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Post by ms on Feb 22, 2017 6:15:26 GMT -5
I've been reading about coil capacitance, and I came across an interesting revelation here coil32.net/theory/self-capacitance.htmlWhat this is saying is that the windings only capacitively couple with their neighbors who are perpendicular to the axis. So if you have a pickup sitting on a table, windings capacitively couple with windings to their left or two their right, but not above and below. The interesting thing about that is that it means a single layer coil has about the same capacitance as straight wire, because such a coil only has neighboring wire above and below. Of course a pickup is multilayer, but the point of it all is that the winding capacitance is limited to one plane throughout the coil. A practical application is that if you want to manufacture low C coils, some sort of layer spacers, or spacing agent, might do the job, such as a layer of lacquer or wax. You wind, then dip, then wind, then dip, etc. Straight wire? Equations 3 and 4 in your reference contain the diameter of the coil, not the length of the wire. I do not understand that relationship. Any way, this is for single layer coils; very different for a guitar pickup.
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Post by antigua on Feb 22, 2017 12:55:37 GMT -5
Straight wire? Equations 3 and 4 in your reference contain the diameter of the coil, not the length of the wire. I do not understand that relationship. I misunderstood this line "Hence, when considering the physical processes in a single-layer coil at frequencies close to the frequency of its self-resonance it is necessary to abandon the model of lumped elements as baseless and to consider the inductor as a transmission line." but after reading again they just mean that the capacitance doesn't compound, but increases in proportion to wire length. Any way, this is for single layer coils; very different for a guitar pickup. Right, but as I said, the nugget of information is that the capacitive coupling occurs perpendicular only, no matter what kind of coil is being discussed, so that creative methods of insulating windings coil make use of this fact to most efficiently shield the wire. As it says, shielding turns within the same layer is ineffective, but shielding turns of different layers would be effective. It strikes a blow to scatter winding as a means of reducing capacitance, because how much perpendicular space are you adding by simply crisscrossing the wire a little bit more? It would be a lot of work, but if a CNC coil winding machine could stop every so often to somehow create a coating or layer, then resume winding, you would have lots of perpendicular spacing, and relatively little parallel spacing. You'd block the vector of the electric field that causes the capacitance, and ignore the direction in which doesn't lead to capacitance.
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Post by ms on Feb 22, 2017 13:27:01 GMT -5
Straight wire? Equations 3 and 4 in your reference contain the diameter of the coil, not the length of the wire. I do not understand that relationship. I misunderstood this line "Hence, when considering the physical processes in a single-layer coil at frequencies close to the frequency of its self-resonance it is necessary to abandon the model of lumped elements as baseless and to consider the inductor as a transmission line." but after reading again they just mean that the capacitance doesn't compound, but increases in proportion to wire length. Any way, this is for single layer coils; very different for a guitar pickup. Right, but as I said, the nugget of information is that the capacitive coupling occurs perpendicular only, no matter what kind of coil is being discussed, so that creative methods of insulating windings coil make use of this fact to most efficiently shield the wire. As it says, shielding turns within the same layer is ineffective, but shielding turns of different layers would be effective. It strikes a blow to scatter winding as a means of reducing capacitance, because how much perpendicular space are you adding by simply crisscrossing the wire a little bit more? It would be a lot of work, but if a CNC coil winding machine could stop every so often to somehow create a coating or layer, then resume winding, you would have lots of perpendicular spacing, and relatively little parallel spacing. You'd block the vector of the electric field that causes the capacitance, and ignore the direction in which doesn't lead to capacitance. I have thought it is possible that scatter winding lowers capacitance because there are no well defined layers, but I have to admit that I know less about coil capacitance than I thought I did!
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alexirae
Rookie Solder Flinger
Posts: 2
Likes: 0
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Post by alexirae on Apr 11, 2017 7:14:21 GMT -5
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Post by antigua on Apr 11, 2017 13:29:05 GMT -5
Maybe it's a DNS issue, I'll get it working again. I also have more pickup data to enter, I'll post an update later today I hope.
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alexirae
Rookie Solder Flinger
Posts: 2
Likes: 0
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Post by alexirae on Apr 13, 2017 3:11:04 GMT -5
It seems to work now Awesome work man!
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Post by antigua on May 9, 2017 22:48:08 GMT -5
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Post by antigua on Jan 14, 2018 1:44:05 GMT -5
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