22 Aug
2006
22 Aug
'06
3:23 p.m.
I'm still surprised that there were any beebs
incapable of running the Torch
board from their own PSU though. I believe there was a change to PSU spec at
some point early in the beeb's life though, so maybe very early systems
couldn't cope.
Very early Beebs have a linear supply (a torroidal transformer and a
number of 7805 regualtors IIRC). On early Beeb boards, the 3 5V pins are
separate, and each is supplied by a different 7805. Later boards,
designed for use with the SMPSU, have the 5V pins connected together.
This linear PSU was well-known for burning the varnish off the dining room
table....
-tony