Shannon ST42 LCR Tweezer Test and Comparison Thread

[Martin72]

Hi,

LCR measuring tweezers, to which the greatest things are attributed, as the sole miracle tool that makes other LCR superfluous, where some people never tire of bringing them into play in every purchase advice....something like that makes me curious in principle.
So I bought one from Aliexpress and it should arrive next week.
In addition to an incoming inspection in terms of appearance and manufacturing quality, the main component will of course be measurements.
I have thought of the following steps:
- Measurements on the DMM Plus Check reference, more precisely on its LCR option.
- Comparative measurements with the following devices:
Mastech LCR tweezers
ET4410 Benchtop LCR Meter
ET4510 Benchtop LCR Meter
Sourcetronic ST2830 Benchtop LCR Meter, calibrated
Agilent U1733C Handheld LCR Meter, calibrated.
GWInstek Milli-Ohm Meter, calibrated.
- Comparison measurements on components that are already integrated in a circuit.
- Comparison measurements cold start/ after a warm-up time.
The latter because it was said that with other devices you have to wait until they meet the tolerance.
I maintain that it doesn't matter.
We'll see.
Furthermore, an attempt to see what maximum component size can still be measured mechanically without using aids such as wire extensions, which of course distort the result.
And one more thing, measurements on coils with a core, if their size allows it.
This could be interesting insofar as the measuring voltage of the ST42 is rather low.
I'm curious to see how it performs.
Why am I opening this thread now?
To collect further ideas, if you think of anything else, post it here.
Next post will follow when the ST42 has arrived.

Martin

[tautech]

I have thought of the following steps:

You missed speed of measurement and speed of use = convenience at the bench for the majority of tasks.

[KungFuJosh]

- Comparison measurements cold start/ after a warm-up time.
The latter because it was said that with other devices you have to wait until they meet the tolerance.
I maintain that it doesn't matter.

I agree, I don't actually usually wait the 30 minutes for the bench meter either, unless it's for something that really matters. Which is rare. 😉

However, you can often finish measuring with the ST42 by the time the bench meter goes from power on to ready even without warmup.

Furthermore, an attempt to see what maximum component size can still be measured mechanically without using aids such as wire extensions, which of course distort the result.

If you leave the wire aids on, you can run calibration with the wires as part of the device to compensate for them...but you already know this. 😉

[Hydron]

I have thought of the following steps:

You missed speed of measurement and speed of use = convenience at the bench for the majority of tasks.

+1 to this - the reason I never pick up my Mastech tweezers isn't due to any inaccuracy etc, it's that they are just so much worse ergonomically and speed wise compared to the ST42. You're not buying standalone SMD tweezers for top end specs, you're getting them for convenience (though obviously the more accuracy the better, and I look forward to seeing the numbers).

[KungFuJosh]

I'll run some new comparison tests soon too. Here's the old result when I still had buggy firmware on my bench meter. The ST42 was very helpful with sanity checks.

[Martin72]

Measuring speed ? Are you in a hurry guys ?

[KungFuJosh]

Yes!

The PCBs with SMT I was building last week had 16 of the same part on each of the 3 boards. I don't want to spend 2 hours measuring 48 of the same component before I could continue testing/installing parts.

[Martin72]

I don't want to spend 2 hours measuring 48 of the same component before I could continue testing/installing parts.

You don't have to....
The warm-up time is to be regarded as a standardization.
An LCR meter may well need 20 to 30 minutes (the more complex the design, the more) to be able to measure within its own tolerance.
But who cares about a basic accuracy of say 0.05% if the components to be measured have a tolerance of 5% or more....
In other words, if it is necessary to select components with an accuracy of 0.05%, then there is something wrong with the circuit.
Or to put it another way, if the ST42 reaches its own tolerance significantly shorter, it is only because significantly fewer circuits have to be thermally balanced.
All theory is gray, it's the practice that counts.

[KungFuJosh]

I don't want to spend 2 hours measuring 48 of the same component before I could continue testing/installing parts.

You don't have to....
The warm-up time is to be regarded as a standardization.
An LCR meter may well need 20 to 30 minutes (the more complex the design, the more) to be able to measure within its own tolerance.
But who cares about a basic accuracy of say 0.05% if the components to be measured have a tolerance of 5% or more....
In other words, if it is necessary to select components with an accuracy of 0.05%, then there is something wrong with the circuit.
Or to put it another way, if the ST42 reaches its own tolerance significantly shorter, it is only because significantly fewer circuits have to be thermally balanced.
All theory is gray, it's the practice that counts.

I know, but you're forgetting two things: 1. I don't have a tweezer attachment for my bench LCR because anything good costs more than the ST42 for me; and 2. I don't want the reduced mobility of being tethered to the bench meter.

So the ST42 works faster, and with better mobility. Also, the regular startup time from powering on the bench LCR to the point that it's ready without warmup is still long enough to be measuring a few components already with the tweezers.

Without the overpriced tweezer attachment, the bench LCR takes hours to test SMT stuff. For the first round of LCR comparison/firmware tests I hadn't designed my test PCBs yet. It literally took hours to mount and test all the SMT components on the SMT fixture. It took minutes with the tweezers.

