suppliers?

oh well i was think that was the point..so after you do all your winding you the add another layer of insulation withe your wrap?and then a shield?

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		Quote:			Posted by Nc-Dirty-digger
	fo some reason i thought you could'nt use stranded wire for making coils.. so your telling me you can

AHA!

So you missed the big rant, last summer, about Litz wire.... The theory is that litz wire is more efficient because it can lower 'skin effect losses.'    

My research indicates that proximity effect losses are greater than skin effect losses and litz wire has zero effect on proximity losses. Both contribute to 'distributed capacitance' which is not REAL capacitance although the effects are is if there were a real capacitance Confusing, isn't it! 

The best way to avoid skin effect, is litz wire, and that does not have to be multiple, enamelled, strands of wire. Any multi-strand wire IS litz wire.... even speaker wire. Speaker wire has thick insulation... lowers proximity losses. Some speaker (Litz) wire has silver covered copper strands.... marginally lower resistance:  the cost is too high:

There is the law of 'diminishing return...' you can only do so much, beyond which, it is pointless.

Planar coils, though harder to make, are easier to calculate and have a little less distributed capacitance. And this goes for PI to BFO.

If you have an LCR bridge (not a PIC LC bridge... it is not a real BRIDGE,) you can measure your coil at the lowest possible frequency, then find the natural resonance of the coil, and using your low frequency inductance figure, you can calculate the effective, distributed capacitance.... not that it is big enough to hurt anything. Mostly it is a practice in frustration! 

Multi-strand wire is great! Thick insulation is great.... just keep weight in mind, you do not want 10 pound coil, out at the end of the shaft, you have to find your optimum choice for yourself, mostly. 

goldigger

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		Quote:			Posted by Nc-Dirty-digger
	interesting! i'm gonna get some that i was thinking about using and take a picture of it for you to see and let me know what you think would be the best way to use it/ make a coil. but that will have to wait until later in the week as im working this weekend and do not have the time to do it right now.but if this wire im thinking about works it should be great

Depends on inner/outer diameters, and how much inductance you want, and frequency of pulses... what is recommended, anyway. The system I want to build, will have 4 ohms impedance at 15.36 kHz, so dc resistance has to be kept low with large gauge wire, and would be 41.44 uHys. If I used a 12" outer diameter, 10" inner, and 8 turns would be 39.111 uHys, aprox, while 9 turns (this is 8 turns per inch with 1/8 total insulation,) is 48.93 uHys. So I would rather use 9 turns.... it is safer, and only 4.72 ohms impedance.... independent of dc resistance which at only 25.62 feet of #18 speaker wire, if 10 ohms per 1k feet, is about 1 ohm. I do not recall 1000 ft resistance of 18 gauge. To find your wire length, take the average diameter of the coil and multiply this average dia, by 3.1415, for inches and multiply by number of turns, to get tot5asl length in inches. Change to feet and look on the chart for this gauge wire, divide the total length by 1000 and multiply the 1000 ft resistance. You now have the approximate resistance (dc) of the coil. Try a DVM and see if it corresponds. The 1000 ft figure is for planning, actual resistance can be measured.

If you really think distributed capacitance would be a problem, and you have an LCR bridge, not a PIC inductance meter, you use as low a frequency as possible to find the inductance at 100 ohms (for 40 uHy, it would be 400 kHz,) then find the self resonance, you can calculate the distributed capacitance, which for 9 turns would be insignificant. (Divide self-resonance frequency by the first inductance, and then divide by 6.283, then your answer will be capacitance.)

Next question? 

goldigger

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