LCR Tweezers test and analysis (HP-990, DT71, ST5S...) - Page 1
Forum section: electronics / testgear

author: Shannon
author_rank: Frequent Contributor
timestamp: January 31, 2021, 05:21:41 pm
content: Many years ago, I found the smart tweezers st5s was interesting measurement equipment, it's convenient and accurate, and I think it could help me find out the issues on my PCB without tearing down those components.But now, st5s is still expensive to me, and I still wonder if this equipment deserves 300 USD, and then I found LCR Research Pro1 which could support 100kHz, which could have higher resolution when DUT is an inductor, and the cost is about 10% higher. The cost of Lite 1 is much acceptable, but it's not so accurate.So I try to understand how does it work.The First step is buying the cheapest tweezers and do some test.HP-990B is a nice option. More exactly, this one is not LCR tweezers, the official name is small multimeter, that is specially used to measuring SMD(Surface Mounting Device), there are resistors, capacitors, Diode, Zener and LED. When I went through the manual, I think it's a good tool based on the price, many tested cases have been considered, such as relative measurement.Electrical Specification:The dynamic count is 4000, similar to a common used 3 1/2 handy DMM, there are 2 pieces of spare test pin and special test leads: electric rating 500V 10A, it's a fantastic design, add two probes could make it support more situations.Note: It doesn't mean this meter could stand for 500V, please don't use it to measure high voltage. Max Input 36V DC/AC has been marked on the enclosure.This is what it looks like, not bad. And I use my 0.1% calibration board to exam it, PS. the resistors are 0.1%, the other parts are stand components, it's too expensive to get 0.1% capacitor and inductors, and the size of those parts would be huge. Short is used for zero-ohm calibration, and open is used for zero Farad capacitor calibration.Resistance spec is +/-(2.5% + 5 digits), and all of the resistor test results are within the scope of spec, as for capacitance, Relative function is very useful for the low capacitors, and the capacitor accuracy on my calibration board is about 5%, and meter spec is +/-(2.5% + 5 digits) or +/-(3% + 5 digits). But HP-990B cannot support 100uF, and the spec says the max range is 200uF. and the function for the diode(2mA) LED(1mA) and continuity check works well.

author: Shannon
author_rank: Frequent Contributor
timestamp: February 01, 2021, 04:15:37 pm
content: We can find the main IC is COB package on the PCB, when we open the shell.But you can find that this is a good mechanical structure design, with silicone anti-skid material around it to increase comfort, and the arc-shaped shell is also convenient to hold.Some details are not perfect. We found a manual divider, two stacked resistors connected in series with another resistor, and other traces of capacitor modification,The tweezer's arm at the end is directly welded on the PCB, with some traces of flux. I'm very curious about the material of this tweezer's arm. It should be stainless steel with a coating. It has high strength and can be directly welded on PCB. It is obvious that the tweezers do not use the four-wire Kelvin measurement method.Guess that the integrated chip in the middle is a multimeter measurement chip, which integrates the measurement mode of resistance, capacitance, diode, etc. as for the function of LED, it seems that it is very rare on the multimeter, so we need to make a constant current source with 20V compliance voltage to output 1mA current to measure the voltage on the LED.The input terminal can see mz4 series PTC, the resistance value is about 1.5k at room temperature, such a circuit is very common in the multimeter, usually used to protect the input terminal, when the voltage is too high, the PTC will heat up, the resistance value will increase, and the chip will be protected.Under the automatic resistance measurement mode, the current flowing through the resistance to be measured is 0.177ma when it is less than 1kohm. When it is more than 1kohm, the current flowing through the resistance changes with the change of resistance value. When the DUT is 10K, the current is 20uA, and when the DUT is 100k, the current is 2uA. Therefore, at this time, the voltage at both ends of the resistance is 200mV. It looks like it is the same as the multimeter. It takes about 6S to measure the 10ohm resistance by switching the series-connected divider resistance and DC excitation. The value keeps increasing from 0 to 10ohm until it is stable.Under the automatic capacitance measurement mode, I used an oscilloscope to measure the voltage waveforms at both ends of the capacitor. The waveforms in the figure are the waveforms when the DUT is 10nf.It seems that the RC charging circuit is used to calculate the charging and discharging time, and I found one thing. This instrument supports the measurement of 100uF, but the test time is longer. It takes about 25s, my God, There is no movement on the screen until the test results are displayed. The capacitance test circuit is shown in the figure below. An RC OP-AMP oscillation circuit can calculate the capacitance value of capacitance C by measuring the frequency of the output square wave and the known resistance valuethe calculation function isf = 1/(2RC*ln(1 + 2R1/R2))assume R1=R2, then f = 1 / (2RC * ln(3)) and ln(3) = 1.099it's not hard to get the value of CFor the measurement of LED, I found that it can support the series connection of several LEDs, and the minimum excitation voltage can be up to 20V. But I didn't find any inductance. It seems that the charge pump is used to provide a higher voltage, and there are many large capacitors on the PCB.

