Design a New Precision LCR Tweezers with Much Lower Cost 【Shannon Tweezers ST42】

[TheDefpom]

There is your mistake, you are assuming it is referencing a silicon device, it could be a schottky of FET based device, like I said it is your understanding that is wrong.

[Grandchuck]

What am I missing?

[ebastler]

You can not answer them, I'm no longer interested in your opinion.

In this thread you have interacted with four different users so far (today, and in your earlier attempt a couple of weeks ago). It seems that none of us met your high standards. Maybe you should just give up on posting here?

[ebastler]

ebastler, it's not up to you to decide. Do you have anything to say on the merits of the issue?

Sure, I did not intend to decide, but give you advice.
I won't comment on the "issue" you perceive.

[KungFuJosh]

Do you have anything to say on the merits of the issue?

Please pardon my ignorance, but can you explain what you consider an issue?

So far, from what I can see, you've described two manufacturers as stating different specs for their respective tweezers. Or rather, the same specs 2 different ways. I don't see why that's an issue, as you can determine which device suits your testing needs (as it really comes down to semantics - Vpp vs Vrms - both values can be measured for both devices). I don't have the other device, but my ST-42 lives up to the stated specs (see attached). The ST-42 has also performed very well when compared with significantly more expensive LCR meters (including the TH2830).

So what's the issue exactly?

Thanks,
Josh

[KungFuJosh]

Once again I will try to explain, although the meaning of the question (and not the problem) in terms of the level of the ST-42 test signal was clear from my previous message.
Test levels signal ST-42 -     0.1Vpp(0.033Vrms),0.5Vpp(0.18Vrms),1.0Vpp(0.35Vrms).
Test levels signal LCRPro1 - 0.56Vpp(0.2Vrms),1.4Vpp(0.5Vrms),2.8Vpp(1.0Vrms).
Do you see the difference in the levels of the signal or are they the same for you?
For what reasons the manufacturer LCRPro1 chose these signal levels, I showed in a quote from his manual.
Do you understand this quote in English?
Now the question is - for what criteria and reasons did Shannon choose the test signal level for ST-42? Do you understand this question?

Clearly only @Shannon can answer that question. I still don't see why you're making such a big deal about it. Let me state this again clearly, and see if it makes sense:

Two manufacturers created two different products, at two different price points. Both of them stated their specs. One of them costs ~$100, and the other costs more than 3 times as much. Are you expecting their features to be identical? Do you expect their manufacturers to share the same opinions?

While we're at it, I guess you could email Sourcetronic or Tonghui and ask why they bothered to make the $2000 2832 model LCR have testing as low as 20mVrms as an option?

[KungFuJosh]

Funny question. Why can't a product costing ~$100 have the same characteristics as a product costing ~$300? Moreover, it is quite easy to do for the author of the goods.

That's a funnier question. Why doesn't my $100 tweezers have all the characteristics of my $2000 LCR Meter?

As I mentioned, the ST-42 works exceptionally well, and not just for the price either. I'm happy with its performance.

You should wait for @Shannon to answer what their opinion is on the matter. It's a well thought out device, I'm sure they have a reason.

[TheDefpom]

Indman you certainly do seem to be a troll here, I’ve explained in more than one way, just because you refuse to listen doesn’t make any of us wrong.

I’m not wasting any more of my time with you,

A moderator needs to kick you out because the only thing you seem to be doing is annoying everyone.

[KungFuJosh]

As I mentioned, the ST-42 works exceptionally well, and not just for the price either. I'm happy with its performance.

I completely agree with you on this! And I like the way the ST-42 works. But if I see that the product can be improved in terms of performance and correct some errors that are found during operation, then why not?

Sure, Shannon has been great about correcting errors and improving performance. However, you haven't shown any errors or performance issues. You've only shown that another product has a different opinion.

Do you have any examples showing errors related to this? If you report a bug or some kind of error, then that would be easier to work with than two different arbitrary sets of specs without a specific goal.

[ono]

Actually I am now also curious why Shannon decided to use Vpp instead of Vrms. Why? Because first I also did not pay attention that it is Vpp, and I thought/assumed it is Vrms as everywhere else!

I checked devices that I own or owned, and also some well known other models and they all use Vrms levels - 4284A, U1732C, DE-5000, UT622, ET432, MS8911 and finally ST5S.

One can argue that Vpp is easier to tell whether the signal will activate logic and get through diodes, assuming Vf<Vpp/2. But on other hand if everyone uses Vrms, it would be much much safer to use and display Vrms. Unless there is a very good reason, I find breaking the conventions pretty weird (irresponsible?) move.

