C_hegge- RE: "DIY PSU load tester"

[TheLaw]

Hi,

I was reading this article you wrote a year or two ago. http://psurepair.freeforums.org/diy-...ester-t35.html Very interesting. I am trying to help another person from Overclock.net put together a PSU load tester...

What amperage switches did you use in series with each resistor? Would 2-3A be enough? And are those SPST?

Thanks.

[Evil Lurker]

Re: C_hegge- RE: "DIY PSU load tester"

SPST = Single pole single throw

Resistance is based upon ohms law and the applied voltage.

For instance, a 1 ohm resistor connected to a 5v output will generate about 25w worth of load... enough for a simple radio shack 10watt sandbar resistor to handle with proper heatsinking.

Since resistance is basically voltage squared divided by resistance, then connecting the same resistor to a 12v output will fry the resistor... 144w is just waaay too much for them to handle. Going to 5 ohms would get one in the 28-29w worth of load range.

Anyhoos, feel free to play with this calculator:

http://www.sengpielaudio.com/calculator-ohm.htm

Anyhoos a standard 1157 tail lamp is great for loading the 12v rail. The only thing is they are not linear in their resistance.. for a brief few microseconds until the filament reaches operating temperature they can pull 10-18x their rated current draw. Maybe enough to push a PSU over the edge especially if you try and load up a whole bank of them at once.

[c_hegge]

Re: C_hegge- RE: "DIY PSU load tester"

I just used switches from PSUs to build it, as well as a fw which I bought. I'll have to look at the ratings later, but the resistors on the 3.3v rail draw 10A each, so the switch will need to be able to handle at least that.