author: tautech
author_rank: Super Contributor
timestamp: February 02, 2021, 08:38:55 am
content: 100uF = No response ?Really ?Of uF values it can resolve, will it display ESR ?All the good SMD tweezers can which negates the need to get a dedicated ESR tester.

author: Electro Fan
author_rank: Super Contributor
timestamp: February 02, 2021, 08:39:38 am
content: Nice post.Did you make the calibration board or is that a commercial product?

author: indman
author_rank: Super Contributor
timestamp: February 02, 2021, 09:11:01 am
content: Quote from: Shannon on January 31, 2021, 05:21:41 pmThis is not a very good tweezers model! More successful in terms of functionality was the HP-4070C model with an installed DTM0660L processor.This processor allows you to measure capacitance values ​​up to 100mF (100000microF)

author: Shannon
author_rank: Frequent Contributor
timestamp: February 02, 2021, 02:14:53 pm
content: Quote from: tautech on February 02, 2021, 08:38:55 amIn fact, 100uF can be measured, but the time is a little longer, which makes me think that there is no response. The actual measurement time of 100uF is 25 secondsthe capacitor measurement method is the same as a handy DMM, and there is no gear switchingyep, you are right, good SMD tweezers can measure ESR and many other parameters, this one is not so good, the price of this one on amazon is about $26

author: Shannon
author_rank: Frequent Contributor
timestamp: February 02, 2021, 02:27:49 pm
content: Quote from: Electro Fan on February 02, 2021, 08:39:38 amyep, I design the calibration board, and one Chinese friend helped with manufacturing,0.1% 25ppm resistors, from 10ohm to 1Mohmand the capacitor is not so accurate, I planned to use 1% capacitors, but then we found the capacitors are too expensive for few pieces, so we used 5% accuracy in this version

author: Shannon
author_rank: Frequent Contributor
timestamp: February 02, 2021, 02:47:11 pm
content: Quote from: indman on February 02, 2021, 09:11:01 amYou are right, HP-4070C is better than HP-990B, even though they all used DMM IC to measure resistor and capacitors.By the way, how much did you speed for HP-4070C, It doesn't seem to have that much stock

author: indman
author_rank: Super Contributor
timestamp: February 02, 2021, 03:15:28 pm
content: Quote from: Shannon on February 02, 2021, 02:47:11 pmI do not understand what speed do you want to know? Please clarify.

author: Electro Fan
author_rank: Super Contributor
timestamp: February 02, 2021, 03:29:45 pm
content: Quote from: indman on February 02, 2021, 03:15:28 pmThat might have been meant to be “spend”.

author: Shannon
author_rank: Frequent Contributor
timestamp: February 02, 2021, 03:33:04 pm
content: Quote from: indman on February 02, 2021, 03:15:28 pmFT... it's typing errorBy the way, how much did you spend on HP-4070C, It doesn't seem to have much stock on amazon.