Right now knowing 0.1V is actually 0.1Vpp(0.0353Vrms), this level seems to me bit of a quirk/overkill than a useful one. I'd expect 0.1Vrms(0.283Vpp) should be low enough to prevent any semiconductor (Vf>0.142V) to pass the signal, allowing decent and safe in-circuit passive component measurement. But I am still learning - as long as I am alive 

Thoughts? 

[KungFuJosh]

I find breaking the conventions pretty weird (irresponsible?) move.

It's our own responsibility to read and understand spec sheets.

Right now knowing 0.1V is actually 0.1Vpp(0.0353Vrms), this level seems to me bit of a quirk/overkill than a useful one. I'd expect 0.1Vrms(0.283Vpp) should be low enough to prevent any semiconductor (Vf>0.142V) to pass the signal, allowing decent and safe in-circuit passive component measurement. But I am still learning - as long as I am alive 

Thoughts? 

If I had to guess, I would assume that the lower voltage (ie. Vpp vs Vrms) is to prolong battery life, or work with a lower voltage source or something to that effect. But like I said, I'd prefer to hear what @Shannon's actual opinion is.

Besides that, as I mentioned previously, my 2832 LCR meter goes down as low as 20mVrms. There has to be a reason to have that option. Not that I know what it is. 🤣

[thm_w]

Some logic level FETs will have a Vgs threshold down to 0.4V (SSM3K56FS), maybe less. So the 1Vpp could trigger that, if that even matters.
Don't really see what the concern is about, if I have a few voltage ranges to choose from, its all good.

Besides that, as I mentioned previously, my 2832 LCR meter goes down as low as 20mVrms. There has to be a reason to have that option. Not that I know what it is. 🤣

Scientific experiments maybe:
https://ieeexplore.ieee.org/abstract/document/5233800
https://pubs.acs.org/doi/abs/10.1021/acsanm.1c01326

Can find stuff that runs down to 60mV.

[points2]

Hello,
I just picked up in my letter box a Shannon Tweezer (basic model, no leather or golden plated version  ; so far so good, I only charged it up, not tested)

Firmware is => 1.4.4

Question => do we get extra-features / special gifts / any VERY cool extra-stuffs (discount on MXO4 from R&S ? would be cool) by upgrading this 1.4.4 firmware ?
If yes, which one(s) ?

I just ask because I don't feel confident to perform the upgrade... I see I need to use some "commands"...  I feel like I'll screw up... 
I'm not a newbie in electronics (although sometimes I'm wondering if I know anything about e-    )
but the software stuff is really something I find "uninteresting"... and my brain is like "off" when it's about software... only "on" when it's about hardware (sometimes...)

I stop joking => my concern is =>
- I will use the LCRmeter mainly as LCR meter (basic), and 95% as "C" meter
- I don't care about dead fine precision, if firmware upgrade acts on that... simply because I use only SMD capacitor, which a capacitance margin (by manufacturing) of few % to 20% vs nominal capacitance

THks & Rgds

[tautech]

Hello,
I just picked up in my letter box a Shannon Tweezer (basic model, no leather or golden plated version  ; so far so good, I only charged it up, not tested)

Firmware is => 1.4.4

Question => do we get extra-features / special gifts / any VERY cool extra-stuffs (discount on MXO4 from R&S ? would be cool) by upgrading this 1.4.4 firmware ?
If yes, which one(s) ?

I just ask because I don't feel confident to perform the upgrade... I see I need to use some "commands"...  I feel like I'll screw up... 

Improvements are listed here:
https://shannontweezers.github.io/docs/upgrading-firmware/

However there's a catch that you need have CH340 drivers installed on your PC to install the firmware....something Shannon has overlooked as many of his customers don't.

This is by no means an authoritative reference but will give you an idea of what's involved:
https://electropeak.com/learn/how-to-install-ch340-driver/

I've not cracked it yet for Win10 Device Manager to identify Shannon's tweezers as a USB CH340 device and assign a Com port to them.
Windows thinking it knows best will assign a generic driver to a USB device and then the fun starts as good luck telling Microsoft you know better. 

Currently I see this as a major/serious failing of the device and something Shannon needs either change or provide detailed and failsafe methods of 100% reliable USB connection.
This is not obviously apparent to Shannon as he needed CH340 drivers right from early development stages whereas until a week ago I never knew what they were.

Maybe the great community here can offer Shannon and some of us unable to upgrade these nice ST42 tweezers with a simple solution.

[KungFuJosh]

I just ask because I don't feel confident to perform the upgrade... I see I need to use some "commands"...  I feel like I'll screw up... 

