Shannon ST42 LCR Tweezer Test and Comparison Thread

[tautech]

In the meantime, I had taken a look at Shannon's website.
But it doesn't say much about the ST42, I would have expected more technical details.
The accuracies given there are sufficiently low for C and L, but for R it could sometimes be too much for precision resistors.
However, these would be exceptions, before we get too excited.
The website was last updated in 2022, the corresponding firmware available there is also 2 years old, there was probably nothing more to improve.
Although I ordered the ST42 later than the ET4510, I assume that it will arrive sooner because customs formalities are no longer necessary.

Yet Shannon invites us to join the ST42 discussion on EEVblog where the OP was updated: Last Edit: May 06, 2024, 03:06:27 am by Shannon

In this thread Josh updated to fw v1.5.4 early June but it seems there is not a website link to it. 

Josh, how did you source fw v1.5.4 ?

Not that it worries me as the units I have coming will all have this FW installed.

[KungFuJosh]

In this thread Josh updated to fw v1.5.4 early June but it seems there is not a website link to it. 

Josh, how did you source fw v1.5.4 ?

Not that it worries me as the units I have coming will all have this FW installed.

Using the OTA firmware update tool, it will automatically pull the latest firmware if you don't specify a version. You need to open a command prompt or shell, then do updaterfilename COMport and it will run the update for you. I renamed it to fwu.exe so I did .\fwu.exe com8 for my tweezers.

I'm also likely to sell the ST42 to the US market directly, but if/when that happens, I will do a firmware update and quick test on his test board before shipping tweezers out to make sure nothing is defective.

[Martin72]

It finally arrived today, picked it up earlier.
Nice and small, you can't say otherwise.
The build quality, however, is rather... "robust".
You shouldn't look at it very closely, the opening for the display, for example, looks as if someone has nibbled it out.
But as is almost always the case, it's the inner values that count and I'll be testing them out soon.
First at home and against LCRs, which are here.
"Unfortunately" I'm on vacation now, so a test against calibrated devices will take some time.
But that won't stop me from posting the results of the home tests beforehand.
I'll fully charge the ST42 for now...
Oh yes, there was a note saying that some spare screws/tips were "hidden" in the case, I didn't find any of them.

[TomKatt]

I just received an email indicating that my order has been delivered to my post office box awaiting pickup on my way home this afternoon :-)   I placed my order on 6/17, so shipping to the US was much quicker than I expected.  I do not order from Aliexpress very often - didn't really expect any problems but very happy with how smoothly the order went through.

Very excited 

[KungFuJosh]

I received my new test PCB. I'll have the parts order in on Monday, and then I'll run a bunch of tests too. Including the ST42, ST2832, and probably also my Siglent bench DMMs. Maybe also the DE5000.

[Martin72]

The display looks good, OLED is simply hard to beat.
The information about charging is also nice.

[Martin72]

I received my new test PCB. I'll have the parts order in on Monday, and then I'll run a bunch of tests too.

This would be a good opportunity to have your TH2832 calibrated.
If its basic accuracy (0.05% is excellent, it could hardly be better) is confirmed, you can measure your board and the values determined would then actually have reference status, as your other LCRs are clearly above the accuracy of the TH2832, especially the ST42.

[KungFuJosh]

This would be a good opportunity to have your TH2832 calibrated.
If its basic accuracy (0.05% is excellent, it could hardly be better) is confirmed, you can measure your board and the values determined would then actually have reference status, as your other LCRs are clearly above the accuracy of the TH2832, especially the ST42.

I think my ST2832 cal hasn't expired yet. I don't really know where I would send it for calibration anyway when the time comes...which will also be based on the test board to see if it still agrees, or drifts too much. I don't really have a need for a certificate beyond saying that it has a certificate on here. 😉

[Martin72]

I think my ST2832 cal hasn't expired yet.

You had turned your 2830 into a 2832, so there is no longer any question as to whether.

which will also be based on the test board to see if it still agrees, or drifts too much.