author: Shannon
author_rank: Frequent Contributor
timestamp: February 02, 2021, 03:35:48 pm
content: This is a good LCR tweezer, if you only spend 26 dollars, it can measure the general resistance and capacitance requirements, and it seems to be more friendly to SMT devices.Well, it's time to say the disadvantages1. The structural designer does spend a lot of effort on the appearance and structure, but it's hard to say that this is a beautiful tweezer, and the quality is not very good. There is a dedicated box to hold it, but the box is not so good-looking2. This is a SMT tweezer, but it can only measure the devices that have been soldered on the PCB. Because it is very easy to clip the chip components, even 0805, which gives people a very unstable feeling to operate it carefully, and the tweezer's arm is directly soldered on the PCB. This is a convenient way to fix it, but it is not a high-strength way3. The tip of the tweezers is not so sharp. Every time you measure the device on the PCB, you always worry about not touching it or slipping it off4. In the natural state, the opening distance of the tip of the tweezers is too short, which is estimated to be 7mm, so it is not convenient to measure larger devices5. The measurement speed is too slow. It takes 7 seconds to measure 10ohm resistance and 25 seconds to measure 100uF capacitance. OMG, life is short6. PCB quality is not very good, there are many traces of manual change7. Without the Kelvin test method, holding the tweezers arm in hand will affect the measurement results. The display value is about several picofarads, which is not so important for the accuracy of the tweezers8. The quality of the probe is not good, the spec is 500V 10a, I dare not use it to measure high voltage, I have been shocked, I know the taste

author: Electro Fan
author_rank: Super Contributor
timestamp: February 02, 2021, 04:30:30 pm
content: Lots of HP-4070Cs on eBay (but don’t know about the sellers).Another alternative on Amazon (but I haven’t compared the specs or performance vs the 4070C):https://www.amazon.com/Mastech-MS8910-Resistance-Capacitance-tester/dp/B00F3RQCFW

author: indman
author_rank: Super Contributor
timestamp: February 02, 2021, 04:42:17 pm
content: Quote from: Shannon on February 02, 2021, 03:33:04 pmI spent about $14 on my HP4070C, but that was a few years ago.I will disappoint you a little - if you buy this model now, then 99% of you will receive exactly the same filling as the HP-990 model. HoldPeak has also started using chip caseless. But I know for sure that DM1106(upgrade DTM0660) is now installing UT-116C UNI-T into its model

author: Shannon
author_rank: Frequent Contributor
timestamp: February 05, 2021, 02:46:54 pm
content: Quote from: indman on February 02, 2021, 04:42:17 pmDTM0660 or DM1106 is a widely used Handy DMM IC, so these tweezers belong to the same classes based on the DC measurement method.Actually, when I got HP-990, I'm confused that if LCR tweezers (SMD tester) can't be like tweezers, and can't be like LCR meter as well, why don't we use DMM, I can play DMM two test probe as chopsticksAnd I think UT-116C has a similar problem, the structure can't clamp an SMD component, and can't support inductor measurement as well, in my opinion.So generally speaking, this type LCR tweezer(SMD tester) may be just a toy most of the timeFortunately, it's not an expensive man's toyIt's just my idea, do you have similar confusion?

author: Shannon
author_rank: Frequent Contributor
timestamp: February 08, 2021, 04:17:47 pm
content: A real LCR instrument usually uses AC excitation to measure, because inductance and capacitance are more impedance characteristics than resistance characteristics. In other words, capacitance and inductance not only affect the amplitude of (AC) electrical signal but also affect the phase of the "AC" electrical signal.Therefore, the impedance characteristics of the device to be tested can be determined by measuring the influence of DUT on (AC) amplitude and phase. The capacitance of the capacitor and the inductance of the inductor can be obtained through the impedance theoretical calculation formula of the capacitor and inductor.In theory,The impedance formula of capacitance is Z = 1 / JWC, w = 2pi * FThe impedance formula of inductance is Z = JWL, w = 2pi * FR = V / IZ(f) = V(f) / I(f)If the (AC / DC) voltage on the DUT and the (AC / DC) current flowing through the DUT can be measured, the (impedance/resistance) of the DUT can be calculatedIf you don't have an LCR meter on hand, but you have a signal source and an oscilloscope, you can use the resonance method to measure capacitance or inductance. The accuracy is not so high.Auto balancing bridge is an LCR measurement method that is often used, as shown in attached image.This structure of the measurement method can support to 100kHz, but in order to ensure accuracy, the signal source and voltmeter here will choose high-precision DAC and ADC, and with complex digital processing chip, they are expensive and inconvenient to use.