You'll be okay. 😉

Hold the joystick in the up position like in the video while you plug in the USB cord:

Then follow the easy to read instructions on this post: https://www.eevblog.com/forum/testgear/design-a-new-precision-lcr-tweezers/msg4922464/#msg4922464

I've not cracked it yet for Win10 Device Manager to identify Shannon's tweezers as a USB CH340 device and assign a Com port to them.

I had no issue on Windows 11, so Windows 10 should be easier. 😉 I'm not sure why Windows didn't select the right driver for you, it's usually automatic with this.

Try these instructions: https://learn.sparkfun.com/tutorials/how-to-install-ch340-drivers/all

My suggestion would be to uninstall whatever incorrect driver Windows tried to install. Then follow the install directions for the CH340.

[ono]

I find breaking the conventions pretty weird (irresponsible?) move.

It's our own responsibility to read and understand spec sheets.

Agreed. Everyone should read and understand spec sheets and manuals - my lazy self included. All I want to say here is that displaying 1V for AC signal but meaning 1Vpp seems as great as using m/s for car speedometer. You can put it on spec-sheet but this is still asking for a trouble. This case is absolutely benign, but eventually we get mishaps like NASA's Mars Climate Orbiter. So again I am mostly curious if there was a good reason for Vpp instead of Vrms here, nothing else.

Scientific experiments maybe:
https://ieeexplore.ieee.org/abstract/document/5233800
https://pubs.acs.org/doi/abs/10.1021/acsanm.1c01326

Can find stuff that runs down to 60mV.

Alright, some good reads there. Thanks! This makes ST42 0.1Vpp future proof for some passive components measurements with bilayer graphene tunnel field-effect transistors in circuit   

[tautech]

I've not cracked it yet for Win10 Device Manager to identify Shannon's tweezers as a USB CH340 device and assign a Com port to them.

I had no issue on Windows 11, so Windows 10 should be easier. 😉 I'm not sure why Windows didn't select the right driver for you, it's usually automatic with this.

Try these instructions: https://learn.sparkfun.com/tutorials/how-to-install-ch340-drivers/all

My suggestion would be to uninstall whatever incorrect driver Windows tried to install. Then follow the install directions for the CH340.

Respectfully Josh it not need be this hard.

I strongly suspect those that have no problems with a ST42 firmware install already have a CH340 driver install already on their PC, say for instance those that muck with Arduino and such.

For us that have issues we need a simple set of solutions;
1. To remove any incorrect device association our PC has with ST42
2. A recommended driver install package available from Shannons website
3. Simple to follow steps for successful PC connection for firmware updates.

Simple, how simple;
Dad our tweezers have a new FW update available
Good spotting son, download and install it for me please

Until we have such, we won't be marketing ST42 in NZ.

[KungFuJosh]

Simple, how simple;
Dad our tweezers have a new FW update available
Good spotting son, download and install it for me please

I agree that it should be easier, but I was trying to help you out. 😉

I'm not an arduino guy, and have nothing like that. The drivers installed when I plugged in the ST42. Maybe try plugging it in normal first, then after drivers install, try going into firmware update mode.

I assume they'll eventually have a GUI/visual installer for the firmware, but I don't know that obviously. It's a pretty simple thing to have an installer run an exe from a prompt. The larger issue is dealing with security certificates, which can be both expensive and a pain in the ass.

I definitely agree they should have a download link for the appropriate drivers. Even though they should auto install, that doesn't mean they will for everybody. I had similar issues with high-end (i.e. expensive) sound cards that were supposed to auto install their drivers also. I was lucky to get drivers for when that didn't work right. Sometimes, it's Windows fault for not updating some BS registry or something I can't remember. In any case, it definitely helps if the manufacturers keep drivers available.

It's probably also good to keep in mind this is still a fairly young product. Most of the people that received them were probably considered "early birds."

[tautech]

Simple, how simple;
Dad our tweezers have a new FW update available
Good spotting son, download and install it for me please

I agree that it should be easier, but I was trying to help you out. 😉

I know and it's appreciated however when you try to get a COM port to automatically identify a CH340 device on four, yes 4 W10 PC's and none can you know there is a problem with ST42 that needs much improvement.

I look forward to a simple solution from Shannon. 

[KungFuJosh]

when you try to get a COM port to automatically identify a CH340 device on four, yes 4 W10 PC's and none can you know there is a problem with ST42 that needs much improvement.

I look forward to a simple solution from Shannon. 

If you do something wrong the same way 4 times, why would you expect different results? 😉

A link on their website with an "install this first" line might be helpful.

[tautech]

when you try to get a COM port to automatically identify a CH340 device on four, yes 4 W10 PC's and none can you know there is a problem with ST42 that needs much improvement.

I look forward to a simple solution from Shannon. 

