Idea for an OpenSource Soldering Iron

This project is just another avr based soldering iron. Since professional equipment is quite pricy and not very complicated this projects takes a good, changeable soldering iron tip like the Weller RT1 and provides all the electronics behind that.

• open hardware (schematic and layout made in Eagle 7.2 freeware license)
• open firmware written in C (not ready to use right now)
• fast heatup
• saving and restoring temperature to and from EEPROM
• high-precision op-amp for temperature measurement
• safety measures against overheating and controller crashes
• automatic temperature control (pid controller)
• different temperature scales available (recompiling necessary)
• solder tip rest detection via hall sensor (optional)
• almost all parts are available from the Seeedstudio Open Parts Library

• 5V for logic
• 12V for soldering iron
• ATmega328p controlled

The thermo-voltage signal is amplified by an op-amp with a gain g = 1 + R1/R2 = 1 + 51k/100 = 511 this signal is converted by ADC0 using Vcc=5V as voltage reference

Solved by a hall sensor connected to ADC2. This sensor is powered by 5V

• arduino uno shield
  • Forum discussion + group order coordination Thema: DIY SMD - Lötstation Ersatz für (WELLER)
• original Weller cable
• unfinished project Custom Weller WSM 1 style controller for RT series tips
• Thermoelement im Weller WMRP.

• power MOSFET IRF7424
• Voltage regulator REG1117
• uC ATmega328P
• Quad OP-Amp LM324D
• Single OP-Amp OPA336u
• Solder Tip Weller RT1
• Solder Tip detector Hallsensor unipolar

• hardware version 1.2 is almost ready to be produced
• optimized bill of materials by reducing unnecessary components
• PCB measures 5cm x 5cm
• individual 7-segment displays in use (broader availability)
• I2C is now unused and can be used for additional hardware