in two halves results in two smaller inductances and two smaller capacitances, each one having a higher resonant frequency. That may just be the ticket for shifting the resonance outside the useful range.I don't get it...if you don't use the mutual inductance property of two winding coils on the same core then you gonna need more turns for the second for the same value (L proportional to N²) then more capacitance leakage.wind each tap as an individual coil for less leakage C.
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