To: 999 (all members)
From: K8M (Mick York)
Subject: TECHNICAL TOPIC
HOW DO THEY DO THAT?
How does the BBC micro power supply
work?
So how does it work? Well one
end, called the import is used to suck
big volts out of the 3 holes in your
socket. Many of these sockets make up
a main ring, or socket set as it is
more commonly known. Each hole can
supply just four and one third volts
per hour. Three times this is 13, which
is why 13 Amp plugs are needed to suck
volts into the wire. Wire connects
between the socket and the power
supply and is in fact hollow to allow
the volts to pass easily. You cannot
see hollow with the naked eye; you
would need a large telescope. Nearly
thirty thousand such holes would fit
on top of a grand piano. When the big
volts get inside the power supply they
need to be squashed - this is where a
switch mode supply is different to
linear. In the linear supply,the volts
are simply pushed into a very small
hole until they squeeze through ;this
makes them get very hot and
bothered, but they come out in a
straight line. Which is why the supply
is called LINEAR.
In the switch mode type, each volt is
seperated out for individual treatment.
They queue up in front of a device
called a transformator and are selected
according to size by a miniature
version of a clarkes shoe size gauge
called a convincer. The volts are then
made to switch places in the queue
until just the right size to go through
the right hole in the transformator.
The convincer needs to know how many
volts are needed at the outport and for
this we use the principle known as
FEEDBAG. A small container that looks
like a feedbag is hung just under the
outport and catches any surplus volts
that can't squeeze down the outport
wire. Every now and then a three legged
animal which is a transvestite takes
the feedbag and empties it into a
hopper on an optical ice maker. This
makes ice in proportion to the surplus
volts, and freezes the queue at the
transformator, thus slowing down
throughput. This also helps the switch
mode supply to run a lot cooler than
others.
During the squashing process, the volts
are converted from assorted currants
(ac) into drift currants(dc) and of
course waste currants(wc). It is the
drift currants that go down the
outport, but before they are allowed to
leave the supply they must be smooth.
This involves something called a high
frequency sanding wave, which smoothes
off rough edges.
So there we have it (utter rubbish)
Many thanks to Cliff Rogers with help
on this article.
PRESS BREAK