I would simply connect these resistor in serie ... then connect a DC power supply to feed the voltage divider ( be carefull about power dissipation ! ) then measure voltage across each resistor .. voltagedrop across any of these resistor should be proportional to the resistance value. If you have a precision resistor with a known value put it in series with the others.
I recently had something I wanted to use a .1ohm resistor. Bought some and I always check. So I put it on my cheap handheld B&K and I think I got around .5 ohm. Did not surprise me and was close enough as shorting the probes got .4. After seeing this thread I figured I'd see what I got on my bench dmm I bought a few months ago. Much better, 2 wire mode got .14 ohm and 4 wire got .12. Then I tried just shorting the 2 wire mode probes and after a 30 minute warmup was 24mohm. Then took a piece of wire and did a 4 wire probe. 1 milliohm. I was kind of impressed for a 350 dollar meter. Even 2 wire mode was closer to zero than I expected. 4 wire really is noticeably better for low ohm R's.
858E from rigol. I just played again and yes, 4 wire is 1 or 2 mohm and stable immediately. 2 wire wanders for a while.
Nice, supports LXI also. Watch your AC frequency, at 8 KHz you may run into additional errors above 1 KHz. You can't use it for frequency response and we don't know what the rolloff is like.
Not a bad meter for $350 at all. Beats the heck out of teh cheap handheld meters many use, and you have four wire resistance. The trend function will be useful as well as relative dB.
Not a bad meter for $350 at all. Beats the heck out of teh cheap handheld meters many use, and you have four wire resistance. The trend function will be useful as well as relative dB.
You've just introduced more variables, and the person doing this probably will not have the experience to realise what those are.
Just do it correctly from the start.
I've always said (and trained techs) to never fight your equipment. If your equipment isn't up to the task, either buy something that is, or don't do the job you don't have the equipment to do.
Just do it correctly from the start.
I've always said (and trained techs) to never fight your equipment. If your equipment isn't up to the task, either buy something that is, or don't do the job you don't have the equipment to do.
Read this thread before investing in Rigol DM858
https://www.eevblog.com/forum/testgear/rigol-dmm-dm858-comparison-thread/25/
https://www.eevblog.com/forum/testgear/rigol-dmm-dm858-comparison-thread/25/
That Rigol unity is clearly faulty, but it seams to be that unity not the product itself, right?
@ron68
I am not sure which "unity" you are talking about, it's not only that one and only unit seen in the video, or OP's own unit on the EEVblog thread, the problem is reported by several people, from the comment section under that video one will find a couple more flawed DM858 reported.
It's a bitter repeat of the hope for "cheap" Chinese bang-for-the-buck instrumentation, like I wrote about LCR meters in this post 2 months ago (see the bottom portion), and the EEVblog links posted there.
ps. this is not the full post, it's some limitation with current forum SW as it only shows part of it, click on the post linke to see the whole post.
During last autumn I did look after a better function generator, but after looking up several models on EEVblog so many came out having some annoying bugs, I think my narrowed down search came to the conclusion Hantek HDG3000B Series 16 bit generator seemed Ok, but so far too few posts and I may have to redo my research on it, time will tell.
I am not sure which "unity" you are talking about, it's not only that one and only unit seen in the video, or OP's own unit on the EEVblog thread, the problem is reported by several people, from the comment section under that video one will find a couple more flawed DM858 reported.
It's a bitter repeat of the hope for "cheap" Chinese bang-for-the-buck instrumentation, like I wrote about LCR meters in this post 2 months ago (see the bottom portion), and the EEVblog links posted there.
@Sadface fingers crossed!
btw I just discovered by chance some more places where further store info is located on AliExpress, it's really a poor layout nowadays as the store info is spread out at 2 different places and each with their set of info.
One is on the item page, on the right side while hovering with the mouse over 'Sold by' on the upper-right side a drop-down window appears, pic below:
Click on 'Sold by' and it takes one to the stores homepage, there in the upper-left corner hover-over with mouse cursor on the store name and a drop-down window appears...
btw I just discovered by chance some more places where further store info is located on AliExpress, it's really a poor layout nowadays as the store info is spread out at 2 different places and each with their set of info.
