Here’s what I know about. Not to imply I know “all” about TC.
There are HUGE differences in what different manufacturers provide and consider temperature control. I can’t help but believe some just claim it on the box with little or no qualification.
There are three main parameters for a DNA that can be adjusted, internal resistance, TCR, and thermal profile. For other boards there are only two parameters, resistance, and TCR. Internal resistance being a function of resistance but not accessible.
Adjusting the resistance or internal resistance by proxy is my preferred method of adjusting the temperature a mod will produce. By adjusting the “cold” or “room temp” or “baseline resistance” all further adjustments done by the mod should be linear, meaning 200°F will be just that as will 450°F. That is a big if. This assumes the mod does a good job of applying TCR changes via it’s firmware.
Adjusting the TCR value for a given temperature will work. If you alter the TCR and get 400°F actual from a setting of 400°F there is a high probability that that 200°F actual will not correspond to 200°F setting. By changing the TCR value you are actually changing the slope of the TCR. Now, here’s a caveat; a complex or exotic build might just have a different slope than simple wire. That is because much of the heating is done via conduction and convection. Steam engine produces TFR slopes for these builds that are not linear as well. Some coil configurations to not respond in a linear fashion. Let’s take it a step further. Steam Engine also provides a “TC precision” value. This is basically a confidence factor of how accurate the “TCR in vaping range” will be. The higher the number the more accurate. No reference to percentage of error even. We have all experienced using two identically specified strands of wire from two vendors and found we get slightly different resistances. DJlsb hints at some of these considerations when he publishes temperature achieved for single coil and then double coil. That is really only part of the story. I have not seen any reports on linearity of devices across the vaping temperature range.
All of this makes my head spin to be honest. I have relegated TC to these simple parameters. Can I get the mod to produce and hold close to 420°F? Can I get the mod to prevent dry hits? Will the mod provide a smooth even vape? Can I get the mod to stay in TC mode? If I can satisfy these parameters, I will use the mod in TC. If not I consider it to be a VW mod only.