author: Shannon
author_rank: Frequent Contributor
timestamp: February 11, 2021, 05:53:12 am
content: A month ago, I knew the cheapest "AC measurement" LCR tweezers. The model is dt71, which costs only $70, so I bought one to measure the index and analyze the working principle.But I'm a little disappointed that the dt71 measurement method is not so pure "AC". Let's see.First look at the dt71 spec, and then compare with the test results. After self-calibration, the measurement of 0.1% resistance shows that the indicators are all within 1%, not including offset.Compared with hp-990b, it has no function of relative measurementDT71 is 3 digits LCR measure tweezers, the dynamic count is 999, and display count is not fixed, for example, the display value is 0.0ohm, when short the two probe.the noise and stability issue should be taken into account, a part of that noise and drift MAY be caused by the quality of capacitors, but the main issues come from test equipment.By comparison, resistance spec is within the claimed in the manual, for the capacitor specs is a disaster in my mind, noise count is large than offset spec, a little pitty.Then it is found that a strange thing is that the data manual usually uses "AC" to measure the impedance will claim the frequency of the excitation signal used in the measurement results.When using an oscilloscope to measure the signal of resistance gear, it is found that... The figure below shows the voltage waveform at both ends of the probe when measuring resistance. Then adjust the measurement mode to the capacitance gear and observe the waveform of the excitation signal. The excitation waveform looks like an AC signal, but it doesn't seem to be a pure AC signal. The figure below shows the excitation waveform of the capacitance.The test waveform is very close to the capacitance measurement waveform of hp-990b, but the frequency of DT71 test waveform is much higher, and there are two different test frequencies. In essence, the measurement method of dt71's capacitance and inductance is still the same as that of hp-990b. The difference is that dt71 uses two different amplitude excitation signals, which can cover a wider measurement range of capacitance and inductance.It can be seen from the waveform that the frequency of the excitation signal reaches 1MHz at the fastest time. An LCR meter that can support a 1MHz excitation signal is very expensive.

author: Shannon
author_rank: Frequent Contributor
timestamp: February 13, 2021, 03:33:03 am
content: It's time to summarize dt71Advantages:1. The price is cheap. You can buy commercial LCR tweezers for $70, which can support L, C, R, D, frequency, and voltage2. Rich functions, in addition to the LCR function, can also realize signal generator, multimeter, and other functions3. The structure is relatively novel, a bit like a compass. There are many smart designs in it, such as using a permanent magnet to ensure that the tweezers arm is open, using a bite structure at the front end to make the two tweezers arms align at the end, and so on4. Using the popular touch button, the menu is simple, one-button can complete all operations5. With calibration function, it is convenient to calibrate the accuracy of short circuit and open circuit6. Support left and right-hand operation can automatically switchDisadvantages:1. The measurement of LCR is still based on a principle similar to DMM. Without a pure sine wave, it will lead to a difference in accuracy and stability. The most important thing is that there is no equivalent series impedance of capacitor and equivalent DC impedance of the inductor2. There are many test functions, but there are still many problems to be solved. The THD of the output sine wave is very poor, and the frequency of the output sine wave cannot be adjusted3. The structure is not so stable, the tip of the tweezers is difficult to align, and it is not very convenient to measure the SMD device, even if the SMD device has been welded to the circuit board4. The key misoperation is serious, the screen display misoperation is serious, and the display is often reversed5. You can't use it when charging. It's a stupid way. You have to separate your head from your body...6. Kelvin measurement method is not used, and the accuracy in general, so it can only be used for the most basic use7. The handle is poor, mainly because it is too light, so it is easy to touch the arms of the tweezers togetherThe figure below is the default alignment state of the tip of the tweezers. It's hard to imagine that it can be measured by clamping an SMD device

author: fabriciofx
author_rank: Newbie
timestamp: February 13, 2021, 10:17:43 pm
content: Hi!Where did you buy this callibration board?At.te.

author: Shannon
author_rank: Frequent Contributor
timestamp: February 14, 2021, 06:36:25 am
content: Hi fabriciofx,I designed this Calibration board by myself and manufacturing it by my Chinese Friends.Those resistors are 0.1% 25ppm, caps are 5% (1% caps are expensive for few parts).it's quite convenient.If possible, I will manufacture some of them for those who are interested.

