How to Make a DIY Wireless Charger for Your Phone Using Old Electronics


Making your own wireless phone charger at home is a fun electronics project that allows you to repurpose old devices and save money compared to buying a commercial Qi charger.

The basic components needed are:

With a little soldering, you can create a fully functional wireless charger that works with any Qi-compatible smartphone, like recent iPhones and Android devices.

This guide will walk through the entire process step-by-step. I'll explain how wireless charging works, recommend parts to scavenge from old electronics, provide wiring diagrams and installation tips, and show you how to build a slick enclosure for your DIY charger.

By the end, you'll have the knowledge to build custom wireless chargers tailored to your needs. Let's get started!

How Wireless Charging Works

Wireless chargers use an electromagnetic field to transmit energy between two coils:

This wireless energy transfer occurs based on the principles of inductive coupling between the transmitter and receiver coils.

Electricity flowing into the transmitter coil creates a magnetic field, which induces a current in the receiver coil. Your smartphone has a built-in receiver coil to convert this current back into charge for the battery.

As long as the smartphone is properly aligned with the transmitter coil, this charging happens automatically without wires!

Key point: Wireless charging relies on inductive coupling between transmitter and receiver coils to send power magnetically over short distances.

Choosing Transmitter and Receiver Coils

The two most important components for building a wireless charger are the transmitter and receiver coils:

Transmitter Coil

The transmitter coil must be able to carry a high current to generate a strong magnetic field. Some options are:

Aim for 5-15 turns in the coil and a diameter of 8-12 cm. More turns yields higher inductance but requires thicker wire.

Receiver Coil

The receiver coil should be Qi compatible so that the magnetic field induces a current that your smartphone recognizes. Good sources are:

Try to find a coil with similar 8-12 cm diameter as the transmitter. The coil thickness is less important than diameter.

Note: Matching the diameters helps maximize energy transfer between the coils.

Scavenging Components from Old Electronics

Many parts needed for a DIY wireless charger can be salvaged from old electronics headed for the landfill. Great sources to scavenge from include:

Always discharge capacitors and watch for high voltages when taking apart power supplies.

Specific components to look for:

Saving usable parts keeps them out of landfills and helps the environment!

Wiring Up the Circuits

With the main components gathered, it's time to wire up the circuits that make the wireless charger function:

Transmitter Circuit

The transmitter circuit powers the coil that generates the magnetic charging field. It consists of:

Follow the wiring diagram below:

5V | Power |
| Supply |
AC +--------+
AC | Bridge |
in | Rectifier | DC out
| |
+---------+ +---+
| | | |
Transmitter | | T |
Coil | | r |
+---------+ +---+
(To phone receiver)


Note the bridge rectifier is needed to convert AC wall power into DC that the coil requires.

Receiver Circuit

The receiver circuit takes the induced power from the transmitter coil and charges your phone's battery:

Follow this simple diagram:

AC | Coil | DC
in | | out
| |
| Regulator|
| |
| |
| Phone |
| |

The voltage regulator is key to provide the 5V/1A output that smartphones are designed to charge at.

Putting It All Together

When the full transmitter and receiver circuits are combined, the end-to-end wireless charging system looks like:

+------------+ +-----------------+ +---------------------+
| |AC | | | |
| Power +------> Bridge Rectifier +------> Coil |
| Supply | | | | |
+------------+ +-------+---------+ +---------+-----------+
| |
| |
+--------+--------+ +-------+--------+
| | | |
+---+ T| | |
| | r| | |
Coil | | a| | |
| | n| +---+ |
+---+ s| | | +---------+
| R | | | Phone |
| e | | | |
| g | +---+ |
| u | |
| l | |
| a | |
| t | |
| o | |
| r | |
+---+ |
| |
| USB |
| |


Follow this diagram, test the connections thoroughly, and your DIY wireless charger should function!

Building an Enclosure

With the electronics complete, the last step is building an enclosure to finish off your wireless charger:

With a nice enclosure, you'll have a slick looking wireless charger that hides away the inner DIY electronics.

Start Building Your Own Today!

Constructing your own wireless phone charger is a satisfying electronics project that recycles old devices and saves money.

This guide covers the core concepts and components so that you can build custom Qi chargers tailored to your needs.

The basic process is:

  1. Gather transmitter and receiver coils plus support electronics by salvaging old devices.

  2. Assemble the transmitter and receiver circuits following the wiring diagrams.

  3. Install the electronics into an enclosure, aligning the coils carefully.

  4. Decorate your enclosure and start wirelessly charging phones!

Don't throw out that old computer power supply or broken wireless charger just yet. With a bit of DIY spirit, you can reuse the parts to make new devices instead of adding more e-waste.

So scavenge those components and start building your own wireless phone charger today!