DIY PSU load tester

[Agent24]

Re: DIY PSU load tester

It looks awesome... like something out of Half-Life 2...

[goodpsusearch]

Re: DIY PSU load tester

Oh my god! It's huge!!!

You really did a very good job. Please test as many power supplies as possible.

Congratulations from Greece!

[c_hegge]

Re: DIY PSU load tester

...Please test as many power supplies as possible...

Will do. I've already tested 3 (1 of which survived) and one of these is next in line.

[Th3_uN1Qu3]

Re: DIY PSU load tester

Mmm switches. My meters have arrived, but only six of them, waiting on another four. I also have to decide upon the size of switch that i'll be using for the short circuit test. Only when all of them are here will i be able to start cutting the front panel.

In the meantime i'll be designing the ripple meter circuit. Coz IMO the point of my load tester isn't as much testing the power output (although it will be VERY able to do so), but rather testing voltage quality. Just like Hardware Secrets does.

[Agent24]

Re: DIY PSU load tester

I thought ripple was best measured with an oscilloscope for a good visual representation?

[PCBONEZ]

Re: DIY PSU load tester

It is.

[momaka]

Re: DIY PSU load tester

Here. It looks horrible, I know, but it works.

Exactly. As long as it works, that all that matters.

like something out of Half-Life 2...

Welcome to the Black Mesa Research Facility. The time is 8:47 am. Today, you will test power supplies with this new PSU tester of doom. Please put on your hazardous suit.

[Th3_uN1Qu3]

Re: DIY PSU load tester

I thought ripple was best measured with an oscilloscope for a good visual representation?

Yes. I will be using my 'scope as reference to calibrate the meters, but i want something self-contained and that displays all rails simultaneously. As long as the peak value is read correctly, it doesn't matter what you use to read it.

[PCBONEZ]

Re: DIY PSU load tester

Not certain but I think the meter response time will be too slow all you will see is the average DC.

[Th3_uN1Qu3]

Re: DIY PSU load tester

Not if i separate the ripple (AC component) from the DC, amplify it, rectify and filter, THEN apply it to the meter.

[Ken256]

Re: DIY PSU load tester

Interesting reading, I enjoy seeing other people's projects. I just started prototyping an active load tester. Right now I am using 2N3055 bipolar transistors mounted to old cpu heat sinks. The cpu heat sinks give really good performance when provided with ventilation. I measured a temperature rise of 15 degrees with 90 watts dissipation, so about 0.17 C/W. They just get warm to the touch. I should still have some margin at 90 watts.

I think with my next setup I will try some AOT430 mosfets. They are supposedly rated for 268 watts in a TO-220 package. I'm a bit skeptical that a TO-220 package can dissipate near that much power. But they're cheap, only $1.30.

Here's a question for people using mosfets in their load tester. Can the mosfets be connected in parallel, drain to source directly? Mosfets should share the load equally because channel resistance has a positive temp coefficient? Right now I am using 0.33 ohm emitter resistors in my active load tester to ensure load sharing.

[Th3_uN1Qu3]

Re: DIY PSU load tester

Here's a question for people using mosfets in their load tester. Can the mosfets be connected in parallel, drain to source directly? Mosfets should share the load equally because channel resistance has a positive temp coefficient? Right now I am using 0.33 ohm emitter resistors in my active load tester to ensure load sharing.

Yes. The only time i blew some of mine was when i didn't screw them to the heatsink tight enough, and they wiggled loose. With bipolars you need emitter resistors, with MOSFETs you don't.

I'm waiting on the last batch of meters and will decide on the type of switches today. I already have bought a 50 watt 12-0-12 transformer, should be enough for powering the 8 fans and all associated control circuitry. You'll be soon seeing a nice front panel. I'm also going to be prototyping the first ripple meter in the next few days.

[c_hegge]

Re: DIY PSU load tester

I made a few modifications to mine. I added a slightly molded and bent PSU case to the end to use as a duct for hot testing and I found some of those 250CFM Delta fans on Fleabay for only $80 for 3 of them. I'm going to replace the two 120mm fans with them as the bottom gets a bit hot when I set it for drawing 350W or more. It should run cooler that way. I just hope the neighbours don't complain about the noise.

[Th3_uN1Qu3]

Re: DIY PSU load tester

I just hope the neighbours don't complain about the noise.

Good one.

The ripple meter design is good to go on mine - it's just that i've caught a nasty cold and what doesn't run thru my nose, runs thru my eyes. As you would imagine, constantly teary eyes are rather impairing.

[c_hegge]

Re: DIY PSU load tester

Sorry to hear. Hope you get better soon.

[c_hegge]

Re: DIY PSU load tester

Oh dear! I think I'm going to go deaf soon. I replaced the two 120mm fans with the deltas and the airflow is lovely but it sounds like a jet engine

[Th3_uN1Qu3]

Re: DIY PSU load tester

Time for a fan speed controller methinks.

[Toasty]

Re: DIY PSU load tester

<<----performs New York CPR....

*kick*

*KICK*

Get UP!! You're blocking the sidewalk!

[Th3_uN1Qu3]

Re: DIY PSU load tester

If this is supposed to be a reminder, well, i have all parts AND found a case for it too. Now it's just gonna need a little more time. I have lots of stuff to do not mentioning that second semester at uni is starting next week...

I'm going to start making the main controller board since everything else patches into it.

[Toasty]

Re: DIY PSU load tester

Okay. Good.

It covered a lot of ground in 2-1/2 months then dropped dead.

Thought maybe you got stunned or something...

.