I’m most of the way to retrofitting my soldering & hot-air station to be a *de*soldering & hot-air station instead. I’ve added the new connector to fit the desoldering gun and wired up the trigger for the vacuum.
Only trouble is the thermistor is different to the type in the original iron (which I can’t find, but the internet suggests is a K type thermocouple?). Hopefully I can work out what type this is and bodge the op-amp circuit to calibrate it into useful range.

#s0Projects #tinkering

Progress! Reverse engineered the analogue section with PCB photos, KiCad and Horizon EDA, then simulating with Falstad Circuit JS... but I haven't worked out what's wrong here yet, I'm not seeing any movement coming out of the first opamp in the sim.

Possibly I've read one of the values wrong, or missed a component entirely? Any suggestions?

I won't be able to work on it for a few days, but here's the data I collected using a resistor decade in place of the existing thermistor/thermocouple and measuring what it produces:

yoooo, I had completely misread several component values and mixed up which opamp output I was measuring. I need a brighter desk light on a gooseneck.

Here's the sim now matching my measurements nicely.

yay, I seem to have worked out how to sort this whole calibration out with one resistor value change (to change the gain on the first opamp stage). The DC offset already has a 10-turn precision pot with enough range to fix the offset part. Woo! time to test...