Check out this Enermax 1000 Watt PSU review

All of you guys should read the excellent review of the Enermax 1KW PSU at this link: http://www.pcper.com/article.php?aid=310&type=expert&pid=1 . This guy that did the review really has his act together and knows how to take measurements with proper equipment. I only wish I had the money to configure a similar test setup. :veryprou:

Unholy - please note that he also built a PSU load tester.

 

Well that article was interesting from a "audio amp designers" point of view... I've never seen that formula PF = True Watts / Volt Amp, the problem is too get the "true watt" measurement. I've been designing audio and radio(AF/RF) amp's since I was ten... and during my ten years as an amateur(from that I was ten to I was done with my Master degree in Electronic Engineering) and my twenty as an Engineer I've never been able too build, or buy a test equipment that is 100% accurate in measuring Watt! Watt or P is the factor of volt times ampere. What the author of this article claims to be "True power", is what he has measured as some kind of efficiency. And called that "pf", or power factor. Well it's one way of doing it, and it might be relative accurate. When we(I) measure r.m.s power hadling, say in a B-class amplifier, you use a dummy-load, and when the amplifiers amp stops climbing, maximum has been reached, and the voltage start to fall, then you know its limit!
So what am I saying? Well you don't need an expensive test instrument, all you need is a good DMM, and something that you can adjust as load. I use ten BJT's, MJ15003, in parallel, and a couple of OP-Amp's and a multi-turn pot, to regulate the base current of the MJ15003's. You can find good circuit diagrams on the net or on my home page 'webench.net'(it's not up yet though.. but I take every chance to "spread the word"). And by change the base current of the "load" the transistor will "pull" more and more current. I've designed it so I can change the function, a constant-current-load or a power-resistor... So you don't need to spend a gezillion euro or dollar on a test equipment that isn't accurate to begin with. The best way to measure "True Watt" is w/ an inductance(a coil), and then you pull the cable through the coil and get a vale of it's magnetic field - this only works with AC... the stronger the field = more W.. but you need a bunch of formulas to get that one right... oops, this became way longer apply than I intended.... sorry, but I got hung up on the "true power". When we build amps with linear PSU, we use as a rule of thumb, that the specified VA*.8, so 100VA is about 80Watt...