DIY Digital Soldering and Hot Air Rework Station

In this project, I will show you how to build a complete digital soldering and hot-air rework station based on an Atmega microcontroller. The PCB for the project was ordered from JLCPCB.

This station combines a soldering iron controller and a hot-air rework controller into a single compact unit. It provides accurate temperature control, adjustable airflow, real-time temperature monitoring, and independent control of both tools.

The project is designed for electronics hobbyists, repair technicians, and makers who want a professional workstation at a reasonable cost.

All design files, including the schematic, PCB files, Gerber files, firmware, and source code, are available for free.

Electronic Components

1. Atmega microcontroller
2. LCD1602 display
3. LM358 operational amplifier
4. MOC3020 optocoupler
5. TRIAC
6. 7805 voltage regulator
7. Relays
8. Resistors
9. Capacitors
10. Potentiometers
11. Connectors

Tools

1. Soldering iron
2. Multimeter
3. AVR programmer
4. Wire cutters
5. Screwdrivers

After finishing the schematic and PCB design, I generated the Gerber files and ordered the PCB for the project from JLCPCB. You can download all file in the end of intruction.

The boards arrived quickly and the manufacturing quality was excellent. The solder mask alignment was accurate, the silkscreen was clear, and all drilled holes were perfectly positioned. The overall finish looked professional and made assembly much easier.

Once the PCB arrived, I carefully inspected it before starting assembly.

Begin by soldering the smaller components first.

Recommended assembly order:

1. Resistors
2. Diodes
3. IC sockets
4. Small capacitors
5. Connectors
6. Relays
7. Power components

After completing assembly, carefully inspect the board for solder bridges or missing connections.

efore installing the soldering iron and hot-air gun, verify all power supply voltages.

The controller requires an input voltage between 18 volts and 24 volts DC.

Using a multimeter, measure:

1. Output of the 7805 regulator
2. Pin 8 of the LM358
3. Power supply pins of the Atmega microcontroller

All of these points should measure approximately 5 volts.

Do not continue until these voltages are correct.

After confirming the power supply is working properly, upload the firmware to the Atmega microcontroller.

The firmware files are included in the project download package.

Make sure the fuse-bit settings match the values specified in the project documentation. Incorrect fuse settings may prevent the microcontroller from operating correctly.

The Atmega microcontroller runs at a clock frequency of 12 megahertz.

The controller uses four potentiometers.

Potentiometers ranging from 1 kiloohm to 10 kiloohms can be used without any issues.

These controls are used for:

1. Soldering temperature adjustment
2. Hot-air temperature adjustment
3. Airflow adjustment
4. System configuration

The soldering iron used in this project is a common model available on the market.

Specifications:

1. 24 volt heater
2. Thermocouple temperature sensor

To identify the wires, measure resistance between the wire pairs using a multimeter.

The wire pair with the highest resistance is connected to the heater.

The wire pair with the lowest resistance is connected to the thermocouple.

Connect the wires according to the schematic.

The hot-air gun also uses a thermocouple temperature sensor.

Depending on the model, the heating element may be rated for either 110 volts or 220 volts.

Follow the wiring diagram carefully when connecting the hot-air handle to the controller board.

Double-check all wiring before applying power.

After completing all wiring, apply power to the controller.

The LCD display will illuminate and the system will require a few seconds to initialize.

The display provides two status sections:

1. Soldering station status
2. Hot-air station status

The switches and potentiometers are used to control both stations independently.

Turn on the soldering station using its dedicated switch.

Adjust the temperature using the temperature control potentiometer.

The LCD displays:

1. Set temperature on the left
2. Actual temperature in the center

With a 24 volt heater, the soldering iron heats up very quickly.

A status LED on the PCB indicates heater activity. Once the desired temperature is reached, the LED begins blinking to show that temperature regulation is active.

Turn off the soldering station and switch on the hot-air station.

The airflow can be adjusted easily using the airflow control potentiometer.

The hot-air temperature can also be adjusted using its dedicated control.

The controller continuously monitors the thermocouple and regulates the heater to maintain a stable temperature.

⚠️ Important Safety Notice

This project works directly with mains voltage.

The hot-air heater operates from either 110 volt or 220 volt AC power, which can cause serious injury or death if handled improperly.

Always:

1. Disconnect power before servicing
2. Use proper insulation
3. Verify all wiring connections
4. Keep high-voltage areas covered
5. Test the system in a safe environment

Only attempt this project if you are familiar with electrical safety procedures.

The following files are available free of charge:

1. Schematic
2. PCB Layout
3. Gerber Files
4. Firmware
5. Source Code
6. Component List

Download links can be found here

Upload Gerber link here

This project demonstrates how to build a fully functional digital soldering and hot-air rework station using commonly available components and an Atmega microcontroller.

The station offers accurate temperature control, adjustable airflow, real-time monitoring, and independent operation of both tools, making it an excellent addition to any electronics workbench.

I hope you found this project useful. If you build one yourself, feel free to share your results and modifications.