AG - where's "over there"? Not over here I hope!
John - that makes very interesting reading, and an angle I'd never thought of. I see they have chosen the value that lies at the kink in the efficiency graph. I wonder if a similar exercise with pn junctions would yield a similar result. There's an experiment to do here...
ElinarA - suck it and see, then!
KISS - Ahhh, I see the answer!
I once had a power supply from a mainframe computer when a lot of them were being scrapped (1983/84). It had for the 5V pass element maybe 6 or 8 2N3055's on a big heatsink. Each had a resistor in series with its emitter, They were aluminium cased, bolted to the h/s, 1 ohm I think (or it might have been 0.1 ohm). Never really thought about how they worked out that value, at the time, often thought about it since, but especially since I've been interested in boost converters with high input currents, and using paralleled devices becomes attractive.