author: Shannon
author_rank: Frequent Contributor
timestamp: February 15, 2021, 03:47:58 am
content: Smart tweezers st5s is a well-known commercial precision measuring tweezers. I believe it is a real pure AC inspired LCR meter, rather than the two products mentioned above. It's time to take a look at st5s, which is generally recognized as the best tweezers.As I said, ST5S is a very high precision, and it's very convenient to use, so the price is beyond my plan. The price on Amazon is $311, and the shipping cost is $46. OMG. I thought it was very expensive many years ago, but it's still very expensive for me nowFinally, through the second-hand platform, I bought a second-hand st5s for $120. I thought it was quite worthwhile. Although it was not very good, the button cap was missing, and the tweezers arm was bent. It seemed that its owner didn't care about it. He tried to bend the tweezer's arm to make the tweezer's point aligned.When I got this tweezer, I really liked its performance. It was very powerful and accurate. When I found that it supported ESR and |Z| measurement, I could confirm that this LCR meter really used pure AC signal for measurement, because if the test methods in hp-990 and dt71 were used, it was impossible to measure the ESR characteristics of capacitance, which was great, makes me know the quality of the capacitors.The test frequency supports four frequency points: 100Hz, 120Hz, 1kHz, 10kHz, and supports the automatic identification of components. Dt71 also supports the identification of component types, but st5s can automatically adjust the frequency of the excitation signal to measure the device under test.The main parameter display is standard 4 bits, so the display range is from 0000 to 9999, and the highest resolution is close to 0.01%. The subparameter index is also 4 bits, but there is no clear description of the performance of the subparameter. If the main parameter is very accurate, the accuracy of the subparameter is usually very high.The chapter "how it works", clearly states that st5s uses Kelvin 4-wire measurement method to measure, and finally sees the necessary conditions to realize precision measurement.It is worth emphasizing that st5s supports two kinds of excitation amplitude, which is very good because when measuring SMD components on PCBA, these components are usually connected with the pins of semiconductor devices. If the excitation amplitude is too large, the measured impedance is the result of connecting the diodes inside the semiconductor devices in parallel, so the excitation signal with low voltage amplitude is very useful, which does not exceed that of semiconductor devices At the same time, the parameters of the device can be measured. St5s supports excitation signals of 0.5vrms and 1Vrms, and the accuracy of excitation voltage is 2%.

author: Shannon
author_rank: Frequent Contributor
timestamp: February 15, 2021, 06:35:27 am
content: The resistance index is very good. There is a note below the index, which indicates that the range of 1 ~ 100ohm is minus the offset impedance. The best index is 0.2% + 3counts, and the accuracy under different frequencies is clearly marked, except for 120Hz, because the index of 120Hz is very close to 100Hz.Compared with the test results and indexes, the resistance indexes are all within 0.2% + 3 of the best indexes, which is unbelievable. When testing the capacitance, in addition to the capacitance value, the equivalent RP or equivalent RS parameters of the capacitance can be obtained through the sub-parameters, and the quality of the capacitance can be detected. In addition, through st5s, it is found that the ceramic capacitance will change in the measurement process, which should be due to the piezoelectric effect of the ceramic capacitance, resulting in a small change in the capacitance value. St5s can detect this slow change phenomenon.The figure below is the waveform of the excitation signal. The device to be tested is the probe of the oscilloscope. The input capacitance is about 10PF. The default test frequency is 10kHz. The waveform is a very beautiful AC 10kHz 0.5Vrms sine signal.The internal circuit looks very complicated, salute to the designers.

author: Shannon
author_rank: Frequent Contributor
timestamp: February 15, 2021, 06:47:55 am
content: ST5S summary:This is the best commercial LCR tweezers I have ever usedAdvantages:1. Very, very accurate2. The function is very powerful, which can be compared with the standard LCR meter3. Support Kelvin measurement4. Compact designDisadvantages:1. A little expensive2. The structure design is the best LCR tweezers I have ever used, but there is still a gap between real tweezers3. Although it is very accurate, it does not support self-calibration, which may be a disadvantage

author: tautech
author_rank: Super Contributor
timestamp: February 15, 2021, 07:13:13 am
content: For 15 years I have used the earlier ST3 and even back then the cost was a disincentive to purchase although with a quality tool the initial cost hurt is now long forgotten. They are mygotocomponent tester as with that cost also provides you an ESR tester ....another piece of equipment you don't need to buy.Some think tweezers are only suitable for SMD and to that I say BS as the tweezer legs can be spread to cover most through hole devices.Would I buy another ? In an instant !

