"budgie" wrote in message
...
On Sat, 6 May 2006 14:03:45 +1000, "Peter"
wrote:

http://members.ozemail.com.au/~pebar...N3055schem.jpg
A fellow hobbyist told me it was not a good circuit arrangement as it had
poor regulation with the NPN pass transistors. Can someone explain to me
why?

He's right, it's not a good circuit. The current-sharing emitter
resistors will
degrade the regulation. The regulated point is their base junctions.

3-terminal regs have an internal feedback ararngement that regulates their
output pin voltage, meaning anything after that is effectively
unregulated.

As a further point, look up the hFE of a 2N3055. It seriously sucks as
the
collector current rises. Three x 2N3055 at 20 A is gonna take a LOT more
drive
than a (non-moose) 7805 will provide.

max hFE of 2N3055=20

non-moose?