arhi made a control board for HAKKO soldering pencils. Add a power supply, probably from an old PC, and you have a quality DIY soldering station.
From the project log forum:
Upgrades from v1
1. thermocouple is read properly. The circuit used to get the K-type to go 0-5V came from microchip’s app note
2. 3 buttons are replaced with rotary encoder with button
3. DS18B20 is added to read ambient temperature, thermistor returns difference in temp between hot and cold join so you need to know temperature of the cold join to know what is the temp of the tip.
Software upgrades (not done yet)
1. deal with hardware upgrades
2. use PI or PID instead of simple hysteresis to control tip temperature
It will be interesting to see how the different temperature regulation techniques work out. Anyone know how the big players do it?