DIY Wireless Mobile Phone Charger

By Mithru Vigneshwara, Creative Technologist

Shopping List

1. 12V wall adapter
http://www.seeedstudio.com/depot/Wall-Adapter-Powe...

2. Wireless Charging Module
http://www.seeedstudio.com/depot/Wireless-Charging...

3. USB A Female
http://www.seeedstudio.com/depot/index.php?main_pa...

4. 3mm LED (optional)
http://www.seeedstudio.com/depot/3mm-LED-Red-100-P...

5. Resistor (optional)
http://www.seeedstudio.com/depot/RESK-Resistor-Kit...

In the case of the module prescribed in

this document, the receiver is the one with the relatively longer PCB. The receiver unit, is the one that connects to the device that needs power. It receives power wirelessly from the transmitter unit.

The transmitter in this case needs a power supply of 12V.

Solder the transmitter to the 12V wall adapter. You may either cut and strip the end of the wall adapter, and solder it directly to the transmitter, or procure and solder a female connecter to the transmitter. Check the polarity of the 12V adapter cable before soldering.

Image: Transmitter unit directly soldered to wall adapter’s cables

Now that the transmitter is ready, test it 3by powering it up and hovering the receiver unit connected to a voltmeter over it. The voltmeter should show 5V input when the receiver’s ring is aligned with the transmitters ring.

Image: Receiver when wireless transmitter (under the white surface) is turned off

The receiver can now be connected to any device that takes up to 5V input. Most devices that use a USB cable to charge (like phones and tablets) use voltages of this range. Since it’s relatively complicated to solder this directly on the devices themselves, that section will probably be covered in a different tutorial. In this case we will be soldering a female USB A connector to the receiver and plug a phone into it via USB to test.

Solder the receiver to the USB A connector. The first and last pins on the USB are +5V and ground. To figure out which of the two is ground, use a multimeter and check connectivity with the exterior metal and one of the pins. The exterior metallic part is also grounded.

Once done, check if it all works with a USB-powered device. Your could also add an indicator light to check if power is being transmitted as shown below, but do be aware of the current draw by the LED that will steal power that would otherwise go into charging the USB device.

Image 1: In the above picture, the receiver is connected to an LED and a USB female. The LED is powered wirelessly (transmitter is powered and placed under the white surface)

Image 2: Picture shows phone charging when connected to receiver unit (transmitter is powered and placed under the white surface).