This soldering station is quite interesting, especialy for that price.
I got it for about 35€ plus 13€ for 5 extra tips.

1. Soldering Station, from eBay-user: vst-store
2. Soldering Tips, from eBay-user: zqualj

The tips have the ceramic heating element included. The temperature is measured via the resistance of the PTC heating element. In cold state it has about 8Ω, @ 330°C (measured) it has about 16Ω.

This design has 2 major disadvantages:

1. Every tip has its own heating element, with it's own characteristic. Therfore there is allways a different temperature error. I have measured 6 different tips with a thermocouple temperature sensor at a constant setting of 400°C. The results were between 335C° and 365°C.
   As a workaround one can use a lookup table for each tip, which is a bit unpractical.
   Edit: there is an adjustment potentiometer at the controller. Therefore the Error can be reduced to about ±15°C.
2. Since the temperature is measured in the heating wire, that wire is held at a constant temperature. Due to the thermal resistance from the wiire to the tip a big temperature drop is the result on heavy thermal loads. Numerically spoken: The thermal power is reduced by 60%, compared to the ERSA Multi-TC, which has also a nominal power of 75W and a dedicated temperature sensor behind the tip.