This inductive charging set comes with a square - shaped transmitter board that has two chips on it. It requires a 9V power supply. The longer board serves as the output and can be connected to the part of your project that needs power. Inductive charging allows you to power a device without a direct wire connection. You've probably seen this in rechargeable electric toothbrushes, where you simply place the toothbrush in the holder to recharge. This charger works by splitting a power transformer in half. An AC waveform is generated in one part and couples into the second coil. It's a basic charger set that works well, providing a 3.3V DC output when the input is powered with 9V - 12V DC. You can draw up to 500mA when the coils are 2 - 3 mm apart. If you need 100 - 200mA, the coils can be up to 7mm apart. For a 10mA draw, they can be up to half an inch (12.5mm) apart. You can use any non - ferrous and non - conductive material like air, wood, leather, plastic, paper, or glass between the coils without affecting the distance or efficiency. However, for the best power transfer, the coils should be fairly co - axial, parallel, and have their circles lined up. Since it's an air - core transformer, it's not very efficient, with only about 40% of the energy reaching the other end. But it's great for low - power or charging projects. There's a quiescent current of about 70mA all the time, even when the other coil is far away. These are basic modules, perhaps for low - cost toys. There are no datasheets or specifications available, but advanced users can change the feedback resistor on the output side (using 0603 SMT resistors) to adjust the output value.
Using this inductive charging set is easy. First, connect the square transmitter board to a 9V power supply. Then, connect the longer output board to the part of your project that needs power. Place the two coils close to each other. If you need a high current, keep the coils 2 - 3 mm apart. For lower currents, you can increase the distance. You can put materials like wood or plastic between the coils. Make sure the coils are parallel and their circles line up for the best power transfer. Remember, this charger is not very efficient, so expect some energy loss. There's always a 70mA quiescent current. As for maintenance, keep the boards clean and dry. If you're an advanced user and want to change the output value, you can solder different values of feedback resistors on the output board.
