Black Hole
May contain traces of nut
Ref external PSUs: even a wall-wart can be plugged into an extension lead.
External PSUs are an economy measure, in more ways than a non-engineer might realise. With an internal PSU, either the mains lead has to be detachable (additional expense, and more problems re certification), or different variants are required for different markets (differing styles of mains plug, which are required to be permanently fitted to the mains lead). The heat dissipation in deriving the internal DC supplies from the mains is internal to the enclosure, so suitable cooling needs to be designed in (with associated manufacturing cost and limiting the marketing boys' flair for weird design). Finally, the product will require high-voltage safety certification, in addition to the low-voltage directive, EMC, etc.
With an external PSU brick or wall-wart, the high-voltage part of the certification is hived off to the PSU supplier, and the heat generated is external to the unit. It becomes "somebody else's problem" - always handy in the world of design.
That's not to say I like an external PSU any more than anyone else, and if there is market pressure to ditch them...
External PSUs are an economy measure, in more ways than a non-engineer might realise. With an internal PSU, either the mains lead has to be detachable (additional expense, and more problems re certification), or different variants are required for different markets (differing styles of mains plug, which are required to be permanently fitted to the mains lead). The heat dissipation in deriving the internal DC supplies from the mains is internal to the enclosure, so suitable cooling needs to be designed in (with associated manufacturing cost and limiting the marketing boys' flair for weird design). Finally, the product will require high-voltage safety certification, in addition to the low-voltage directive, EMC, etc.
With an external PSU brick or wall-wart, the high-voltage part of the certification is hived off to the PSU supplier, and the heat generated is external to the unit. It becomes "somebody else's problem" - always handy in the world of design.
That's not to say I like an external PSU any more than anyone else, and if there is market pressure to ditch them...