I’m not sure if this is in the correct forum. I want to mount Fire Tablet HD 10 on the wall next to my front door. The house is prewired with 4-wire 18AWG for a Control4 system, so I have some wires going from electrical closet to the install point. My question is how do I go from 120V to USB-C through these wires.
I believe I need some sort of transformer to take it from 120V to 24 or 12V and then get some other sort of down voltage regulator to take it to 5V or something along those lines. Has anyone figured this out and could you provide me with the products you used to make this work?
Your Fire Tablet is designed to take 5V DC power. The 4-wire 18AWG is ~120V AC power. You not only need to step down the voltage, but also covert to DC. Probably the easiest way to do this is simply to connect a ground, neutral, and hot to a standard outlet and plug in the adapter that came with your Fire tablet. You can even do this in a recessed outlet box that would fit behind the tablet holder on the wall.
How far away is the location you want to install the tablet from the location you want to supply the power from? The challenge of using such a low voltage is that the voltage drop of a long run is far more significant when you’re starting out with 5V than if you’re starting out with 120V or even 12V. If it’s a run of more than about 10 feet I would consider using a 12V power supply and putting a buck regulator behind the tablet to drop it down to 5V. Good quality 12V (or other voltage) power bricks or “wall warts” can be salvaged from scrapped equipment.
Yeah I don’t think I’d try running 5V over 40 feet, unless you use absurdly heavy wire you will probably lose enough voltage to cause erratic behavior. There are lots of ways of doing what you want, and it will depend on your expertise in various areas, budget, priorities which approach makes the most sense. A really simple way is to take a car charger and supply it with 12V from whatever suitable power supply you get your hands on, or you could use a module like this https://www.ebay.com/itm/DC-DC-USB-Buck-Regulator-Converter-9-12-24V-to-5V-Step-down-Power-Supply-Module/203045166286 which is essentially the same thing. I cannot speak for the reliability and performance of that specific product but there are many similar options.