Design a New Precision LCR Tweezers with Much Lower Cost 【Shannon Tweezers ST42】 - Page 1
Forum section: electronics / testgear

author: Shannon
author_rank: Frequent Contributor
timestamp: February 20, 2021, 04:39:53 pm
content: Shannon Tweezers Calibration Process2021/12/30---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------This video is to demonstrate the calibration process of Shannon Tweezers, which is easy to conduct through three steps.you can observe how accurate and precise through this video.Hope you like it.Menu and ABS case Image Update2021/10/05---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------The unboxing Shannon Tweezers video is coming.Forgive my poor English and video cut techHope you like it.This video content includes1. the Container for the Tweezers2. The ABS Case and Tips teardown3. Accuracy Presentation4. Hold Function and shortcut5. Oscilloscope and Shannon Tweezers test each otherIf you have any questions, please feel free to let me know.Thanks for your suggestions and supports, we will be there.2021/10/04---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------About a year ago, a friend discussed an AC impedance measurement scheme with me, we think this scheme can meet most of the testing requirements. Then we started to cooperate to discuss the possibility of a more practical LCR tweezers.Because of the impact of the epidemic, the progress of many works is surprisingly slow. After many experiments, we have realized its basic functions and prototype.I share our experience here and welcome your comments. We will continue to optimize the design, If more electronic enthusiasts are interested, we will try to cooperate with more friends to make it into a product.Compared with other LCR tweezers, this one uses a new high integrated scheme, which has higher accuracy and more stable test results. At present, it supports 100 / 120 / 1k / 10kHz, 0.5 and 1V excitation signal and impedance measurement, such as ESR,D,Q... The structure design of these LCR tweezers is much more stable, and the user experience is more like precision tweezers.Cap Measurement Noise performance videoThe screen measurement data update rate is 2 samples per second, which is much faster than the other high precision SMD testers, and there are about 100 samples record for 5pF cap measurement, 6fF peak to peak noise performanceFeatures as the attached image, continuous updatingThese are the test results for precision resistors and caps at this moment:The DUTs were Vishay S102 serial 1K 0.01%, 20K 0.01%, 100k 0.1%The DUT is 5pf + 0.5pf @ 10kHz and 10nf 1% @ 1kHz MKP capacitors

author: tautech
author_rank: Super Contributor
timestamp: February 21, 2021, 12:26:59 am
content: Will it have an Auto mode ?When measuring electrolytics ESR should be displayed.What battery technology are you planning on using ?Can you fit a tiny battery level bar meter on the display or will you just pop up a battery low warning ?

author: S. Petrukhin
author_rank: Super Contributor
timestamp: February 21, 2021, 12:46:22 am
content: When and at what price do you plan to sell?

author: Shannon
author_rank: Frequent Contributor
timestamp: February 21, 2021, 02:45:13 am
content: Quote from: tautech on February 21, 2021, 12:26:59 amSure, it will have auto mode, which could distinguish the DUT type and recommend the appropriate frequency automaticallyESR would be implemented with Cap measuring, and Inductor measurement would have the similar Rs function.We are trying to make it a real LCR meter, support those measurement modesWe use a rechargeable Li-on Battery, the battery level would be displayed on the screen.Actually, we are focusing on the display now, I don't think it will be longType-C Port has been used for battery charging as attached.

author: tautech
author_rank: Super Contributor
timestamp: February 21, 2021, 02:47:58 am
content: Quote from: Shannon on February 21, 2021, 02:45:13 amNot in Auto mode ?My old ST3 tweezers can do ESR in Auto mode.

author: Shannon
author_rank: Frequent Contributor
timestamp: February 21, 2021, 02:53:33 am
content: Quote from: S. Petrukhin on February 21, 2021, 12:46:22 amAt present, we think the price will be around $100 for mass productionWe will try to launch it on Kickstarter in one month. If crowdfunding is successful, the delivery time is expected to be two months

author: Shannon
author_rank: Frequent Contributor
timestamp: February 21, 2021, 02:58:51 am
content: Quote from: tautech on February 21, 2021, 02:47:58 amThanks tautech, we will do that.The logic would be Auto mode will switch to Cap or Inductor measuring mode, and the ESR value would be displayed at the same time when cap value is displayed

author: floobydust
author_rank: Super Contributor
timestamp: February 21, 2021, 05:11:16 am
content: How does it perform with MLCC?Because the voltage coefficient of capacitance is quite bad with MLCC, the original Smart Tweezers did not read them correctly and needed firmware update.Example 10uF 10V 0603 at 3V is -40% for only 6uF. If you use a single ramp (compared to AC) to measure capacitance, then the value will be incorrect.

author: Shannon
author_rank: Frequent Contributor
timestamp: February 21, 2021, 05:27:23 am
content: Quote from: floobydust on February 21, 2021, 05:11:16 amI can't agree with you anymore, the excitation signal is a key factor for the performanceWe used a pure AC signal for R/L/C components.10pF cap excitation waveform attached.

author: tautech
author_rank: Super Contributor
timestamp: February 21, 2021, 06:16:16 am
content: Quote from: floobydust on February 21, 2021, 05:11:16 amMy 2007 ST3 reads a 10uF 0805 at 8.54uF ESR~100 mOhm at 10 KHz

author: indman
author_rank: Super Contributor
timestamp: February 21, 2021, 08:01:15 am
content: Del

author: indman
author_rank: Super Contributor
timestamp: February 21, 2021, 08:14:44 am
content: Del

author: Shannon
author_rank: Frequent Contributor
timestamp: February 21, 2021, 09:04:55 am
content: Quote from: indman on February 21, 2021, 08:01:15 amThanks indmanThe ESR, Q and D measurement function have been implemented, UI is under modifying, we will make the main parameter and secondary parameter display at the same time10nF SMD Cap ESR measurement attached.

