The main power supply is built into bottom half of the box and is made up of commercial off the shelf switching units, connected together with a set of switches and supplying power to the electronics in the lid of the box via a 40pin ribbon cable and connectors. The power is provided by either a mains inlet and 12V dc switching psu, or via an XLR socket intended to receive power from a 12V battery supply, if in use in an RV but could be a battery carried in the box itself. Power from either of these is selected via a three way switch, mains, battery or centre off position.
The power is switched by an illuminated rocker switch to indicate power on. The main power on provides power to the other switches and to a 12V buck-boost supply providing power to the lid electronics. This also feeds to a simple negative voltage generator for the analogue components in the display.
A 5V buck-boost module is supplied by an illuminated rocker switch and provides 5V for use by constructed circuits in the lid and is routed via the ribbon cable.
A +/- 12V buck-boost module is supplied by an illuminated rocker switch and provide both a +12V and -12V supplies for use by analogue circuits and is routed via the ribbon cable.
A fourth buck-boost module is fed from the final switch to provide power to the USB hub. The USB 2.0 hub is a low cost item which provides four power switched sockets as well as the logic to run as a hub. More on this later.