GL-INET AR750 conversion to 5VDC

I own one of these Travel Routers. It's great for connecting multiple things to the single Internet feed in a hotel room or camp site. The problem is that it uses a USB power supply and if one does not use the correct cable the router becomes unstable. This is due to the voltage losses in the thin wire used in cheap USB cables. The router is quite thirsty and so requires a cable that can deliver a good half an amp.

GL.INET AR740 Travel Router

I want to use this router for camping. I want to have this router be the Access Point that my phone and laptop and TV connect to. In turn this router will connect (usually by WiFi in WISP mode) to whatever Internet I can find. To this end I need to power it from my 12V camping batteries or solar panels.

One of the optional extras for this router is a Power Over Ethernet (POE) board which will take the 48V from your POE capable network switch and convert it to the 5V needed to power the router. 

POE Adapter

I opened up the router and found the pins that would receive the 5V from the above POE board. This discovery was greatly helped by the below picture that I found on the manufacturers website.

Now that I have established how to connect 5V to the board I need to come up with a 12V to 5V DC-DC power supply. Luckily Amazon is full of them. For a previous project I bought some LM2596S variable DC-DC power supplies. These are available from all the usual online places such as Amazon and Ebay for around $1 each.

LM2596S DC-DC "buck boost" converter.

A word of warning; before connecting this power supply to your Router (or Raspberry Pi etc) make sure to set the output voltage to whatever you need it to be.  This can be achieved by connecting your power source to the input then turning the screw on the variable resistor (the blue block thing) whilst measuring the output with a volt meter. I set mine to 5.02V.

Next was a session with my 3D printer to create an enclosure. Thingiverse.com was my friend here. However I had to print a second power supply case as the lid to the first one would not fit. The capacitors on the board were too tall to allow the lid to fit.

DC-DC converter in 3D printed case

Time to test it all. I wired the power supply into the router and gave it an initial "smoke test". No smoke was observed this time. Everything seemed to work as expected.

DC-DC power supply connected to the router

DC-DC power supply and router wired together

All wrapped up with in their respective cases

The final step was to install in onto the electrical board that I use when camping. The board holds the solar charger, fuse board, 110V inverter and battery charger. This seemed like a logical place to install the router as power is available right there. I also installed the POE injector for a TP-Link WiFi bridge with high gain antenna that can be remotely placed (for example, on my portable radio mast) to bring in the WiFi signal from further afield should it be needed. 

Router installed on power board

A quick trip to my local WholeFoods Market (where they have free WiFi) was made to test the whole system. It worked flawlessly. Here are some screen shots from the test tools I used.