yschroeder / solderingiron

An OpenSource Soldering Iron

SolderingIron

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.

Features

• 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

How does it work

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

Temperature measure

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

Solder tip detection

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

References

Links:

• 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.

Datasheets:

• 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

Current State:

• 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