You take the trouble to design a test board and equip it with components that have a value and a tolerance.
This means that the respective value can vary, and if you are unlucky it will be out of tolerance.
To be able to determine this properly, you need a measuring instrument of which you know where its own tolerance lies.
And this must be documented.
Factory calibrations are not to be trusted at first, if you want to use a device as a reference, you should have it "neutrally" calibrated.

I don't really have a need for a certificate beyond saying that it has a certificate on here

Then you don't need to buy a measuring device, which is very accurate according to the manufacturer's specifications; a guessing tool will suffice.
Now seriously.
I buy brand A because it's supposed to be accurate, but I'm not really interested in whether it's really that accurate, the main thing is that it shows something I expect.
I may see it too narrowly, because I have been checking things professionally for over 20 years and have to provide corresponding proof that everything is correct.
Either way, it's not my thing.
My problem, no question.

[KungFuJosh]

Sure, but I could get the ST2832 certified...if I knew where to have it done. Or I could have my test board certified. Or both. But either way, I don't know where to have it done. I'm also not willing to spend $500 for certification of either.

I think my ST2832 cal hasn't expired yet.

You had turned your 2830 into a 2832, so there is no longer any question as to whether.

I get what you're saying, but that was not really different than a firmware update. Most home users don't recertify with every firmware update. 😉

[Martin72]

Your measurement frequency has doubled, the calibration referred to the maximum frequency before the "upgrade".

if I knew where to have it done. Or I could have my test board certified. Or both. But either way, I don't know where to have it done. I'm also not willing to spend $500 for certification of either.

I don't know your situation in the states, but I have easily 4...5 calibration laboratories in the vicinity.
I had my Brymen 869S calibrated for 79€, my SDM3065X would cost just under 150, an LCR meter a little over 100.
A recalibration of my DMM Check Plus Board also costs 79€.
If the ET3502 convinces me, I will definitely have it calibrated, I'm still thinking about the ST42, depending on whether it convinces me too.
A first R measurement earlier was rather sobering.

[KungFuJosh]

You're lucky then. Trescal is who SiglentNA prefers for real cal, and they're not cheap, or local to me. The closest is at least a couple hundred miles. So then there's shipping costs added to it.

There are possibly a few others in my state, but nothing less than about an hour drive.

Basically, if I don't see any indication of issues, I probably won't waste any time or money on it. If 5 meters agree on a bunch of 0.1% resistors, that's probably good enough.

ETA: I emailed a couple labs in my state to see what their rates and capabilities are. I'd be impressed if they come back with anything reasonable. 😉

[TomKatt]

I'm just a simple hobbyist, so 'real' calibration is beyond my budget - the best I can hope to attain is reasonable accuracy achieved by purchasing what I perceive to be the most reliable tools combined with some common sense of the readings I get and comparing those results to any other gear I have.

Anyhoo, I just recieved my set of ST42 Tweezers and my initial impressions are excellent - these tweezers look and feel like a high quality tool.  They have just enough weight in the hand so they don't feel 'cheap', yet not so much as to be unconfutable using them.  The oled display is excellent - very sharp and readable.  Despite the small screen size there is a lot of information and it is easily read at board distance.  The Hold function works well, but that setting seems to reset every power cycle?  I'm still learning the menu system, which although is easy to use does have a lot of options.

I did order the optional curved blade tips, but now that I have the tweezers in my hand I'm not sure if I really needed them.  There was a note in the box indicating that the tips and a set of spare screws were inside the case.  But in the excitement of receiving the package at the post office I could not resist opening the box in my car - I may have lost the screws in that process...  The tips were wedged between the foam and case side, but I did not find any screws - I only see one small plastic insulator type bead...  I'm not sure if I lost parts or if that insulator is needed - the tips that came attached to the tweezers do not appear to have this insulator on the screws.  Not really a huge deal, but it would be nice to have a list of all the parts in the kit so I could verify everything was accounted for.  A photo attached below shows the insulator bead - if anyone else knows what that is for I'd be appreciative.