I'm going to order a new version of my test board so I can also test step dissipation factor now that I know how to do that. I'll share a new comparison when I'm done.

[Cyclotron]

I'm certainly interested in your testing results. Testing and comparing to other devices seems reasonable.

I see folks being given recommendations based on their requirements. People are encouraged to develop or have requirements.
My needs were straightforward. I simply required an instrument to swiftly assess components during repair triage. Based on my experience, I would confidently recommend these tweezers to others with similar needs.

That said, I can imagine there are a lot of objective tests that can be done, and I do look forward to reading the results, but I don't know how that will impact the subjective recommendations that are made to people. Obviously, if you have findings that show a better solution at comparable pricing that fits my needs, I'm all ears.

[Overspeed]

I don't want to spend 2 hours measuring 48 of the same component before I could continue testing/installing parts.

You don't have to....
The warm-up time is to be regarded as a standardization.
An LCR meter may well need 20 to 30 minutes (the more complex the design, the more) to be able to measure within its own tolerance.
But who cares about a basic accuracy of say 0.05% if the components to be measured have a tolerance of 5% or more....
In other words, if it is necessary to select components with an accuracy of 0.05%, then there is something wrong with the circuit.
Or to put it another way, if the ST42 reaches its own tolerance significantly shorter, it is only because significantly fewer circuits have to be thermally balanced.
All theory is gray, it's the practice that counts.

Hello
Accuracy is the result of the sum of the uncertainties so accuracy of a component need to be separate from the accuracy of measuring equipment
There is several use for a LCR or even a ohmmeter

_ Sorting component in the same ''precision quality so reject the extremes values / out of tolerances values
_ Matching components in pair , triple ... as capacitor in parallel
_ Select component to catch the closest perfect nominal value
_ Identify component with out engraving value

A very good test of a Quality setup which include a measuring equipment is to run an ANOVA R&R test 

Regards
OS

[KungFuJosh]

That said, I can imagine there are a lot of objective tests that can be done, and I do look forward to reading the results, but I don't know how that will impact the subjective recommendations that are made to people. Obviously, if you have findings that show a better solution at comparable pricing that fits my needs, I'm all ears.

I've already done comparison tests (which I'll be diving deeper into again soon when I receive my new test PCBs), but the tweezers performed exactly as they're supposed to. I think part of the point is that there really isn't much to compare within the price point. These tweezers are as good better than tweezers that cost 3x as much. They also held their own (and helped correct bad fw) in bench meters that cost 10 to 20x as much.

I think if somebody has some of those overpriced Canadian tweezers to compare to, that would be great.

[BirdManPhil]

Are there any tweezers that can measure caps as low as 0.1pf with a resolution that works for this? I see shannon st42 bottoms out at 0.3 or 0.5 pf

[KungFuJosh]

Are there any tweezers that can measure caps as low as 0.1pf with a resolution that works for this? I see shannon st42 bottoms out at 0.3 or 0.5 pf

I'd be a little surprised, but maybe. Even our expensive bench meters doesn't claim accuracy below 1pF.

[Martin72]

At less than 1pF, you are also more likely to be in the parasitic range where you are measuring something.

[BirdManPhil]

That sucks. Maybe this would be a good complement to the tweezers then
https://www.szmatrix.com/products/digital-lcr-meter?

Am I mistaken or does that seem to have the accuracy I'm looking for?

[KungFuJosh]

Am I mistaken or does that seem to have the accuracy I'm looking for?

Display range and accuracy aren't the same thing. That device is much lower end the the ST2832 I shared the accuracy chart for.

[TomKatt]

That sucks. Maybe this would be a good complement to the tweezers then
https://www.szmatrix.com/products/digital-lcr-meter?

Am I mistaken or does that seem to have the accuracy I'm looking for?

I question the ability to accurately measure the 0.0001 pf stated in that devices spec sheet.

[KungFuJosh]

Agreed, certainly not on that meter.

At 200kHz the ST2832 can measure 10fF (the pF is a typo on the chart in that position top right corner), but that's in it's lowest accuracy range.

[KungFuJosh]

If you want to spend $20,000 on an LCR, you can get into the fF range better, but still probably 5% accuracy at best.

[Overspeed]

Hello

An Hioki online calculator

https://www.hioki.com/e/products/lcr/im_calc_accur/

a IET LCR comparison

https://www.ietlabs.com/basic-accuracy-of-an-lcr-meter

I am not an expert in LCR but in all test equipment price follow the performance .

[KungFuJosh]

According to Hioki's Range chart (not accuracy) they have very limited coverage below 1pF on the IM3536, which appears to be their best option currently.

[BirdManPhil]

Do I have to spend 20k just to test a 0.1uf cap though...

[tautech]

I think part of the point is that there really isn't much to compare within the price point.

There is but they are junk.

These tweezers are as good better than tweezers that cost 3x as much. They also held their own (and helped correct bad fw) in bench meters that cost 10 to 20x as much.

This ^

I think if somebody has some of those overpriced Canadian tweezers to compare to, that would be great.

I have.
ST3 that are nearly 20yrs old < now retired in favour of the far better ST42.

A ST5 variant has regularly been of interest as a replacement to ST3 but not at that price. 

[Martin72]

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.