author: indman
author_rank: Super Contributor
timestamp: February 15, 2021, 07:23:59 am
content: Quote from: Shannon on February 15, 2021, 06:47:55 amAnother disadvantages is that it does not have a test frequency of 100 kHz.Tweezers of similar cost have such an option.

author: 2N3055
author_rank: Super Contributor
timestamp: February 15, 2021, 08:19:52 am
content: I have LCR Pro1. It has self cal, diode mode that can light up LEDs, DC resistance mode...Goes to 100kHz, has setable voltage levels from 0,2 to 1 V and is a proper impedance analyser.Works well, and is quite accurate, form what I could verify..As Tautech says, if I need to measure LCR, (SMD or not) it is first thing that I grab... It's just so convenient and easy...If it breaks, I would get another one quickly.

author: indman
author_rank: Super Contributor
timestamp: February 15, 2021, 08:40:27 am
content: 2N3055,can you make a video of how your tweezers work when measuring low impedances?I am interested in the stability of the readings of this device. 2-wire measuring circuit for tweezers! Stability 4 digits after the decimal point is a random number generator!

author: bateau020
author_rank: Frequent Contributor
timestamp: February 15, 2021, 10:09:48 am
content: As I have the same tweezers (LCR pro1 plus), I can chime in. These tweezers are really stable when the device under test is not ambiguous. Sometimes you have to force it to C or L tests, but in general, the tool is very reliable, versatile and fast. I prefer it over my DE-5000 clone.Attached is a video of the tweezers on a 1 ohm resistor. (in a zip, don't know how to quickly add a video outside of pushing it to youtube or the like)As you can see, some noise, but not too bothersome.

author: indman
author_rank: Super Contributor
timestamp: February 15, 2021, 10:20:45 am
content: bateau020,there is no noise on your video, but a random number generator in the last 2 bits.Can you measure the resistance with 10-20 milliohms with your tweezers?

author: 2N3055
author_rank: Super Contributor
timestamp: February 15, 2021, 11:46:51 am
content: Quote from: indman on February 15, 2021, 10:20:45 amNoise IS the random number generator, the original one...You can measure miliohms, but it won't be as stable as dedicated miliohm meter and kelvin clips.You will never have stable milliohms on a tweezer with contact surface of fraction of millimetre square, and hand regulated pressure.You need clips with bigger contact surface area and spring to achieve semi stable and repeatable pressure.

author: indman
author_rank: Super Contributor
timestamp: February 15, 2021, 12:05:51 pm
content: Quote from: 2N3055 on February 15, 2021, 11:46:51 amDo you have such devices that you listed? Did the manufacturer of this tweezers put these extra contacts in the kit with the device? Otherwise, what are these 2 additional unstable digits? Indicator? Marketing?

author: 2N3055
author_rank: Super Contributor
timestamp: February 15, 2021, 12:59:26 pm
content: Quote from: indman on February 15, 2021, 12:05:51 pmI will try to explain this gently, because I know sometimes it is hard to express yourself in foreign language.Your tone fells sarcastic and not very nice and I am not certain what do you want with all these questions.I don't know if that is intentional or you just struggle to find proper words in foreign language.I didn't make those tweezers and have no idea why manufacturers implemented so many decimals when they are not even necessary.In datasheet they specify all technical specifications, and device certainly perform better than specified..I personally would like if they would have less digits because it is not useful or accurate to displayed number..But I got used to it, know how to read what I want and I don't care. It doesn't make it less good or useful, although I agree with you that it is silly.As I said I didn't make those tweezers and have no connection to manufacturer whatsoever. I speak from my own experience and I paid for it with my own money.If I had a chance to buy better tweezers for half the money, I would buy it gladly....If you know the better, cheaper, ones, please share with us... I'm interested.Regards,

