I've been a Nintendo fan since the days of GameBoy, so I was very excited when I got the 3DS as well.
Imagine my joy when I found out there's no AC adapter included, so I couldn't play anything until the holidays were over and the stores open again. I've had to improvise with this abomination so that I could kinda charge it.
Looking back at historical data, Nintendo only made about 5 billion in revenue at the launch of the New 3DS.
I'm sure we can all agree that including a charger that costs about a dollar to produce could very well bankrupt a company that's making only a few billions per year...
Anyway, I went a step further with my 3D printer and designed a fully functional charging dock.
Continue reading to find out how it works and how easy it is to make one yourself.
I'll begin by measuring the 3DS and then creating a sketch in Fusion360.
I don't care about the details, a simple box will do just fine. It's more important that the dimensions and button placements are correct.
Next, a simple base around the 3DS, and don't forget to fillet all the corners.
The most important part is the charger itself. The New 3DS has exposed charging contacts on the bottom.
I went through a lot of different designs and ideas; the charger had to be very small to fit the contacts and I only wanted to use materials that most people can find around the house.
In the end, I came up with this.
There are two pins on top for holding the wires.
The entire thing is then pushed upward with a spring, ensuring a good contact with the 3DS.
And this is what the inside of the dock looks like. It's designed so that you can print everything without using any supports.
As for the spring, find an old pen and take one from there. The slot has a slope so that springs of different sizes can all fit inside.
The holes are for standard jumper wires that you can find with any breadboard or Arduino kit, but they have to be solid.
If you don't have any wires like that, you can improvise by cutting away an LED or a resistor.
First, insert the wire into the hole and bend it around the corner. Then flip it around and push the long end of the wire to the other side.
Keep pushing it in and make sure the short end goes inside the hole as well.
Looking at the top, the wires should create a curve like this. This can be quite tricky. If it's too wide, it won't fit inside the small contact openings on the 3DS. You might also have to bend it to get a more V shape instead of U. This is simply something you'll have to play around until you get a reliable connection.
Use small pliers if you have to reshape it for a better fit.
With that done, let's talk about the actual charging.
Because this is Nintendo, the charging cable is basically a standard mini USB plug, but changed just enough that it doesn't fit and you have to buy a dedicated one.
We don't actually need the special plug, but you will need a USB cable that you're willing to cut.
You only need red and black wires so you can cut away the others.
Before we connect the wires, we have to talk about voltages. 3DS charges at 4.6V while the standard voltage for USB is 5V. So what can you do?
Well, you can do nothing and simply use 5V for charging. Devices like the 3DS are designed with a safety margin and there's no risk with charging it at 5V. In fact, every 3DS cable that you can buy has a standard USB plug and therefore charges at 5V.
Having said that, you can lower the voltage down to 4,6V if you want to complicate things.
You might think it's ok to simply attach a resistor, but that won't work because the charging load isn't constant. A better option is to use either a buck converter or a low-dropout regulator.
The issue with buck converters is that most aren't capable of achieving such a small voltage difference. For example, a cheap one like this can only go up to 4,5V and that's already pushing it.
Low dropout regulators don't suffer from this issue, but they can produce a lot of heat. Quick calculations for a typical LDO are showing around 55'C, which is getting very close to what PLA can handle. You should definitely keep it out of contact with the surface or use a heat sink.
But like I've said, you really shouldn't bother and just use the standard 5V.
Looking at it straight on, the right wire is positive, so solder it with the red wire from the USB cable.
You'll find a small chamber on the bottom where you can tuck everything inside. There's also a small cover available if you want to completely close it.
The stiffness of the spring is very important. If the spring is too strong, it will tilt the 3DS and lose contact. If it's not strong enough, it won't push against the charging contacts. You will have to tinker with the spring until you get a good fit. I did it by cutting away one loop at a time, putting the spring back in and trying if it works. Keep doing it until you get a reliable contact.
As a bonus, I've designed a set of swappable plates.
For best effect, you should print them in multiple colors. Don't worry, you can do this with any printer, because you'll simply be changing filament at certain heights.
If you want to make your own design or learn more about the process, I've already made a separate video on how to create models and change colors.
Of course I'm including a blank plate as well to make it easier to design new ones. Be sure to share them with others.