The calibration board is nice - both as a learning tool and also a sanity check for readings.  I haven't had a lot of time to play around with calibration, but as a first pass out of the box every component on the calibration board measured within a fraction of 1%.  Again, I have nothing to validate those results at this time but they do seem reasonable.

All in all I am very happy with this purchase - while I don't do a lot of smd work these are still very helpful for boards stuffed with components and are a lot easier to use than test probes in those cases.

Edit - forgot to mention that my purchase was motivated by the desire to obtain an LCR type meter to add to my bench.  I considered the DE-5000 that seems widely respected, but these tweezers looked to provide much of that functionality while also being useful for work on cramped boards.  Also, I got the sense that the DE-5000 tweezers were lacking and everyone seems to be hacking togther some kind of Kelvin clips for that meter...  I figured why noyt just get smart tweezers instead?

Edit 2 - In addition to a list of parts included in the package, it might be helpful to enclose any optional small parts (tips, screws, insulators?) in a small bag or similar package so they are not loose in the case.  The tips aren't likely to go far, but if there were screws inside my case they are the size of a grain of rice and very easily lost...

[Martin72]

I held the tweezers to the inductances of the DMM Check plus earlier.
There are probably some problems with small inductances, see 1µH and 10µH.
I then activated the self-calibration, the -1.3µH then becomes 1.2µH.
With the 8.1µH the "correct" value of 10.4µH.
100µH and 1mH agree well.

[Martin72]

After I calibrated again (open/short) and ran the selfcal routine as before, the results are as follows.
(10kHz, 0.5V) (ref)
Inductance:

1.12µH (1.061µH) +5.5%
10.56µH (10.52µH) +0.4%
104.0µH (104.3µH) -0.3%
1.040mH (1.032mH) +0.8%

Capacity:

1.019nF (1.019nF) 0
10.16nF (10.16nF) 0
102.3nF (102.5nF) -0.2%
1.037µF (1.001µF) +3.6%

Resistance(RDC):

99.98 Ohm (100.058) -0.6%
998.5 Ohm (999.4)  -0.1%
10.00kOhm (9.9995k) +0.01%
100.0kOhm (100.017k) -0.02%

Apart from the two clear slips, these are very good results for a device of this simple design.
The fact that it is better to calibrate it beforehand makes it clear that you can't just use it quickly if you want to rely on the results.
But then you can trust the measurements almost blindly, and the fast display is also pleasant.

[KungFuJosh]

I wonder how much of an effect aging has with these. My tweezers are over 2 years old. I'm looking forward to my new comparison this week.

[Martin72]

If you want to know exactly, you would have to access the objects you measured 2 years ago with the tweezers and measure them again.
But you can start again now and then every 6 months....
The accuracy of the ST42 is not outstanding, rather worthy of the price, but in practice this should hardly play a role.
Even the 5.5% deviation at the smallest L value is hardly relevant in my opinion, even if it far exceeds the tolerance specified by the manufacturer.

[KungFuJosh]

I was more referring to my measurements being closer to the bench LCR. Stuff should arrive today for the test PCB, we'll see how it all looks.

[KungFuJosh]

I forgot how tedious these cal tests are. Here's a PDF with the results of the ST2832 and ST42. On the bright side, my estimates for calculating dissipation factor were pretty darn close.

I decided against making it take twice as long and including other meters. In the future, if I make a LCR test board that I really like, I'll get it calibrated and then do one test with all my LCR meters. I need to devise a better way to connect the kelvin clips, it's very picky about position.

EDIT: Corrected test voltages on PDF.

[Martin72]

I have downloaded it and I have questions about it....
But late, now I'm too tired, time for bed.

[KungFuJosh]

It's definitely past your bedtime!

[Martin72]

I have downloaded it and I have questions about it....

More than this thread can cover...
Maybe we should discuss the rest somewhere else, maybe in the ST2830 thread.
But three things after all:
-Why did you enter the output voltages for the ST2832 and ST42 differently, in Vrms for the ST2832 and in Vpp for the ST42?
-Why did you not use frequencies below 1kHz for the inductances, at least for the larger coil values it would have been permissible.
-And the third, measuring coils in the higher mH range at 100khz or more, hardly makes any practical sense.
But it's nice to see that the ST42 can still keep up with the capacitors, I've noticed that too.