One is on the item page, on the right side while hovering with the mouse over 'Sold by' on the upper-right side a drop-down window appears, pic below:
Click on 'Sold by' and it takes one to the stores homepage, there in the upper-left corner hover-over with mouse cursor on the store name and a drop-down window appears...
During last autumn I did look after a better function generator, but after looking up several models on EEVblog so many came out having some annoying bugs, I think my narrowed down search came to the conclusion Hantek HDG3000B Series 16 bit generator seemed Ok, but so far too few posts and I may have to redo my research on it, time will tell.
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Depending on one meter is a bad idea, no matter how expensive it is. If 2 or 3 meters agree then the reading is real, even if some of them are $5 Harbor Freight meters. I use them and I know that the leads are thin high resistance, and the switch has no gold, so it corrodes, but they are disposable and work just fine if you know what you are doing. I am not doing any QA with them and troubleshooting rarely requires much precision. Years ago, I used an analog meter and 1% was "high accuracy".
Also, a 1K minimum scale is not useful for resistors less than 100 Ohms.
But I would not trust parts from any kind of boutique audio supplier.
Also, a 1K minimum scale is not useful for resistors less than 100 Ohms.
But I would not trust parts from any kind of boutique audio supplier.
I'm talking about the unity used in the video. It is indeed faulty, since the design didn't intend to create an equipment that doesn't work in some scales.@ron68
I am not sure which "unity" you are talking about, it's not only that one and only unit seen in the video, or OP's own unit on the EEVblog thread, the problem is reported by several people, from the comment section under that video one will find a couple more flawed DM858 reported.
It's a bitter repeat of the hope for "cheap" Chinese bang-for-the-buck instrumentation, like I wrote about LCR meters in this post 2 months ago (see the bottom portion), and the EEVblog links posted there.
ps. this is not the full post, it's some limitation with current forum SW as it only shows part of it, click on the post linke to see the whole post.@Sadface fingers crossed!
btw I just discovered by chance some more places where further store info is located on AliExpress, it's really a poor layout nowadays as the store info is spread out at 2 different places and each with their set of info.
One is on the item page, on the right side while hovering with the mouse over 'Sold by' on the upper-right side a drop-down window appears, pic below:
Click on 'Sold by' and it takes one to the stores homepage, there in the upper-left corner hover-over with mouse cursor on the store name and a drop-down window appears...
During last autumn I did look after a better function generator, but after looking up several models on EEVblog so many came out having some annoying bugs, I think my narrowed down search came to the conclusion Hantek HDG3000B Series 16 bit generator seemed Ok, but so far too few posts and I may have to redo my research on it, time will tell.
If this issue is recurrent, as you pointed out, then it is a quality control problem and, sure, may steer you away from buying this model or brand.
If you have the budget and sales availability in your region, equipment produced or at least designed and with production under control of Japan, Europe and US are better.
I use a simple Hantek oscilloscope (assembly by a local brand in Brazil) that works fine. It is a limited performance equipament but it is not faulty.
Everything works within the limits of an entry level chinese equipment (trace sometimes offset from 0V, 8-bit, etc).
But meets my needs and I know what I expect when measuring things.
Using just two leads of a multimeter can cause measurement errors when reading very small resistances because the lead resistance and the two contact point resistances add up to significant error. You need t use a meter with 4-wire (kelvin) capability to make accurate measurements in that very low resistance setting. Two of the 4 wires source a constant calibrated test current, and wire/contact resistance does not affect that unless the resistance is so high that the current source goes into compliance limiting. Those 2 wires source the test current to the DUT (Device Under Test). The other two wires read the voltage across the DUT caused by the test current. Since the voltmeter section of the meter has very high input resistance (often 10 megohms) that is huge in comparison to the voltage sensing test lead wire resistance, so wire resistance simply does not enter in to the reading accuracy at all. The meter sources the current, reads the voltage, and spits out a calculated resistance using Ohm's law. Meters with kelvin capability are not that common especially in a handheld type, and tend to be expensive.
That is the intention. If the value is close to half, the resistors have the wrong value. If the error is the same in absolute sense, the error is in the cables or the meter. It is a great tip actually.