5.11.2019

I disassembled the iron and started choosing the controlcircuit and a fitting thermistor.

Since thermistors ready for 300°C are rather expensive I chose one with 150°C limit.

An alternative solution seemed to use an existing thermostat from an baking oven, but they are too big for my purpose.

10.11.2019

I chose the circuit of Oliver Pering:

http://hobbyelektronik.de/praxis/projekte/temperatur-schaltstufe/

I had a nice time calculating resistor values for the voltage dividers used to switch the heating via the OpAmp (the good old workhorse, a historic LM741 ;-) )