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Testing Methodology Discussion Questions and comments regarding the testing methodologies used on jonnyguru.com

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  #11  
Old 10-14-2016
ridgid13579 ridgid13579 is offline
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Quote:
Originally Posted by ITelektro View Post
I've try some from ebay and just given up. They are so inaccurate that it simply there is no point to use those. It crossed my mind to buy a cheap uni-t multimeter and put it in case. If you find something acceptable, paste link.
My grandfather has some real nice german made panel meters... But they're analog. (More like a whole unused box of them)

Those $1 ebay ones are trash. Don't even both with them.
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  #12  
Old 10-15-2016
Behemot Behemot is offline
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There are some as cheap as 1 buck?

Anyway seems that there may be some problems running multiple meters from the same power supply according to a post on EEV depending on how the meters are internally wired. Trying to search for more information ATM.
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  #13  
Old 10-15-2016
ITelektro ITelektro is offline
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Originally Posted by ridgid13579 View Post
My grandfather has some real nice german made panel meters... But they're analog. (More like a whole unused box of them)
Those $1 ebay ones are trash. Don't even both with them.
Oh this old thing ..... I will never get over because I sold the old analog oscilloscope Hameg .....
I tried the cheap ones from a couple of dollars and those of 30usd ..... just do not have confidence in these instruments because proved to be inaccurate. Now I use Uni-T 200 series dc clamps and ac / dc clamp to the oscilloscope for current control.
When catch time I check why this is so imprecise, if the problem is in shunt or / and in the meter.

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Originally Posted by Behemot View Post

Anyway seems that there may be some problems running multiple meters from the same power supply according to a post on EEV depending on how the meters are internally wired. Trying to search for more information ATM.
In my case it was not a problem. I made a linear power supply with the necessary rails and built it into a dc load. So it should not be a problem
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  #14  
Old 10-15-2016
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Nuckles_56 Nuckles_56 is offline
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Originally Posted by quest for silence View Post
Thanks for the reminder I spend too much time having to consider that whilst I write my thesis
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  #15  
Old 10-15-2016
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quest for silence quest for silence is offline
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Thanks for the reminder
You're welcome: it was a reminder for me too, and best wishes for your thesis!
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Best, Luca
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  #16  
Old 10-15-2016
ITelektro ITelektro is offline
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There are also reviewers who have managed to build their own loaders. However, their test results are questionable since they cannot be reproduced.
I just read this on Tom's Hardware site.
According to this, it appears that with diy elecronic load is not possible to make accurate results. Perhaps author of this text is participating on this forum?
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  #17  
Old 10-15-2016
rafal_iB_PL rafal_iB_PL is offline
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According to this, it appears that with diy elecronic load is not possible to make accurate results.
Rather REPEATABLE results. They seem to cling to the same assumptions that are made for CPU/GPU testing - and those don't seem quite valid in PSU realm.
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  #18  
Old 10-15-2016
ITelektro ITelektro is offline
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That is so wrong, but I would certainly like to hear arguments for such a thing to write.
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Originally Posted by rafal_iB_PL View Post
Rather REPEATABLE results.
And even in this case it is still wrong.
Diy dc load is not a measuring instrument, it's just a load. Which measuring instrument will be controlled conditions will determine the precision and accuracy.
So if I control setpoint current with my multimeter accuracy of 0.0035 + 0.0005 and a high precision shunt of 0.01% will have a more precise and more accurate results than on the Croma (0.1%), and the results will be repeatable, and accurate within these 0.01%.
In other words, the constant load of 1A is 1A load whether it comes from Croma load or something else it does not matter.It is important is that 1A and that it can with some certainly confirm. In this case within 0,01%

Last edited by ITelektro; 10-16-2016 at 05:24 AM.
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  #19  
Old 10-16-2016
rafal_iB_PL rafal_iB_PL is offline
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They seem to mean "repeatable on different configurations". Within the same configuration results are repeatable, and I know that from experience. If they meant that, that was complete nonsense.
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  #20  
Old 10-16-2016
Behemot Behemot is offline
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Maybe the explanation is simple…there is growing competition of ppl with home-made HW producing high-quality articles. They are starting to loose readers so they came up with this, which, translated, reads as "we, and couple others who have big money to buy branded stuff, are the only good ones so don't read the others". Just added some wannabe technical bubbling so average Joe does not see it through right away.
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