retrolefty:
I think the main disadvantage of this circuit is the inefficiency due to the 1 ohm feedback resistor which leads to lots of wasted power. I would redesign it using a .1 ohm resistor and scale the feedback op-amp to compensate.
Thanks for the feedback. You are probably right in terms of efficiency, weighed against the difficulty of finding a 0.1 ohm resistor with high accuracy. I think Dave did his 1 ohm resistor by putting 10 x 10 ohm in parallel, which tends to indicate that he found the likelihood of finding a 0.1 ohm resistor rather low.
I've got one here, I wonder if the heat would make 0.1 ohm drift faster than 1 ohm? I suppose there are always trade-offs in this sort of thing. For situations where you might just want to test a "wall-wart" to see if it delivers the promised voltage at the promised rating, a few seconds' test would probably suffice, in which case you don't really care if you waste power or not.