Create an inexpensive and simple DIY digital welding station to automate it through the PID system. Simply, the automatic electronic control system of the welding station will continue to adjust the "dimming knob" for you. When the system detects that the temperature of the soldering iron is lower than the set temperature, the system will increase the power required to generate heat on the soldering iron. When the iron temperature is higher than the set temperature, the iron will be powered off, resulting in a decrease in temperature. The system can complete this process very quickly, and constantly open and close the heating element of the iron to keep the constant temperature of the soldering iron head.
Parts:
HAKKO 907 handle (clon)
Arduino nano
Step converter (MP2303 of D-Sun)
5-pin DIN female connector
DC jack (2.1mm)
24V 3A power
16x2 I2C LCD screen
LM358 operational amplifier IC
IRLZ44N MOSFET (IRLB4132)
1N4007 diode
470uf 25V electrolytic capacitor
470Ω1 / 4W resistance
2.7kΩ1 / 4W resistance
3.3kΩ1 / 4W resistance
10kΩ1 / 4W resistance
10K potentiometer
Note: The video schematic and the IRFZ44N tag on the PCB is wrong. Using IRLZ44N, it is a logical level version of IRFZ44N.
Recommended MOSFET specification:
Logic level N-channel MOSFET-logic level MOSFET can be directly connected to logical pins (and digital pins). Since the saturated gate voltage is lower than the voltage of the conventional MOSFET, the gate of the logic level MOSFET to the source of the source of 5V or 3.3V (Vgs).
VDS is at least 30V (or higher) - this is the voltage limit of MOSFET, working at 24V, VGS should be 24V, but the usual practice is to increase some stability. Most MOSFETs have typical VGSs 30V. As long as other specifications are within this range, it will not cause harm to use MOSFETs with higher VGS voltage.
When RDS (ON) is 0.022 Ω (22mΩ), the lower the RDS (ON), i.e., when saturated, the lower the resistance formed on the drain of the MOSFET and the source lead. To simplify all operations, the lower the RDS (ON), the lower the temperature of the MOSFET. If your RDS (ON) is high, the MOSFET will run in a heating state because the power is dissipated by its tiny resistance characteristics even if the MOSFET is in turn on.
The ID is at least 3A or higher (I suggest it above 20A) - this is the maximum current of the MOSFET can handle.
Schematic:
The project uses a simple logic level N-channel MOSFET as a PWM-controlled switching device that is used for the digital switch powered by the heating element. That is used to enlarge or amplify the minute voltage combined with or amplify the combination of the voltage sensitive resistance. The 10K potentiometer is used as a variable temperature control knob, and the LED displays whether the heating element is in an active state in the project.
PCB:
Calibrate BUCK converter:
Since most Arduino Nano clone products are most at 15V voltage, the AMS1117 5V regulator will not burn the AMS1117 5V regulator, while the heating element needs 24V to work best, so I Buck converter is used in the project. The pressure difference of the AMS1117 5V regulator found in Arduino Nano cloning products is 1.5V, that is, the input voltage of the VIN pin of Arduino Nano must be 6.5V (5V + 1.5V).
step:
Set the power supply to 24V
Connect the power to the input of the buck converter
Use a multimeter to monitor the output voltage of the buck converter
Adjust the fine-tuning resistor until the output voltage of 6.5V is obtained
Better stability can be obtained using 7V.
Circuit assembly:
Shell 3D printing:
3D printer settings:
Print on CREALITY CR-10
0.3 mm layer
0.5mm nozzle
30% filled
No need to support
Be
3D print file (SolidWorks and STL):
https://drive.google.com/drive/folders/1xxkatawj18doj8kbdomozoch-auhw_hk
Install external components:
The LCD, 10K potentiometer, DC jack, and drive board are fixed in place. The DIN connector and LED adhesive to the housing.
HAKKO 907 connector:
HAKKO handle's proprietary 5-pin DIN connector, the third pin is just grounding.
Connect external components:
Add a fuse to the DC jack and the assembled drive board to provide additional protection.
Programming:
step:
Connect Arduino to your computer
Download procedure
If necessary, please adjust it
Set a standardized value for the HAKKO 907 handle
Make sure Wire.h and LiquidCrystal_i2c.h libraries are installed
Tool. 1882. Development board. 1882. Select Arduino nano
Tool > Port. 1882. Select the port to connect Arduino
Upload sketch / procedure
Mode of work:
When the system detects that the temperature of the soldering iron is lower than the set temperature, the system will increase the power required to generate heat on the soldering iron. When the iron temperature is higher than the set temperature, the iron will be powered off, resulting in a decrease in temperature. The system can complete this process very quickly and turn off the heating elements of the iron to keep the heating of the iron head.
Arduino code (v1.0): https://drive.google.com/drive/folders/1fzx1agwwvwwpm4xlkmnghrr_i4lysarx
Adjust the LCD contrast and potentiometer to add the knob:
If you are not familiar with Arduinos and 16x2 LCD, you must adjust the LCD contrast fine tuning resistor to make it normally displayed. After all settings are completed, it can eventually add a plastic knob for the potentiometer to perform temperature control.
Turn off the chassis and turn on the power:
It is determined that the welded table has been calibrated correctly, and the rear panel can be turned off and tightened. Battery or AC-DC power can be used. If you want to get the best performance, use a 24V 3A power. A laptop charger can also be used for soldering station using a SMPS power supply of a metal housing. Nominal laptop chargers typically use, but the warm-up time of the iron may reach 37s.
Video tutorial:
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