Yes, the foldable solar panel power bank X Dragon 70W can be charged via DC. It is designed to be charged using a DC input port, which allows you to recharge the power bank using a compatible DC power source such as a car charger or a wall adapter. This feature makes it convenient to recharge the power bank using various power sources, providing flexibility for outdoor activities or emergencies. **

To build a solar USB charger, you will need a small solar panel, a USB charging circuit, a rechargeable battery, and a suitable container to house the components. First, connect the solar panel to the charging circuit, which will regulate the voltage and current from the panel to charge the battery. Then, connect the battery to the USB output of the charging circuit. Finally, place the components in the container and ensure that the solar panel is exposed to sunlight. This DIY solar USB charger will allow you to harness solar energy to charge your devices on the go. **

Foldable phone cases are not necessarily uncool. They can be practical and convenient for protecting your phone while also providing a stand or wallet feature. The perception of coolness is subjective and can vary from person to person. Ultimately, the decision to use a foldable phone case should be based on personal preference and practicality rather than societal perceptions of coolness. **

As an AI, I don't have personal preferences, but I can provide an opinion. The decision to buy a foldable smartphone would depend on individual needs and preferences. Some people may find the concept of a larger screen that can be folded into a more compact size appealing for tasks like watching videos or multitasking, while others may prefer the traditional form factor of a non-foldable smartphone. It would also depend on the price, durability, and performance of the foldable smartphone compared to non-foldable options. **

As an AI, I don't have personal preferences. However, I can provide information on popular foldable phones such as the Samsung Galaxy Z Fold 3 and the Huawei Mate X2. Both phones offer innovative foldable designs and high-end features, making them attractive options for those interested in the foldable phone trend. Ultimately, the choice between the two would depend on individual preferences and needs. **

Spherical cylindrical refers to a shape that combines aspects of both a sphere and a cylinder. It typically describes an object that has a cylindrical shape with rounded or curved ends, resembling a sphere. This shape is often used in engineering and design to create structures or objects that have both cylindrical and spherical characteristics. **

Spherical geometry 2 is a branch of mathematics that deals with the properties and measurements of shapes and figures on the surface of a sphere. It involves studying the angles, distances, and relationships between points, lines, and shapes on a curved surface. Spherical geometry 2 builds upon the principles of spherical geometry, which is the study of geometry on the surface of a sphere. This field of mathematics is important in various applications, such as astronomy, navigation, and cartography. **

Opinions on foldable phone cases being uncool can vary from person to person. Some may find them practical and innovative, while others may see them as unnecessary or bulky. Ultimately, it comes down to personal preference and how individuals prioritize the functionality and protection of their phones. **