Creating a Wireless Charging Stand for the Essential Phone: Custom PCB and 3D Printing
The PH1, first iteration for a brand-new phone company at the time named Essential, was a first-of-its-kind. Featuring the first borderless display back in 2017 with his waterdrop notch, titanium sides, and a ceramic back, it was and still is a stunning piece of technology.
Style aside, this phone had another promise: extended functionalities via modules. Making use of two pins on the back of the phone for power, and wireless connectivity for data, the Essential Phone came out with only one accessory, a 360 Camera.
But while an Essential Dock what long-promised, it never came out to the public. The phone being incompatible with Qi wireless charging due to its ceramic back, there is only one option left for getting it to charge in a more convenient manner than with a USB-C cable: DIY.
TL;DR + Prefer things in motion? 📹 YouTube Video
0. User Requirements
Spending most of my days at my desk, like many people, I like to have my phone charging to when I leave, I actually have enough battery for everything and anything. Having it in a standing position also allows for quick reading of notifications. Finally, for some use cases like quick online banking, access to the fingerprint is mandatory, so let’s try to keep it in reach.
Formally, let’s write the following requirements. The phone should be:
- Charging without having to plug a cable;
- Standing so information and notifications are delivered seamlessly;
- Leaving the fingerprint scanner accessible.
1. The Prototype: our own Printed Circuit Board
1.1 Reverse-engineering the accessory pins
From the Essential specifications, one can learn that communications with accessories such as the 360 Camera are handled by a system in which:
- data flows from the phone to accessories wirelessly;
- power is drawn from the pins themselves by the accessories.
However, it turns out these power pins are functioning both ways: by applying a 5V current on them, the phone shows immediately wireless charging graphics and starts charging, as pictured below.
1.2 Pogo-pins and USB-C for convenience: Autodesk Eagle
While holding a cable to the pins it totally fine the previous picture and some subsequent testing, we need to find some way to properly connect these pins to our intended product.
It turns out that in electronics, spring-enabled conductive bars are used to easily test circuits, and answer the cute name of “pogo-pins.” All credits go to my fellow Essentialist u/Untribium for finding this solution.
The aim is to have these mounted on a solid board, and connected to a source of power. And while the Essential Phone isn’t the latest phone in town, it featured a modern USB-C port and came with the corresponding cable. Let’s be consistent with that by using the same port and therefore allow the OEM cable to be used for our wireless charging stand.
And in the end, the easy answer to hold and connect both the pogo-pins and the USB-C port is a Printed Circuit Board. Technology is evolving really fast, and designing custom PCBs is no more reserved for highly-skilled electrical engineers. Let’s hop onto Autodesk Eagle, a free-as-in-free-lunch cross-platform PCB design tool to do just that!
You can find all the source files that you can freely edit to get you started in the Thingiverse post (alternative Google Drive link).
There is one topic on which we can expand a little: these two resistors in the middle of our simple board. When we did the first test with the brutalized USB cable, we only had two wires. What is the deal here? Compatibility! USB-C cables are using a new protocol called Power Delivery in order to deliver, well, power. For the charger to know how much power to actually send, this protocol is using a so-called C-C channel (additional wires), on which the receiver specifies the maximum amount of power it should receive. By putting two 5.1K resistors on that channel, we explicitly require currents lower than 3A (ie. 15W on 5V connections).
1.3 Manufacturing on JLCPCB
Designing is one thing, but how do one Print these ugly Circuit Boards, uh?
Well, this is evolving too. There was a time when minimal orders were 20,000 pieces and prices for small-batch manufacturing to the roof. But automation found a solution to that, and today’s leader for Printing-as-a-Service is a Chinese company named JLCPCB. For $2, you can get 5 boards printed and shipped to you in a matter of days.
On Eagle, you have to click on Manufacturing > CAM… > Process Job. Then you can head to jlpcb.com and upload the .zip file just generated containing your Gerber files.
The order process is incredibly simple, and you can then follow each step of the manufacturing, and wait for the 5 boards to reach your mailbox. Amazing stuff.
1.4 Soldering and final tests
For the parts, we ordered for 5 boards at two different places:
- The 5.1K resistors and 6-pin USB-C ports on JLCPCB’s sister website;
- The PGTH400 pogo-pins on Aliexpress.
Now that everything is in place, we can proceed to the soldering, which is a bit tedious for the port but totally doable at home without proper experience and inexpensive $10 irons.
The process is:
- soldering the two resistors on each side
- soldering the 6 pins of the USB-C port to the board
- soldering the two pogo pins from the back of the board
We can now test our custom board. Yay!
2. Creating the Stand: 3D Printing
2.1 Objectives
Now that we have solid foundations for the electrical wiring, let’s focus on designing a great stand. In addition to our global User Requirements, let’s have the following design objectives. Let’s aim for:
- a low-profile design;
- a robust good connection with the pins on the board.
While the first one is a matter of taste and CAD skills, the second one can be expanded a bit. In order to keep the accessories such as the 360 Camera in place, Essential added (at least) 2 magnets next to the pins. Let’s make use of them in the design of the stand to allow for the phone to stay well-aligned on its own (again all credits to u/Untribium).
2.2 Design
The great thing about Autodesk Eagle as a PCB design tool is its integration with Autodesk Fusion 360, a free-for-personal use cloud CAD platform. In three clicks, the board is exported as a 3D model right in a Fusion project, from which we can design thereafter.
We settled on the following 1-part design for our wireless charging stand.
The CAD source files are available on this public Fusion project link.
2.3 Print!
After simple slicing with Ultimaker Cura, we obtain the following printable blueprint, with the removable supports option enabled.
The print took 7h30 to complete on a Creality Ender 3 printer, using PLA as material (the simplest and cleanest).
3. Going Further: a Product?
Reaching this point feels really good. We completed the realization of a full-blown prototype, that fulfills each and every one of our User Requirements. Still, could we go a bit further and think about it from a product perspective?
As a member of the very active and dedicated Essential community, the need for a wireless charger has been voiced for a long time. The reasons for this are multiple, from the convenience standpoint of a quick way of charging to the specific use case of listening to USB-C audio while charging.
However, as of now the phone is officially unsupported, and the community is transitioning to new devices, so we would be definitely late to the game. Nonetheless, building a very affordable solution could work, and we clearly see that aiming at prices like $9.99 would totally be doable using a cheap plastic casing. It would be also very interesting to go the high-quality side and build a fancy Aluminium casing, that would match with the premium Titanium+Ceramic materials of our beloved PH1.
My fellow Essentialist u/Untribium is manually producing and selling multiple versions of a wireless charger using the same approach, that you can check out at https://www.untribium.com/.
Wrapping Up
- Using Autodesk Eagle to create a custom circuit board
- Sync with Autodesk Fusion to design a 3D-printable stand/casing
