Jones Regarding thermistors you wrote [snip] Thermistors, unlike ANY other form of heating that I know of (like resistance tape heating) do NOT require dedicated thermocouple feedback. That is most important, since thermistors can be controlled by monitoring their own impedance characteristics, and this is often done in industrial situations, whereas the lack of apparent control of temperature otherwise, is most problematic. [/snip]
I think even resistive wire could furnish adequate feedback via current sense when you are Using a PWM scheme. The change in resistance with change in temperature would have greater effect on a brief large current pulse Then a static DC level and could be processed in the control box. I would not be surprised if he copied Mills and Langmuir in using tungsten filaments. Fran
