Making a Wireless Power Supply for the UNIHIKER Single Board Computer

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The Unihiker single-board computer as a powerful board serves a multitude of purposes It can be applied in scenarios such as IoT projects, scientific experiments, and robot control. To introduce more playful and elegant interactions in these scenarios, we could consider creating a wireless magnetic charging method. Imagine the grace of simply snapping a Unihiker onto a wireless charger. To bring this concept to realization, I've crafted the first version of a desktop wireless charger. This device is designed to provide wireless power to the Unihiker, all in the pursuit of elegance.


Part One: The Principle of Wireless Power Supply


Wireless power supply allows the transfer of electrical energy to a receiver through air, paper, or even plastic casings. The technology we are utilizing here is magnetic resonance coupling, which has the advantage of enabling the transfer of energy wirelessly, without the need for direct contact or wired connections. It can be applied in scenarios that require wireless power, such as wireless charging pads, electric vehicle charging, and more. However, due to the attenuation of the magnetic field, the transmission distance is relatively short and the efficiency is comparatively lower.

(Resource: Cheah WC, Watson SA, Lennox B. Limitations of wireless power transfer technologies for mobile robots. Wireless Power Transfer. 2019;6(2):175-189. doi:10.1017/wpt.2019.8)


Magnetic resonance coupling technology transfers energy from the transmitter to the receiver through magnetic field coupling. The principle behind it is the use of magnetic field coupling between two resonant cavities to achieve the transfer of energy. This technology mainly includes two components: the transmitter and the receiver. The transmitter typically consists of a transmitting cavity and a power source, while the receiver consists of a receiving cavity and a load.






Part Two: Preparing the Hardware 


The Unihiker, as a single board microcomputer capable of Python programming and IoT control, means that it can be easily accessed as long as it is on the same network. It integrates an LCD color screen, GPIO sensor interfaces, WiFi, and Bluetooth capabilities, which facilitate connections and interactions with other devices. Therefore, wireless power supply will not interfere with our data transmission and control with the Unihiker.


On the Unihiker, not only can you use the interfaces that have been lead out, but you can also use the reserved metal contact points for functional expansion. For instance, by soldering the positive and negative terminals to a receiving coil, you can enable wireless power supply for the Unihiker.


1 Wireless Charging Module 5V/2A
1 Type-C Extension Cable
4 M3 Magnetic Screw

Hardware Connection:


The following connections for the transmitter and receiver must be soldered separately: 

· Before soldering, ensure the positive and negative terminals are correctly connected, which can be verified using a multimeter.

· Ensure the receiving coil's output voltage is between 4.8v and 5.3v with a multimeter before welding.



· Before assembly, ensure that the back of the receiver's PCB is covered with insulating tape to prevent short circuits.

3D Printing:




Download: https://www.thingiverse.com/thing:6414463


NOTE: You may need to fine-tune the model's coil zone to match your coil size.

Assembly Process:


Step1: Pass the soldered transmitter coil's Type-C extension cable through in the direction indicated by the arrows.


Step 2: Install the transmitter coil.


Step 3: Install the screws.


Step 4: Install the magnetic screws for the transmitter and secure them from the back with screws.


Step 5: Install the receiver's casing and coil as shown in the diagram below.


Step 6: Position the inductor to align with the holes in the casing and install the magnetic screws.


This wireless charger provides a more innovative and elegant power supply method for the Unihiker. Whether it involves attaching a portable wireless power bank or adding an internal battery for wireless charging, there is ample room for imagination. We can look forward to developing more elegant and interesting uses for the Unihiker in the next project.

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