I have been attracted by a compact instrument, I like to buy electronic kits and make small and beautiful equipment.
A few years ago, I bought a regulated power supply unit (PSU), which has an interesting function that can change the current intensity other than the voltage.
The project will focus on how to build a regulated power supply unit using a regulator power unit (PSU).
Step 1: Demolition and adaptation
As the first thing, I tested my device, and then I started to imagine the best way to build some things. As you can see, I connect it to my recent battery pack with ten 18650 batteries. Since the lithium ion charging treasure is very powerful, I want to take advantage of it. I also want to put the equipment into the battery pack, but the space is not enough. Thus, the regulator PSU can be powered by any battery or wall plug power supply.
Unscrew four screws, separate the top plate and the bottom plate, which also act as a connector.
Step 2: Details Adjustment
If you need to regulate voltage and current, those small potentiometers are inconvenient, although they are very accurate, they need a lot of circles to move from low to high. So I decided to replace them with several larger jars. I have to choose between many types and shapes, I chose two classic jars.
Step 3: Welding external control
The value of the resistor is the same, 10 kohm, the central pin of the resistor must also be soldered in the center position, in order to find the correct position of the other two pins, you can try it, but if you look at the original pot, you can see one The chart and the pin corresponding to clockwise. I also added a 2.1MM DC power outlet, and the wire was connected to the positive and negative DC-IN pads, but then I inserted a universal switch on the front pole line. As an output, I used two (red and black) banana plug panel sockets.
Step 4: Design and 3D printing
I think the design is the most interesting part, because you can completely choose any details, from the size to the knob position, from the color to the grid shape. After deciding which components used, I spent one or two hours of drawing, measured with caliper, calculating the minimum space required inside the housing.
I don't deepen the use of Rhinoceros to draw 3D processes, because I have explained some basic knowledge in other tutorials. You can also use OpenScad, which allows you to develop parameterized 3D models. Get a very good 3D model, I am here, I will export it to .stl, then load it into CURA, where I saved G code to my small 3D printer. The result of the first trial is perfect, but I added some improvements in the final version of the file.
Minipsu02.stl
Step 5: First test
After 5 hours of printing, I can't wait to try this case. So I put all the parts, fortunately, I didn't find obstacles.
Step 6: Weight settings
When you pick up a tool, a gadget, a general object, the weight will pass a sense of toughness and quality. This is why I decided to use the thick iron plate as the bottom. I drilled four small holes for the screws, and left two big holes in addition to rust. I posted a thick tape in the inner surface to avoid short circuit.
Step 7: Cooling
I think this device can't keep 5A (maximum load), especially for a long time, no heating too much and closed. So I added a small motor and a very small fan in the design, as long as the PSU is turned on, it will work. The motor operating voltage is only 3V, consumes a few millians, and produces some noise. If I have a sufficiently small brushless motor, I will use it because the noise is lower, longer life.
The little fan is 3D printing. I made a small mistake in the design, I can't use all the space, but I don't want to do this again. I am attached to the fan .stl file.
Fan .stl
Step 8: Circuit Design
In order to power the motor, I use a voltage regulator that can only keep 100 mA load, but it is ideal for this purpose. Then I added a 40 ohm resistor to reduce the speed and noise. You can see the black small 3.3V regulator and the resistance soldered at the output, from the main switch, and the negative electrode is from any where you want, the resistance welded on the red line leading to the motor. It is not a lot of space, I am hard to weld everything in place. In the final version of the 3D model, I moved a pair of millimeters to the left side to leave more space for the motor.
I use crude copper wire and two screws to fix the motor, which is a simple but effective method.
Step 9: Tag label
I wrote some useful information about the top and positive parts. I also wrote information about the load and socket polarity on the bottom information. This information is not fully accurate, and they should be "DC IN 6-35 V", 30V is the largest output. I know that the style is also very ugly, but you can make a template or simply use better calligraphy.
Step 10: Show filters
A red LED display like this is almost can't see in the sun, and they are usually covered by dark red transparent boards. I tried different solutions, I chose an orange-yellow organic glass. The monitor now still can't see it in strong light, but it is better than before, but the effect of light scattering on the border is forgiveness. Surprising.
I use a simple iron saw to cut a small plate, then I polished it around the sandpaper, and use a thinner triangular piano once again, I use brass polished products to polish all four sides.
Step 11: Enjoy the results
Datual! Mini regulated power is ready!
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