Power over Ethernet (PoE) is a technology that allows ethernet (network) cable to carry electricity in order to power a device. PoE brings cost saving advantage in the sense that you only need to use a single cable for both data and power. It also gives flexibility for a device to be located far away from an electrical outlet and can be repositioned easily if needed. PoE is widely used in wireless networking equipment, IP cameras and VoIP telephones.
This set of cable is using the basic idea of PoE, carrying electricity using the unused wires in ethernet cable. However, be aware that these are passive cables and they do not follow the standard PoE implementation which require devices to support PoE. This cable set can be used even if the device does not support PoE. The set comes in two pieces, an injector and a splitter.
The injector has an ethernet RJ45 male plug, a 5.5x2.1mm DC power jack, and an RJ45 female socket. The male RJ45 connects to a data source like a network router or switch. The power jack connects to the power supply, for example a 12V DC wall adapter. The injector merge in the power to the ethernet with pin 4 and 5 connect to the positive 12V DC in this example and pin 7 and 8 connect to the ground. An ethernet cable (not included) connects to the RJ45 socket and the other end of the cable connect to RJ45 socket of the splitter. The splitter splits back the power from the ethernet to the 5.5x2.1mm DC plug. You can connect this DC plug to the power input socket of a device. The splitter also has an RJ45 male plug which connect to a network port of the device.
Take note that depending on the length and material used for the ethernet cable, expect some voltage drop especially when the ethernet cable is more than 10 meter long.
Protip: It is also possible to use this cable set to connect a router to an SBC like a Beaglebone Black or Raspberry Pi. Use a 12V power source at injector's end and use a buck converter at splitter's end to bring the voltage down to 5V DC that is suitable for the SBC.
Technical details:
Connector:
Injector: RJ45 male and 5.5 mm x 2.1 mm female (12DC power in), standard female RJ45
Splitter: RJ45 male and 5.5 mm x 2.1 mm male(12V DC power out), standard female RJ45
