CH224D Review: USB PD Portable Soldering Iron is Here
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This post was last edited by Unseen on 2022-9-4 23:17
I have been waiting for a long time and have always wanted to make a T12 white light soldering iron, but I have never taken action until Qinheng and eeworld launched the evaluation event of this USB PD chip.
The chip has been in my hands for a long time, and the board has been painted long ago, but I have never soldered it. I also made the shell by hand, and I worked so hard with the file that I felt dizzy and dark. Finally, tonight, when the event ended, I finished the product.
I didn't take any photos during the production process, so I will skip it now. Here are some photos of the materials I bought.
The soldering iron is copied from an open source solution, and the power supply is changed to CH224D. The picture of the motherboard is:
Screen image:
The PD configuration retains the MCU interface, and the voltage can be configured through the MCU to request power from the USB power supply later. However, the T12 soldering iron here is 24V, and the PD application is up to 20V, so there is no need to apply for other voltages.
There is a big BUG in the schematic diagram here. I forgot to draw the MOS driver when I copied the diagram.  I had to manually fly the wires later. Don’t read it if you don’t like it  .
Then draw the 3D structure and simulate the structure to see if there is any interference;
Then it's time to solder the PCB, starting with the screen part:
Then the motherboard:
Here I want to explain the rotary encoder in particular. I used the mouse encoder, referring to the design of the middle button of the mouse. The finished mouse wheel is not easy to make. I searched for a long time but couldn't find it. So, I found a good thing on Taobao:
The small wheel and the matching 2mm steel shaft. The encoder has a hexagonal hole. I originally planned to grind the shaft into a hexagon, but I didn’t expect that this thing was actually over-quenched and very hard. After grinding for a few minutes, there was no movement, so I gave up decisively. I thought of a plan B. I found a 2MM drill bit, and while drilling through the wheel hole, I also enlarged the encoder’s wheel axle, which was just right for clamping and perfectly fixed.
You can see where CH224D is. Yes, it is in the red frame. On such a big board, 224 is just in the corner .
Once again, please ignore the flying wire circuit on the right half of my circuit. Because I forgot to draw it, the components are also temporary transistors. They are super large and very fierce.
After welding, it is time to burn the program. The original program is open source on GitHub, which uses a 0.96-inch OLED with a resolution of 128x64. In order to put it into this profile box, I can only use 128X32, so I need to modify the display code (partial screenshots, complete at the end of the article):
After burning, power on and test OK, ready to play iron:
The rough house I bought looks like this:
Opening the windows and doors looks like this:
I spent the whole afternoon and half a night opening these two small windows, which was very annoying.
I really don't want to grind the end cap anymore,
so I just draw a board and proof it:
In order to save some PCB, I made it into an integrated shell. It's pretty good after assembly, but the copper cladding of the light is not handled well, so I cover it up. I plan to drill a hole directly later;
Make a V cut and break it apart to get two end caps.
I found some minor problems during assembly. My op amp chip was a little too high, and it blocked the encoder wheel. I had to adjust the micro switch a little higher, but I found that the shell was a little difficult to assemble, so I polished the shell again.
Later we still need to optimize the PCB, put the heated MOS driver on it, and then move the op amp to another position.
The last step is to plug in the T12 handle, turn on the power, heat it up, and you’re done!
Below is a demonstration video (because of the problem with the op amp, the encoder is a little stuck when it moves):
VID_20220904_221820
This is the original author's GitHub address: ;
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