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.                       
                                         
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