A link on their website with an "install this first" line might be helpful.

No, that's not enough and late as I guess it was in USA when you typed that post it is obvious you didn't think that through.

Dunno about you but at my bench is only one USB source to charge the ST42 a PC and the instant it's connected W10 says it's not recognised albeit ST42 is not in FW mode.
Shannon needs find a failsafe solution.

[ebastler]

Simple, how simple;
Dad our tweezers have a new FW update available
Good spotting son, download and install it for me please

Yeah, that's how my parents handle computer updates too. 
Have you actually tried asking your son? That might work...

[tautech]

Simple, how simple;
Dad our tweezers have a new FW update available
Good spotting son, download and install it for me please

Yeah, that's how my parents handle computer updates too. 
Have you actually tried asking your son? That might work...

Yeah right. 

[KungFuJosh]

No, that's not enough and late as I guess it was in USA when you typed that post it is obvious you didn't think that through.

Dunno about you but at my bench is only one USB source to charge the ST42 a PC and the instant it's connected W10 says it's not recognised albeit ST42 is not in FW mode.
Shannon needs find a failsafe solution.

I disagree, but let me put it this way. My TH2830 LCR (not at all a new product), that costs 10 times the ST42, has a USB driver listed on their website. That USB driver was rejected by Windows, and I had to force install it (good luck if you don't know how to do that). It still doesn't do anything for me yet, but at least it's listed in Device Manager now.

When it comes to firmware, you have to email Tonghui to request firmware, and they ignore all fw requests. They're the absolute worst about communication and support, despite making nice hardware. Sourcetronic has their branded version of the same devices, and significantly better support. You still need to email them to request the firmware, and then figure out how to install it. It's not that bad because there's a USB port on the front panel, but that's obviously not an option here.

So you can spend $2000 on a TH2832, and be ignored by the manufacturer when you want to update your firmware or access it from your PC. If you want the tweezer fixture, that's the Tonghui TH26009B for another $200.

Or you can spend $109 on a nice LCR Tweezers from somebody that is responsive and supportive of their product, despite that it's still in its infancy. You might need to ask somebody for help installing a driver - which should automatically install - but clearly doesn't always. That's more a failing on Windows part than the tweezers, but obviously effects the tweezer support.

[Shannon]

Hi all,

Let's discuss why we use these excitation voltage, we are late .

First of all, we need to admit that many capacitance measurements do use 1Vrms as the test standard in the data sheet.
This value looks accurate, but it's not that accurate. Because there is usually a resistor connected in series between the excitation voltage source and the DUT, at this time the real voltage on the capacitor is related to the capacitance value and the series resistance.

Imagine if there is no series resistor, a 1000uF capacitor, superimposed on a 10kHz, 1Vrms signal, the current will be 62.8Arms, which is ridiculous. (If I am wrong, please help me point out). So I think that 1Vrms is not so strict sometimes, Especially for those capacitors whose capacitance is above 1uF.

But the RMS value is more suitable for the expression of energy, and the Q value is the ratio of energy.

One of my impression is that capacitors that require high excitation voltage often do not require high precision. I don’t know if it is accurate. If there is a more correct expression, please correct me.

Another point is that using a higher excitation voltage can obtain a higher signal-to-noise ratio, which is very meaningful for those measurement systems with a large noise floor, in this situation, higher SNR means the measurement can be more accurate, but it is not very meaningful for ST42, the noise floor of ST42 is very low.(you can verify the measurement results of 0.1Vpp, 0.5Vpp and 1Vpp, the difference is very small, higher voltage does not bring higher accuracy).

ST42 is a very small portable device, too high excitation voltage will consume more power consumption.
Another point is that we need more complex circuits (default operating voltage 3.3V) in order to achieve 1Vrms (2.8Vpp), and may introduce high noise(boost type switch power), we think the gain is not very big.

The first impression of ST42 for users is that it is suitable for measuring SMD components, because it is in the form of tweezers. When measuring on PCB, the most noteworthy thing is whether the excitation voltage will cause errors due to excessive excitation. The user's intuitive experience of Vpp must be clearer and more direct than Vrms.

The last question, why do you need 0.1Vpp and 0.5Vpp? I understand that 0.25V is a relatively marginal voltage value. There will be leakage current of some devices at this voltage that will affect the measurement accuracy, and it does not have to be completely turned on. (0.3V for Schottky diode and 0.7V for silicon diode in the book) will affect the measurement. From this point of view, as long as the measurement accuracy is not affected, the smaller the voltage is, the safer it is.

I don't know that if this reply would stop the argument. I suggest that everyone communicate calmly, because only through calm discussions we can discover more details hidden behind ST42 and the valuable content behind them