How does TC work and what is the Temperature Coefficient of Resistance?

A coil is at 0.10Ω at room temperature (20°C / 68°F) You vape and the chip sees its resistance is now 0.22Ω So it knows its resistance rose by 0.12Ω Then it calculates using the coefficient of 0.006 that a resistance rise of 0.12Ω equals a temperature rise of 200°C (392° F) And therefore the coil temperature is now 220°C (428°F) (0.22Ω - 0.10Ω) / (0.006 * 0.1Ω) = 200°C (392°F) + 20°C (68°F) [starting temp] = 220°C (428°F) [coil temp]

A coil is at 0.5Ω at room temperature (20°C / 68°F) During vaping the resistance rises to 1.136Ω This is a temperature rise of 212°C / 413°F, from the following calculation: (1.136Ω - 0.50Ω) / (0.006 * 0.5Ω) = 212°C (413°F) + 20°C (68°F) [starting temp] = 232°C (450°F) [coil temp]

Of course it is performing these calculations many times a second, constantly monitoring the temperature and adjusting the power it sends accordingly.

What wires besides Ni200 could we use?

Titanium (Grade 1)

Stainless Steel (SS317L)

Dicodes' Resistherm NiFe30





It is already being used for TC vapes (existing ECF thread:



With a corrected coefficient this will no longer be necessary - the real desired temperature can be set.



The advantages of Titanium over Ni200 are various, including enabling the use of micro/contact coils (not spaced) and higher resistance ranges. It's also stronger and won't break easily like Ni200 often does. Downsides with currently available wire is that it's springy as hell until (lightly) torched/pulsed.



Another potential advantage is safety; some metallurgists are identifying Titanium as being particularly safe, perhaps on a par or even more so than Kanthal. But understanding of vaping wire safety is still very much in its infancy.



Much more info is in the Titanium thread linked above.​ Titanium has a coefficient of 0.0035, just over half compared to Nickel's of 0.006.It is already being used for TC vapes (existing ECF thread: Titanium wire, vaping and safety .) It's possible to do this on normal TC mods but to do so requires a temperature offset of around 90°F - ie. one would set 340° when one wanted 430°.With a corrected coefficient this will no longer be necessary - the real desired temperature can be set.The advantages of Titanium over Ni200 are various, including enabling the use of micro/contact coils (not spaced) and higher resistance ranges. It's also stronger and won't break easily like Ni200 often does. Downsides with currently available wire is that it's springy as hell until (lightly) torched/pulsed.Another potential advantage is safety; some metallurgists are identifying Titanium as being particularly safe, perhaps on a par or even more so than Kanthal. But understanding of vaping wire safety is still very much in its infancy.Much more info is in the Titanium thread linked above.​





This means that SS can not be properly used for TC without adjusting the coefficient - its resistance increases with temperature too little for normal mods, that are expecting Ni200, to use effectively.



Some people have vaped SS on normal TC mods, and it does somewhat reduce dry hits, but it will still burn cotton. To use it effectively, a coefficient adjustment is necessary.



Once the coefficient is adjusted, Stainless Steel works well - no burnt cotton. However my testing thus far has still required a temperature offset, albeit not as much as people have had to do with Titanium. When using the Infinite Nickel Purity feature, I have set an offset of around 50°F when using SS.



The advantages of Stainless Steel versus Ni200 are the same as for Titanium - micro/contact coils, higher resistance ranges, stronger. The advantages of SS versus Titanium is that it's much easier to work with - malleable, easy to coil. It is also readily available, and cheap.



The safety aspects of it are unknown at this point in time, though theoretically it should be safe at TC type temperatures (and perhaps safer than Ni200, though don't quote me on that!)​ Stainless Steel has a coefficient of 0.00094, less than one-sixth of Nickel's.This means that SS can not be properly used for TC without adjusting the coefficient - its resistance increases with temperature too little for normal mods, that are expecting Ni200, to use effectively.Some people have vaped SS on normal TC mods, and it does somewhat reduce dry hits, but it will still burn cotton. To use it effectively, a coefficient adjustment is necessary.Once the coefficient is adjusted, Stainless Steel works well - no burnt cotton. However my testing thus far has still required a temperature offset, albeit not as much as people have had to do with Titanium. When using the Infinite Nickel Purity feature, I have set an offset of around 50°F when using SS.The advantages of Stainless Steel versus Ni200 are the same as for Titanium - micro/contact coils, higher resistance ranges, stronger. The advantages of SS versus Titanium is that it's much easier to work with - malleable, easy to coil. It is also readily available, and cheap. Crazy Wire/The Mesh Company in the UK sell SS 317L under the brand TMC The safety aspects of it are unknown at this point in time, though theoretically it should be safe at TC type temperatures (and perhaps safer than Ni200, though don't quote me on that!)​





They are calling it "Dicodes' Resistherm.." as if they invented it, but they did not. It was created by IsabellenHütte - their info page on it is here:



In one of their manuals Dicodes state that it is easier to work with than Ni200 (what isn't?) I don't know how it will compare to SS and Titanium. Its resistance at 29G is 5.5Ω/metre, making it less than Titanium and Stainless Steel but 4x greater than Ni200.



The data sheet lists it as usable up to 600°C (1112°F) so it certainly has a far higher ceiling than Ni200.



One potential downside is that it currently only exists in one size - 0.28mm/29G - and that may be the thickest that is available any time soon. The manufacturer states the wire goes from 0.02mm to 0.25mm/30G, so Dicodes have already made it available slightly thicker than the manufacturer normally offers. Maybe 32+G would become available in future, but it seems unlikely that 28 and below will, at least unless/until it becomes very successful for vaping.



I have ordered some for testing (€13/10m !! )​ This is a new wire that Dicodes are popularising along with their new mods. Its coefficient is 0.0032, very similar to Titanium.They are calling it "Dicodes' Resistherm.." as if they invented it, but they did not. It was created by IsabellenHütte - their info page on it is here: RESISTHERM® - Isabellenhütte Heusler , and here the datasheet In one of their manuals Dicodes state that it is easier to work with than Ni200 (what isn't?) I don't know how it will compare to SS and Titanium. Its resistance at 29G is 5.5Ω/metre, making it less than Titanium and Stainless Steel but 4x greater than Ni200.The data sheet lists it as usable up to 600°C (1112°F) so it certainly has a far higher ceiling than Ni200.One potential downside is that it currently only exists in one size - 0.28mm/29G - and that may be the thickest that is available any time soon. The manufacturer states the wire goes from 0.02mm to 0.25mm/30G, so Dicodes have already made it available slightly thicker than the manufacturer normally offers. Maybe 32+G would become available in future, but it seems unlikely that 28 and below will, at least unless/until it becomes very successful for vaping.I have ordered some for testing (€13/10m !!)​



Infinite's implementation of TCR modification : Nickel Purity



What is Nickel Purity?

How does Nickel Purity work?

Ni200's coefficient of approx. 0.006 would suggest a value of 60.

Titanium's coefficient of 0.0035 would suggest 35.

And Stainless Steel, whose coefficient is around 0.00094, would use a value of 10.

Titanium on a setting of 35 vapes well, and much better than it does on a normal TC mod (DNA 40/Yihi). However I have found a slightly better vape from increasing the value, up to around 42.

Stainless Steel on a setting of 10 also vapes well, and becomes properly usable for TC for the first time But a temperature offset is still required - around 40-50°F I am finding. I still need to do more thorough testing, including with other attys

With Ni200, a value of 60 would seem appropriate from the scale, but in practice I am finding the default of 70 works a bit better (no doubt that's why it's the default)