I bought a very nice $250 ThermalTake ToughPower 850w Modular PSU for $100 last week and I want to write a review for it. However, to write a review I need to measure the voltage the 3.3v, 5v and each 12v rail outputs. I also need to measure the effiency of the PSU which would be watts output/input. To do that I need to find out the Amperage of the 3.3v, 5v and 12v rails.
I saw like $400 multimeters and $150 amperage meters but I can’t afford that. I have seen some review sites make their own boxes that can load the PSU with like 500w or so and then a lot of funky displays output the different voltages and stuff.
I was wondering if anyone here knew of any tutorial sites or schematics of how to make one of these buggers. I don’t have a lot of money left, so as cheap as possible would be nice. I don’t want it to go poof though because I love my new power supply.
If you guys don’t understand what I am talking about, I can get you some pictures of it.
You shouldn’t have to spend much $$$ to test the output of the power supply. You could six of the below multimeters for ~$25. Use two on each output rail, one to measure the output voltage, and the other to measure the current up to 10A. Get a couple of cheap light bulb four packs and use the bulbs in various combinations of series and parallel for dummy resistance loads. Vary the loading and record the current vs rail output voltage.
I have a very nice $80 radioshack multimeter (with RS232 =D).
The A ratings on the rails goes between 18 to 30A though. To test 30A you need a very expensive one!! Not to mention I would need 10 x 60w light bulbs. I don’t want to be blinded or burned.
I seen a few power supply test units for like $175, but I can’t afford to pay that much.
I seen someone put together one of these measuring tools with like some weird little cubes (loads i am guessing) a large transformer like thing and some gauges).
If your RS multimeter is a good one, you only need it and the bulbs for loads to do your testing. Measure the resistance of the bulbs (my $2.99 meter says my 60w bulb has a resistance of ~17.2 ohms). Connect it across the 12v rail and measure the rail voltage. Use E=IR to calculate the current value. You might see something like 11.7v/17.2 ohms=.68a. using four bulbs in series with a resistance of 4.2 ohms, you might see something like 11.5v/4.2ohms=2.7a. Adding load you might see something like 11.1v/.9 ohms=12.3a. Doing this depends on how well your meter can measure low resistances and how well you develop the loads.
In this setup you don’t mesure the current, you calculate it by measuring the resistance and the voltage, so you shouldn’t blow a fuse. Use google to find a lot of info and diagrams.
Your very good!!! I keep forgetting about the basic equations 
8)