From: John Tserkezis 
Reply-To: Fidonet AVtech Echo 

David Drummond wrote:

> I too want a fixed output - fixed at 6.3V not 5 or 9 or whatever those things
> seem to come at.

  Many are available in both fixed and adjustable flavours.  The part numbers 
Brenton mentioned are adjustable parts.  You can pretty much pick any voltage 
you like.

> I've been considering Bob's idea of the series regulator - the LM350 looks like
> it would do, and the component count is lower than the switch-mode, with a
> simpler circuit.

  With a 3 amp load, and a 12v supply, you're looking at about 17 watts wasted 
dissipation, (about 53% efficiency).

> What do you think (assuming the 6V ida doesn't work......)?

  It works allright.  Depends on your needs and priorities.  Will probably be 
cheaper if you already have a chunk of aluminium to use as a heatsink.  Be sure 
to use heatsink compound or those 'rubberised' insulators.

  However, Brenton's idea of tapping off the 6v line (if you have access to the 
individual cells) would be a better idea, but remember you're sucking just 
those cells down, and not the whole lot, so, it may be an idea if you 
alternately use the top and bottom half of the cell stack.  Depends on how long 
you're going to be using it I suppose.

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