author: Shannon
author_rank: Frequent Contributor
timestamp: February 21, 2021, 09:32:03 am
content: Quote from: indman on February 21, 2021, 08:14:44 amHi there, you are right, the noise would exceed 0.0001pF, and so many digits for pF level cap is unnecessary, but sometimes the noise could less than 0.01% as the video attached.and the other way to get lower noise is by increasing the sampling time for averaging.the basic accuracy we achieved is 0.1% now, so the last digit would be not displayed in the end.

author: indman
author_rank: Super Contributor
timestamp: February 21, 2021, 10:23:50 am
content: Del

author: S. Petrukhin
author_rank: Super Contributor
timestamp: February 21, 2021, 10:34:27 am
content: Quote from: Shannon on February 21, 2021, 02:53:33 amThis is too expensive to replace the wires of a stationary LCR meter.You've seen that the pretty model DT71 is 2 times cheaper. I'm not talking about the price of simple tweezers UNI-T, Mastech and Holdpeak.

author: Shannon
author_rank: Frequent Contributor
timestamp: February 21, 2021, 11:37:14 am
content: Quote from: S. Petrukhin on February 21, 2021, 10:34:27 amI guess, you've seen that the pretty model ST5S/LCR Pro1 is 2 or 3 times expensive.Well, I don't want to talk much about those product's shortcomings, they are more like DMM, here is a test and analysis post, you can get more details.https://www.eevblog.com/forum/testgear/lcr-tweezers-test-and-analysis/Have you ever seen an LCR Tweezers that could achieve 0.01% noise performance at that speed?And look at the test image, we used 0.01% 2ppm precision resistors for the DUT.We will post more details about the performance and structure design, it used as real precision tweezers, very easy to hold 0402 SMD components.It is much more convenient to use than a stationary LCR meter, it could support SMD(independent or soldered on PCB) and through-hole components at the same time.We have great confidence in it, you'll want to have a try

author: Shannon
author_rank: Frequent Contributor
timestamp: February 21, 2021, 11:48:32 am
content: Quote from: indman on February 21, 2021, 10:23:50 amyep, we will support the different excitation voltage as wellFor the large capacitance measurement, it's a long story, I will try to unfold it at another time.

author: Zlotnik
author_rank: Regular Contributor
timestamp: February 21, 2021, 11:49:35 am
content: Quote from: indman on February 21, 2021, 10:23:50 amThis!Make the excitation voltage selectable, and include also voltages low enough to not turn on pn junctions. This helps with in-circuit component measurements.Price wise, you'll have to be clear on your value proposition.

author: Shannon
author_rank: Frequent Contributor
timestamp: February 21, 2021, 11:53:40 am
content: Quote from: Zlotnik on February 21, 2021, 11:49:35 amThanks Zlotnik,That's the other main point! we will support selectable excitation voltage for the different test cases, especially for the PCBA components and pin cap measurement.

author: Shannon
author_rank: Frequent Contributor
timestamp: February 21, 2021, 12:44:43 pm
content: Here is the detailed features

author: S. Petrukhin
author_rank: Super Contributor
timestamp: February 21, 2021, 05:02:24 pm
content: Quote from: Shannon on February 21, 2021, 11:37:14 amThe DT71 looks much more elegant and comfortable, the ST5S is unsightly. To use these tools as high-precision seems to me unwise. You can easily calibrate a demo sample and lose accuracy in mass production. If you ensure accuracy in mass production, it will be good. But we don't know that yet.I didn't buy a DT71 for $50 and I won't buy yours for $100, it's expensive and more convenient for me to use a stationary device.It is often very inconvenient to look at the tweezer readings when checking on the board due to the forced position of the tweezers. However, I suggest that you, as a friend function that will cure this deficiency: automatic locking readings. It works like this: if the measured value is stored for more than, for example, 2 seconds, issue a beep and record the readings so that you can turn the tweezers and look at the screen. Of course, the time and on/off of this function must be added to the settings.

author: tautech
author_rank: Super Contributor
timestamp: February 21, 2021, 09:19:16 pm
content: ShannonDo allow for display flipping so to cater for both right and left hand users.Don't change the form factor as it's proven to be very functional and robust.It would seem from the # of digits displayed great accuracy can be obtained however for a device of this type it robs valuable display real estate that might be better used to show some other user setting or measurement parameter.Will your tweezers allow for user firmware updates ?

author: Shannon
author_rank: Frequent Contributor
timestamp: February 22, 2021, 01:09:59 am
content: Quote from: S. Petrukhin on February 21, 2021, 05:02:24 pmElegance comes at some cost. I suggest you take a look at the comments on dt71 in this forumThanks for your advice.We have built in Hold function as the feature table show.We are very serious about mass production specification, so the basic accuracy we cannot figure out in this stage, even through the test result is very good, BUT we have confidence in that because we didn't spend much attention on those calibrations to achieve less than 0.1% as the image shows. We will try to follow the strict definition by using 3 Sigma for the worse case.

author: Shannon
author_rank: Frequent Contributor
timestamp: February 22, 2021, 01:14:47 am
content: Quote from: tautech on February 21, 2021, 09:19:16 pmHi tautech,Thanks for your advice.display flipping is a design goal for this LCR tweezers.We will certainly support firmware updates, but the update method has not been decided yet.I will update the feature list later