Coil question: Series and parallel...

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spawnsharks

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Am I correct in assuming that wrapping something like the 'figure 8' or any dual coil with a single strand would have an end resistance of the entire length of wire.... and wrapping, say two of these, and putting them in parallel would halve that?

My MVP is limited in it's amperage output, and my sigelei is limited in it's ability to read low ohm coils (So far, I think I prefer higher resistances anyway around 2 ohms)

I just got an Igo-W. I built a dual coil setup, but it's in the 0.9-1.0 range (must be on the cusp, as it reads differently each time).. This is too low for the Sig, and the MVP has trouble getting it hot enough. My plan, then is to build a quad coil setup with two figure 8 style coils in parallel. Can I assume that if I go with 8 wraps on each (16 wraps total), 30ga, I will hit somewhere around 3 ohms (roughly), and two in parallel will net me in the 1.5 range that will fire in my Sigelei?

I ask before I try because I am low on wire, and can't afford to waste it at the moment.
 

jersey_emt

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You got it.

A single strand of wire is like two coils connected in series. The final resistance is based on the total length of wire.

Two strands connected in parallel is a true dual-coil build, and the resistance is one-half of the resistance of each strand. Assuming of course both coils are of equal resistance. If the coils are unbalanced (different resistance for each), calculating the final resistance is a bit more complex.
 

spawnsharks

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Thanks! I was pretty sure this was correct... I have a pretty solid understanding of this stuff, but it's been since high school since I actually had to consider something like that. I think the class was in 1986. Good thing Ohm's Law hasn't changed since then ;)

I ended up going with a traditional dual coil with 34ga. It came in a bit high (2.9 ohms) but the thin wire heats almost instantly, and my Sigelei can push it at 15w.. I will play around and try to find a build that lands me closer to 1.8 or so. I think this means I have graduated to the 100ft roll class.
 
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