A soldering station is probably one of the first things a maker should invest in. The ability to build your own equipment is what quilifies you as a maker. Building my own soldering iron controller was in my To-Do list for months. I found a cheap chinese clone of the Hakko 907 iron and discovered that there are a lot of diy controllers for this iron out there.
I used an Arduino pro mini compatible board to keep it simple and open source so other makers could build it and improve it. I discovered Kuro's soldering station and decided to build my controller based on his with a few additions. I used his firmware to control the temperature with PID. Also I use an RGB LED and a bar graph on the screen to visualize the tip temperature. The extra buttons on my board are used to control the screen brightness and enable/disable rounded temperature. The brightness value and the P, I, D parameters are stored in the EEPROM.
I have made a few changes in the firmware. Some of them require changes or additions on the PCB and inside the iron’s handle.
– I added a buzzer that beeps on every button press and when the station enters sleep mode or turns off. I soldered it directly on pin 13 of the arduino pro mini.
– A lot of people were asking for sleep mode. I added a function that turns off the heater after a predefined time period but that wasn’t enough. I soldered a reed swith inside the iron’s handle. It’s connected between Analog 4 (Digital 18) and ground pins of the pro mini. I added a magnet on my base. When I leave the iron on the base, the reed switch closes and it enters sleep mode after 30″ (target temperature: 150°C). After 5′ in sleep mode the heater turns off.
-For safety reasons the heater turns off if something goes wrong and the temp exceeds the MAX temp + 30°C for more than 5″.
-I added a new progress bar on the screen and a new temp icon. Also the duty cycle is shown on the screen.
-As you can see on the video below there is a boot screen that goes away when I put the iron on the base. That way I always remember to put it on the base before turning it on for the first time and prevent entering sleep mode before reaching the target temperature.
I still have to calibrate it by measuring the actual temperature of the tip with an external device but that would be as easy as changing two parameters.
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