Control and drive circuit for Weller RT tips

When I would like to use a professional soldering iron for assembling circuit with smd components, then the one of best solutions is to purchase a Weller soldering station with RT type tips. The problem is, that it is very expensive. Good news, that there are some independent developments to substitute the original station to much cheaper one.

I think this project is very good choise for this issue. I made it in three different versions:
- The first is the original version from the 'kair.us'.
- Second has little modifications e.g. the display has become common anode controlled (the original is common segment controlled). I also had to change the firmware to make it work perfectly.
- The third is same as original, but I can use some different components in the same positions: the board can accept three different 5V LDOs, and can also accept SSOP-28 package microcontroller instead of SOP-28 (the second version has this feature too).

Finally I planned a new PCB, which has an 3.5 jack socket. This solution is more confortable for a 'poor' device.

And I recompiled the firmware with two little modifications: 1. the default state is the 'standby' after the power on and 2. changed the rotary encoder function, where the left turn decreases, the right turn increases the temperature settings (originally these were reversed).

(The soldering iron stand is a magnetic paperclip holder from the office.)