How to Make a Power Over Ethernet (PoE) Adapter

Many of us may feel the need to wall-mount our wireless routers on a wall or even outdoors in the balcony or garden. However, the lack of a nearby plug point is often a stumbling block because such a situation is rarely thought of while electrically wiring a home. Getting an electrician to create an electrical point will cost you Rs 800 to Rs 1,000, or even more. So what do you do to get your router out there without spending that much?

PoE or Power over Ethernet seems like the only answer, but a PoE injector would also cost you a few hundred rupees and is not so easily available. We show a technique, using which, you can make a PoE cable by yourself with absolutely no cost involved. All you need is a sharp knife and some electrical tape, but be prepared to cut your router’s power adapter wire, as well as the Ethernet cable. Do this at your own risk.

Step 1

To begin with, cut off the router’s DC power adapter’s coaxial power plug with approximately three inches of wire attached to it. Peel off the protective sleeves of the wire and keep it ready (see image 1). Using the knife, carefully peel the outer protective sleeves of the Ethernet cable from both ends at around three inches from the connectors. Be careful not to cut the wire cores inside.

Step 2

Next, locate the wires that are not in use. Generally, CAT5 Ethernet cables have four pairs (eight cores) of wires inside them of which only two pairs are used, while the other two are spare. These spare wires are connected to pins 4, 5, 7 and 8 of the RJ45 connector. You will need to cut-off the spare cables from the connector end and expose the inner cores of these four wires at both ends of the Ethernet cable (see image 2). Now twist the ends of each pair at one end of the Ethernet cable and join each pair to the coaxial connector’s wires accordingly (see image 3). Do the same with the other end of the cable with the power adapter’s wires.

Step 3

Note the polarity of the wires and match them with the Ethernet cable’s colour-coded wires. Usually, the power adapter’s wires have some type of colour code printed along its length for easy recognition. Once done, use some electrical tape and neatly seal the exposed wires, making sure they don’t touch each other. Finally, connect the Ethernet cable to the WAN port and the power connector to the power socket of the router respectively (see image 4). Power on the router and test it. Your router is now ready to be wall-mounted anywhere depending on the length of the Ethernet cable you use.

This method works with approximately five meters of Ethernet wire. If you need to use longer Ethernet cables, you would need to use a higher voltage power adapter (around 9 V to 12 V) and connect a voltage regulator at the router’s end to drop the voltage back to the desired amount. This is because with the length of the cable, the resistance increases and drops the voltage below the router’s operating power requirement.

Most routers generally need 5 V DC. Therefore, you can use a 12 V DC (switching power supply) adapter and step down the voltage to 5 V using an LM7805 voltage regulator IC, which is available for less than Rs 50. Please check your router’s voltage specifications before attempting this workshop for longer wire lengths.