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    Edgar Kogler • 11/10/2019 at 17:41 • 0 comments

    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 ;-) )