The power supply V1

The basic wiring is to provide a nominal switched 12V at a pair of banana sockets in the base section of the box.

There are two inlets on the box. A standard IEC socket, fused and with an illuminated switch provides a local mains connection. I've used my own separate mains PSU for many years and not having an illuminated switch has been a frequent irritation, so I appreciate adding one now. The other inlet is an XLR 3pin male socket, rated for 16A, and which will be used with cable to connect it to a 12V battery system. This will be either in my cabin, adapted for solar power, or in my RV when away.

The mains inlet feeds a 12V switched mode power supply setup for the local mains voltage and providing up to 8.5A, and particularly sized to fit into the box. Larger PSUs were available for not much more money but they both wouldn't fit and also are not necessary in just a small workbench environment.

Both the battery and PSU are connected to a common negative rail and individually to two poles of a changeover switch with a centre off position so that power can be selected from either source or isolated completely. Rocker switches were chosen for this roll so as to not interfere with the project wiring when the box lid was closed.

The positive supply from the changeover switch is routed to the output via an illuminated isolation switch, again to provide indication that power is on. Using lit switches makes it easy for me to see what is happening.

Finally, the output from the PSU component is output via two 4mm banana sockets, nominally delivering 12V. The purpose of these is to either provide 12v directly to the projects assembled in the lid or to the additional stepdown PSUs and electronics in the lid, described in the next part.

Supplies

Various offcuts of 9mm plywood from the previous project, mostly 20cm wide.

1 x XLR male chassis socket, rated for 10-16A dc

1 x IEC mains socket with illuminated switch and fuse

1 x 12V switch mode power supply

1 x DPDT centre off switch

1 x SPST switch with LED

1 x Red banana socket rated to at least 10A

1 x Black banana socket rated to at least 10A

Short colour coded leads with spade connectors, see text