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"Vape Mods" are a type of atomizer used in e-cigarets. These "mods" can be built basically from scratch. The simplest mods consist of little more than a battery and a coil shorted over the battery drenched in a vegetable glycerin(VG) and propylene glycol (PG) mixture soaked into an organic cotton or silica wick. The circuit is completed when the button is pressed and the coil (often made of nichrome wire) atomizes the PG/VG mixture into vapor.

Vaping has created a diverse DIY community, and intense interest in Ohm's law among many people who might not have other wised been at all curious about electronics.

Here is an Ohm meter designed especially for vaping atomizers.

enter image description here

Coils come in many shapes and designs. The shape, length and thickness of the nichrome wire changes the resistance of the atomizer. The shape of the coil also has an impact on wicking and vaporizing the PG/VG mixture. The coils are often hand-made and designs are shared over the internet.

Here a is guide showing the basic relationship between coil diameter, wire length, wire gauge and resistance. enter image description here

But what about something like this?

There are effectually two coils in parallel and one of them is made of smaller coils.

enter image description here

In theory, any resistance can be reached by having a wire with no coils of the correct length. I would not be effective for vaping, but as I understand it, the only important variables when calculating resistance are the diameter and length of the wire and how many other wires are in parallel or series. enter image description here

enter image description here

But, is that really the whole story? Some of the time a coil touches itself. Wouldn't that make it, effectively, like a lower gauge wire?

And these coils are effectively inductors. Will that have any impact? I suspect the inductance is too low for this to matter, but it's something that I've always wondered.

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  • \$\begingroup\$ This is magnet wire meaning there is a clear thin insulating varnish on the wires. So when you say they are touching, they really are not due to the thin insulation. Don't know much about vaping but possible the coils are used as inductors and not just DC resistance. Could be wrong on that. \$\endgroup\$ – Joel Wigton May 10 '16 at 4:34
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These aren't strategies for changing the resistance. For the most part, the resistance will be determined by the shortest path.

The twists and turns will carry the heat from the resistive parts and distribute it more widely to more liquid surface area. This will change how much POWER the coil can deliver to liquid, and how much vapor volume it will produce without overheating (presumably). This is assuming that there is something limiting the rate of vapor production, like a Leidenfrost Effect or something.

Caveat: This is taking what I know about electronics and making some reasonable guesses about what is going on.

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Firts, note that this has nothing to do with 'atomizing', the correct term is 'vapourizing'.

What happens is that the current heats the metal, which heats the liquids, which are vapourized.

As you state that the circuit can be just a battery, a switch and the coil, the coil is not used as a coil (inductor) in the electronic sense, just as a resistance (like the (old?) filament bulbs).

The requirements for the coil are: - correct resistance - correct amount of surface area in contact with the cotton/liquid - maybe supporting the cotton (your last picture) - maybe an artistic look (second photo)

Within those parameters the designers are free to coil their wire as the like..

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