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[A thought] Could a thermistor/thermometer be used to learn ANY temp controllable coil's temperature coefficient of resistance???


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I think a little USB add-on device with some sort of thermistor (or IR thermometer) could (with escribe integration) be used to callibrate an unwicked coil's CSV values... "the coil is X degrees RIGHT NOW. Its resistance is Y ohms right now... At various temperatures... Repeat for reliability" The process would probably involve a minute or two of automagic heating+cooling cycles, but I think it would make all of the calculator voodoo obsolete. Evolv, have you played with an "off-line" (plugged into the PC, not vaping) temperature control calibration process? I think it could allow oddball coils that the calculators don't even support, like Ni200+Titanium twists.

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Wish it was so easy.. but it doesn't seem so.. Check sweetspotvapors TCR calibration setup .. I guess for accuracy you need professional equipment. I have a temp probe multimeter and doing some experiments but it is slowwwww in updating and can't get accurate readings.. yet .. 

https://instagram.com/p/6tk4ERuFzM/

https://instagram.com/p/6uARg8uF5B/

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There's a better way to do this. 

Get a decent thermometer or thermocouple, a glass flask, a heater (or do it on the stove) and some oil. 

Run wires extension wires (kanthal is best of the easily available stuff, it has a very very small TCR) to the coil and back to the DNA 200. 

Fire up atomizer analyzer. Short the kanthal together at the far end to get the resistance of the kanthal and mod. Then connect the kanthal to the coil under test. 

Put the coil in the flask, fill the flask with the mineral oil and put the thermometer measuring the oil temperature. Put the whole apparatus on the stove. 

Don't start a fire. Use an oil with a high flash point and low conductivity. Silicone oil works best, but it is a bit spendy. Transmission fluid works if you keep it under 450F or so. 

You can use this sort of setup to generate a TCR curve for anything with a little care and practice. The oil is easy to measure, and it keeps the coil at a nice uniform temperature. Stir the oil so you don't get hotspots and don't set your thermometer on the heated bottom. 


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  • 3 weeks later...

Very interesting idea John, I'm going to have to try that.

That said, I've had no problem doing it with non-professional, highly affordable equipment

I paid £50 for the UNI-T UT325 thermocouple ($50 in the US) which can log to the PC via USB, and then I bought a couple of Type K probes for about $8 on eBay. I have some rated up to 250°C, which have <1s response time, and some slightly slower ones up to 350°C.  Though I haven't had a problem taking the 250s to 300 on occasion.

The most important thing I've found is to touch the probe to the coil, so I use a widely spaced coil and helping hands or similar to get the probe touching one wrap of the coil.  In the past I've also experimented with using silica or cotton wick as padding to press the end of the probe to the wire.

Here's a photo I took a couple of months back when I was probing the DNA 40 to measure the required offsets to vape Titanium on it.  (The second probe was for background temperature and is not necessary.)



I'm definitely going to try John's method as well as it sounds smart and might make life easier in some respects.  I just thought I'd mention that it doesn't require professional equipment - and prices - to measure the coil directly, in-situ.  For $58 you have all you need.


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