Make your own USB mobile phone charger

　　Now is the information age. Mobile phones and computers can't be less than one. For friends who often use mobile phones, the biggest pain is the phone's standby problem. Although the standby time of mobile phones is constantly extending, some can reach more than a week, but for some friends. Still often forget to charge. If the phone is out of power, things will go wrong. When you see the power socket, you remember that the charger is missing. It is even more depressed. This is especially true when going out on the train. Not even a power outlet. Not to mention charging. Well known. The USB interface can provide a voltage of 5V and a current of 500~2000mA. If this USB interface is used to provide a charging voltage for the mobile phone, will it not be able to solve the problem of mobile phone charging? This kind of USB interface charger has also appeared in the market now. However, there are not many types of these USB interface chargers in the market, and they cannot cope with all kinds of mobile phones. In fact, this kind of USB interface chargers are easy to make. I will take my own mobile phone as an example to explain how to make it. USB interface charger method.

　　The author's mobile phone is Huawei, and there is a type-c charging jack on the bottom of the mobile phone. The mobile phone uses 3.6V lithium battery, and the rated output voltage marked on the charger is 3.7V, 355mA. The voltage of the USB interface is 5V, and the maximum output current is 500mA. The voltage and current provided are greater than the output of the charger, which provides possible conditions for making a USB charger. The 5V voltage is slightly higher than the 3.7V voltage of the charger, but according to actual measurement. The output voltage of the charger is much higher than 3.7V, even higher than 5V, reaching about 7V. I don’t know how to do it. Think about the voltage of about 7V and the mobile phone can withstand it, not to mention the 5V voltage of the USB interface. Therefore, there is no need to install diodes or resistors and other step-down components between the USB interface and the mobile phone.

　　What is the inside of the charger? I heard that the lithium battery uses the pulse method to charge, and the USB interface provides a constant voltage and constant current. It is not suitable for directly charging lithium batteries. Disassemble the charger and found that the charger is very simple, with only one transformer. It is used to convert 220v high voltage to low voltage; a rectifier block is connected to the secondary of the transformer to convert alternating current to direct current, and it is connected to a 2.5mm plug. The circuit needed to charge a lithium battery may be integrated on the mobile phone. From this point of view, as long as you change to a different mobile phone power plug, you can use usB to charge your mobile phone. According to these analyses. I made a straight-through USB charger, which is more convenient. No need to carry more things.

　　First prepare a USB extension cord, and cut off the female end of the USB extension cord according to the required length of the charger. There are a total of 4 wires in the USB extension cable, two of which are power wires, corresponding to the red wire and the black wire, and provide a voltage of +5V, of which the red wire is the positive electrode; the other two are the data wires. The corresponding wire colors are white and green. If the USB extension cable has a shielding layer, the shielding layer should be grounded. Because it is a charger. Only the power cord is needed, so cut off the two data cords and keep the power cord for backup.

　　The cut USB extension cable should be well insulated, and the unused wires should be cut from the root to avoid short circuit. If you can buy a ready-made power plug, it will be much more convenient, just connect it directly. If not, you can remove it from some used chargers (to reduce the cost!), cut off the power plug on the charger, and peel off the outer insulating rubber. There are usually red and white or red and black wires inside. Respectively correspond to the positive and negative poles. In fact, the wiring sequence can also be seen from the power plug. The inner core of the power plug is connected to the positive pole and the outer core is connected to the negative pole. You can measure it with a multimeter.

　　Solder the cut USB extension cord and power plug together with an electric soldering iron. Don't forget to check it again when soldering; you can't reverse the connection sequence of the money guide. Otherwise, it will be troublesome and even cause damage to the phone. After welding, confirm that it is correct, and then use insulating tape to wind up the connection to avoid short circuit. If possible, it is better to use heat shrinkable tubing, which has a high safety factor and is easy to use. Plug one end of the modified USB charger into the USB port of the computer, and plug the other end into the power jack of the mobile phone. Power on, the USB interface is powered, and the phone displays the words "Charging", indicating that the transformation is successful. In the future, as long as you bring this USB charger, you can use the US8 port to charge your mobile phone anytime and anywhere, which is more convenient for friends who have a laptop.

　　Because it is handmade. therefore. The finished product may not be as beautiful as the chargers sold in the market, but looking at the results of my labor, I still have a sense of accomplishment, and I made such a USB charger. You can also choose different power plugs according to your needs, which is more flexible. The transformation process is very simple. The most important thing is to find the positive and negative poles of the USB cable and connect the wires with the same definition one by one. This is the key to the success of the transformation. In ten minutes, let the USB play more functions, why not do it?

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