Cool, my TI wire shipped already from Zipvipf! Nice turnaround from them, shipped about three hours after opening time this morning. I did put a little message with the order, saying it was for an urgent project and I would be so grateful if they could ship fast
I was worried because all the products say "Can ship in 1-3 days." Anyway, all worked out fine!
Your theory looks good but so did mine a few weeks ago... It probably won't work. Besides both materials having a different temperature coefficient, their temp/resistance curve is, most likely, not linear between each other. I found this when I did the water test.
Nickel will read 212F while Titanium reads 210F (2F deviation)
With eliquid, nickel reads 430F (no cotton scorch marks when dried out) and Titanium around 340F
As you can see, the 90F difference applies around temperatures of 400F but not at 200F which can only be explained by different temperature profiles between the two materials.
We really need those companies to start including Ti profiles in their boards.
Ah OK, interesting. Is that a test you described in this thread? I'd be very interested to read more details - do you have a link handy, or could tell me a keyword to search for?
I am an absolute newbie to all of this, and indeed physics and maths in general. But my understanding so far was that:
"Besides both materials having a different temperature coefficient, their temp/resistance curve is, most likely, not linear between each other"
cannot be correct. I understood that the temperature coefficient IS the temp/resistance curve. And that it's always linear - it has to be, because it's derived from a formula; in the same way that resistance increase from thickness of material has to be linear.
(EDIT: I might be wording that terribly, an example of me having no knowledge of even intermediate maths: I suppose 'deriving from a formula' doesn't have to mean 'linear' as such, eg if the formula involves squares - what I mean to say is that the same formula is used for both Ti and Nickel, using a different base number, so in both cases the resistance increase is predictable from the same formula in the same way as long as the right coefficient is used.)
So the Ti coefficient of 0.0035 defines one curve, and Nickel's 0.006 defines another. If temp sensing is done using nickel's 0.006 it will be way off using Titanium, but if the right coefficient is used, it
should then be accurate - just as accurate as it was with nickel.
For some evidence of this, take a look at a Temperature Coefficient of Resistance calculator,
here's an example at HyperPhysics, and
another, simpler. The first at HyperPhysics requires you to enter coefficient in the format
59 x 10^
-3 (you enter 59 and -3, they being the values for Nickel), the latter is simpler and I used 0.006 for pure Nickel - there's a table below the second calculator showing some example values - but not Ti, which would be 0.0035 on the second calc and
35 x 10^
-3 on the second.
There's several such calculators on the 'net and I've played with a few. They all work on the same basis - put in the coefficient number, a starting resistance, starting temp, and then either end resistance or end temp, and it will calculate the other for you. These calculators don't ask for what material you're using, they just ask for the coefficient - that is my evidence that, at least for temperature prediction, coefficient is all that's needed to derive a temperature offset from a resistance offset, or a resistance offset from a temperature offset.
I'll say again that I'm absolutely not an expert, and I emphasised
should above because I guess there definitely could be other things at work in practice.
For example, perhaps assumptions are made in the TC chips about the heating properties of Nickel, such as "apply 20W and it will increase in temp by X" which don't hold true for Ti. So maybe adjusting the coefficient, if indeed NIckel Purity even does that, will help it sense the right temperature, but won't help it achieve the desired temperature because that's controlled by some other fixed variable that can't be adjusted.
But I am pretty sure that the coefficient itself is simple and directly translatable between Nickel and Titanium, as long as the coefficient number is altered. What I'm not at all certain of is whether the Nickel Purity setting even modifies the coefficient!
I have emailed the Geeco guy to ask him - my question was technical so no great hope of help, but perhaps he'll pass it on to someone who knows. I told him I was getting in to YouTube and was a big poster on ECF, in the hope that this would encourage him to help me to get more publicity for his new mod
(Which in fairness, it will - if Nickel Purity does work for Ti, that's going to bring a lot of interest to these new mods that have it.)
I'd be really interested to learn more on the test you did - could you let me know exactly what you did, and/or link me to details?
