The power terminals on a USB cable are the red and black wires; the red wire is your positive voltage (VCC), and the black wire is your ground (GND).
Understanding USB Power Wiring
USB cables have four wires (typically):
- Red: Positive voltage (VCC), typically +5V
- Black: Ground (GND)
- White: Data Negative (D-)
- Green: Data Positive (D+)
For simply supplying power, you only need to concern yourself with the red and black wires.
Wiring for Power
To wire a USB cable solely for power, follow these steps:
- Identify the Wires: Carefully strip the outer insulation of the USB cable to expose the four internal wires (red, black, white, and green).
- Isolate the Power Wires: Separate the red and black wires from the white and green data wires.
- Connect to Power Source/Load:
- Connect the red wire (VCC) to the positive (+) terminal of your power source or to the positive terminal of the device you want to power.
- Connect the black wire (GND) to the negative (-) terminal of your power source or to the negative terminal (ground) of the device you want to power.
- Insulate: Properly insulate all connections to prevent short circuits. Electrical tape or heat shrink tubing are suitable options.
Important Considerations:
- Voltage: USB typically supplies 5V. Ensure the device you are powering is compatible with this voltage. Using a voltage too high can damage the device.
- Current: USB 2.0 ports typically provide up to 500mA (0.5A) of current, while USB 3.0 ports can provide up to 900mA (0.9A). Make sure your device doesn't require more current than the USB port can provide.
- Data Wires: The white and green data wires are not needed for power-only applications and can be safely ignored or cut short and insulated. Be careful not to short these to each other or to the power wires.
- Safety: Always exercise caution when working with electrical wiring. If you are unsure about any step, consult a qualified electrician.
Example Use Cases
- Charging a small electronic device: You can use a USB cable to provide power to a small circuit or device that requires 5V.
- Custom USB power adapter: Create a custom adapter to power a specific device using a USB port.
By following these steps, you can successfully wire a USB cable for power-only applications. Remember to prioritize safety and ensure compatibility with your devices.