author: bateau020
author_rank: Frequent Contributor
timestamp: February 15, 2021, 01:45:10 pm
content: In theory it is possible to equip these tweezers (and the LCR Reader, the ST5S, and probably others) with 4W kelvin probes. See the attached image.But you cannot simply buy them. The makers of the "LCR-Reader" have an extension cable that extends one end of the tweezers, via a kelvin cable (LCR-PC). But it ends in a simple probe again. Therefore: same problem.There is a big reason you will not see milliohm measurements for this type of instrument: it requires larger currents if you want more precision. So even if possible, you would eat batteries like crazy.Just use a dedicated instrument. Even my DE-5000 clone with 4W kelvin clips is not what I use for milliohm measurements. I just pump large currents through it and measure it the hard way, with 2 multimeters. But you could also get a good bench MM.

author: indman
author_rank: Super Contributor
timestamp: February 15, 2021, 02:03:37 pm
content: Quote from: 2N3055 on February 15, 2021, 12:59:26 pmI also agree with you and did not want to offend you as the owner of this device. But I am critical of when a manufacturer (seller) for marketing purposesdoes stupid things that customers don't need.I know of a few really serious tweezers that are worth the cost, like the HB-14 or the newer HB-15.But I don't know if these tweezers are sold in your countries, since the author and manufacturer of these devices is from Russia.

author: bateau020
author_rank: Frequent Contributor
timestamp: February 15, 2021, 03:10:24 pm
content: Quote from: indman on February 15, 2021, 02:03:37 pmNever heard of them before. The only link I found is this:https://www.electronicspoint.com/forums/threads/smart-lcr-tweezers-lcr-pro1-russian-rlc-tweezers-hb-14.291164/page-4.But unfortunately that thread has some very contrasting information in it, and does not look very balanced. Will read up on them some more.Added:They are also known as NV-14 it seems.And have been mentioned here before:https://www.eevblog.com/forum/testgear/tweezers-for-low-impedance-capacitors/Manufacturer website:http://rlc-esr.ru/index.php/en-us/multimetr-pintset-nv15But the manual only seems to exist in russian.

author: indman
author_rank: Super Contributor
timestamp: February 15, 2021, 03:29:20 pm
content: bateau020, read all 5 pages of this topic. Don't pay too much attention to the messages fromcapsis a troll known by various names. He is trying to measure a very clean ESR to 6 decimal places on a dial gauge marked with a thick felt-tip pen.

author: Shannon
author_rank: Frequent Contributor
timestamp: February 15, 2021, 03:37:29 pm
content: I try to explain why do these tweezers cannot support milliohm resistance.Because they said they cannot support in the datasheet.ST5S has an offset spec, For the resistance ≤ 25mΩLCR Pro1 has a similar spec, looks like the offset is ≤ 20mΩ

author: 2N3055
author_rank: Super Contributor
timestamp: February 15, 2021, 06:56:14 pm
content: Quote from: indman on February 15, 2021, 02:03:37 pmNo worry, no offence taken, I just like to be direct and also meant no offence.I agree that many manufacturers choose marketing over truth, and hate it as much as you..I know about HB14 and HB15 and would have bought them, but it's not simple importing from Russia ... They seem like good instruments.If only we could organise sales here in EU, I believe they would sell well.Best regards

author: Electro Fan
author_rank: Super Contributor
timestamp: February 15, 2021, 07:00:03 pm
content: Maybe there is an opportunity for an EEV branded tweezer.

author: 2N3055
author_rank: Super Contributor
timestamp: February 15, 2021, 07:03:51 pm
content: Quote from: Shannon on February 15, 2021, 03:37:29 pmWith LCR Pro1 you can calibrate it out, to few miliohms...Problem is, as I said, that tiny pointed tweezer tips cannot have low enough contact resistance to have repeatable measurements...As you vary pressure, resistance changes in front of your eyes.. It can measure it just fine.For larger trough hole components, if you make contact with wider flat part of tweezers, you get better results.Also you need to clean tips with alcohol occasionally, it's gold plated and it wont corrode but it will get dirty..

