[_] (OT) Basic electronics
Oliver Humpage
oliver at watershed.co.uk
Sat Aug 12 13:36:14 BST 2006
On 12/8/06 12:18 pm, "adam armfield" <adamairmailed at yahoo.com> wrote:
> i've been pondering writing to the council &
> suggesting they rip out all the power supplies in
> their pc's and have some big 12v loop in the
> building... maybe not exactly that but power over
> ethernet looks good
The spec for PoE is 48V, for the P = R*I^2 reason (that is, power lost is
proportional to current squared - and the higher the voltage, the less
current you need to get the same power).
Presumably, however, one could save energy by building a box with one large
12V transformer in it and lots of sockets. You could then just make up a
load of custom cables, with your equipment's plug at one end, and whatever
socket is on the box at the other, and plug all your equipment in.
You could also just switch off this one box overnight, rather than unplug
loads of little transformers.
Or would this not save any energy at all? I suppose it depends on the
quality of the transformer you use...
Oliver.
> i've been pondering writing to the council &
> suggesting they rip out all the power supplies in
> their pc's and have some big 12v loop in the
> building... maybe not exactly that but power over
> ethernet looks good
The spec for PoE is 48V, for the P = R*I^2 reason (that is, power lost is
proportional to current squared - and the higher the voltage, the less
current you need to get the same power).
Presumably, however, one could save energy by building a box with one large
12V transformer in it and lots of sockets. You could then just make up a
load of custom cables, with your equipment's plug at one end, and whatever
socket is on the box at the other, and plug all your equipment in.
You could also just switch off this one box overnight, rather than unplug
loads of little transformers.
Or would this not save any energy at all? I suppose it depends on the
quality of the transformer you use...
Oliver.