[KungFuJosh]

More than this thread can cover...
Maybe we should discuss the rest somewhere else, maybe in the ST2830 thread.
But three things after all:
-Why did you enter the output voltages for the ST2832 and ST42 differently, in Vrms for the ST2832 and in Vpp for the ST42?

Because that's how each device is specified. 1V on the ST42 is 1Vpp, and on the ST2832 it's 1Vrms.

-Why did you not use frequencies below 1kHz for the inductances, at least for the larger coil values it would have been permissible.

My tests followed the calibration chart that came with your ST2830. Your cal only showed testing inductance at 1kHz, so I added the others for fun. I did expand on a few areas to see what the devices could handle, but my tests covered at least what the original cal cert did, except that I changed values to simple 1, 10, 100 for each range (in resistance) rather than the other seemingly arbitrary intermediate values. If you want me to cover something else specifically, let me know and I'll add it before I do my 5th (and hopefully final) version of the test board.

-And the third, measuring coils in the higher mH range at 100khz or more, hardly makes any practical sense.

Practical sense or not, that falls in the 1% accuracy range at worst according to their chart. Why not push a little and see how well it works?

But it's nice to see that the ST42 can still keep up with the capacitors, I've noticed that too.

Indeed, the ST42 did quite well across the board. I was surprised by the few failures testing at 10kHz, but I don't know what the ST42 is supposed to handle. Hopefully Shannon can release some more detailed specifications.

I'm happy to discuss this further wherever you like. 😉

[Martin72]

Hi,

Because that's how each device is specified. 1V on the ST42 is 1Vpp, and on the ST2832 it's 1Vrms.

This can be converted accordingly, one into the other or vice versa.
Two different units make it difficult to compare them at first glance.

My tests followed the calibration chart that came with your ST2830. Your cal only showed testing inductance at 1kHz

Oh, is that so?
Then I'll have to have another serious word with the calibration laboratory.

Practical sense or not, that falls in the 1% accuracy range at worst according to their chart. Why not push a little and see how well it works?

This was not meant in the context of the accuracy of the LCR.

I was surprised by the few failures testing at 10kHz, but I don't know what the ST42 is supposed to handle.

In this regard, I would exhaust the calibration possibilities of the ST42 before the measurements, if you have not already done so.
Unfortunately, this is unavoidable as soon as you change the measuring frequency, even with the ST2830, if you want to know exactly.

If you want me to cover something else specifically, let me know and I'll add it before I do my 5th (and hopefully final) version of the test board.

I think the idea of a test board is very good, I had already thought about it a few times, because the LC option of the DMM Check Plus is a bit too meager for me, apart from the fact that normal components were installed there, which were only measured.
In this respect:

I'm happy to discuss this further wherever you like.

If you (or I) would start a dedicated thread via a testboard.

[KungFuJosh]

I think the idea of a test board is very good, I had already thought about it a few times, because the LC option of the DMM Check Plus is a bit too meager for me, apart from the fact that normal components were installed there, which were only measured.
In this respect:

I'm happy to discuss this further wherever you like.

If you (or I) would start a dedicated thread via a testboard.

Hmmm, I definitely should have corrected the voltages. I was too tired when I did that now that I think of it, and both voltages are shown in Vrms. Though the ST42 shows voltages in Vpp on it's display. Since the purpose is to see if the devices are in spec, they should be measured and displayed in the correct method for each device. I should have corrected that. I will. Thanks for pointing that out.

I don't want to exhaust the cal abilities of the ST42 on my own. I would like Shannon to specify what it should be capable of at each frequency, and use the test to confirm that. I can't know if it's out of spec without specs.

I would definitely like to discuss the board more before I make another version. It's pretty close, but I need some advice I think on a couple things.

Thanks,
Josh