author: tautech
author_rank: Super Contributor
timestamp: February 15, 2021, 07:36:35 pm
content: Quote from: Electro Fan on February 15, 2021, 07:00:03 pmOnly if Dave has changed his ideas about SMD tweezers.When he reviewed the ST3 years back he didn't think much of them yet many of us have been using them for years.

author: Shannon
author_rank: Frequent Contributor
timestamp: February 16, 2021, 03:44:01 am
content: Quote from: tautech on February 15, 2021, 07:36:35 pmhahaI watched Dave's ST3 video again, and he was so funny "I love Canadians!"In fact, My friends and I have discussed this topic, and we think that a more cost-effective tweezer with similar performance may be possible now

author: Shannon
author_rank: Frequent Contributor
timestamp: February 16, 2021, 04:01:23 am
content: Quote from: 2N3055 on February 15, 2021, 07:03:51 pmYes, I agree with you. I've also thought about this issue.Is it possible to make tweezers tip into a pen tip like structure? Each tweezer tip is composed of two metal tips. It's cool to think of.as attached.Another problem is that for the LCR meter, the measurement of milliohm level is limited by the amplitude of the excitation signal, it is not easy to measure, asbateau020saidSuppose the exciting current is 1mA, the resistance is 1mOhm, and the voltage amplitude is only 1uv

author: Electro Fan
author_rank: Super Contributor
timestamp: February 16, 2021, 07:56:51 am
content: Nice illustration Shannon 👍

author: bateau020
author_rank: Frequent Contributor
timestamp: February 16, 2021, 10:48:49 am
content: Nice quote from another thread running now:Quote from: bdunham7 on February 15, 2021, 06:13:08 pmNow that voltage (from the Seebeck effect if I remember correctly) is DC or close to DC, so measuring in AC would allow mitigation. However, its noise adds to the noise in your input stages. Add that to the varying quality of the contact (which is the main problem I think), and the proximity of a heat source (hand), and you got a situation that is not favourable.

author: Shannon
author_rank: Frequent Contributor
timestamp: February 16, 2021, 03:14:02 pm
content: Quote from: bateau020 on February 16, 2021, 10:48:49 amYep, You reminded me, it is possible to obtain higher signal-to-noise ratio base on using AC excitation signal to measure impedance,Some high-precision Wheatstone bridges use AC excitation to avoid low-frequency noise.But if power consumption and temperature rising of large current are acceptable, DC large current is a more easy choice.

author: bateau020
author_rank: Frequent Contributor
timestamp: February 16, 2021, 03:59:58 pm
content: Quote from: Shannon on February 16, 2021, 03:14:02 pmDepends on the use case.If you want to find a short on circuit board, you will need to do it in DC or a low frequency. Otherwise you will measure the caps, plus the board layout will add inductance, so you will be mislead. Just keep the voltage low enough to no to fry components. Well, you could go fancy and test through pulsed excitation, but then you are in the area of the higher end tools.If you have 1 component that you want to test, then AC could be better.By the way, for testing on boards in the milli-ohm range it is best to avoid tweezers: contact surface and pressure have too much influence on the measurement, and are relatively hard to control with tweezers. Use pointy kelvin probes, and they are hard to find (the battery test kelvin probes are easy to find, but they are way too large). For those who want to see how it's done, look what Robrenz did. Deep respect for his skills.

author: serg-el
author_rank: Regular Contributor
timestamp: February 16, 2021, 08:05:41 pm
content: I already wrote earlier in another topic, and attached photographs.Kelvin probes with a short distance are easy enough to make from felt-tip pens and sewing needles.Shielded wires. Closed relay contacts and tracks between contacts are clearly distinguished on the boards.Relay resistance is higher;)And my tweezers are HB-1. The first of the HB series. We have already written about them above in the topic. (NV-14, NV-15).

author: fabriciofx
author_rank: Newbie
timestamp: February 16, 2021, 09:55:14 pm
content: Shannon,Please, can youy let me know when you start sell it?Best Regards.

author: Shannon
author_rank: Frequent Contributor
timestamp: February 17, 2021, 02:23:56 am
content: Quote from: bateau020 on February 16, 2021, 03:59:58 pmShocked me, Deep Respect!

author: Shannon
author_rank: Frequent Contributor
timestamp: February 17, 2021, 02:33:16 am
content: Quote from: serg-el on February 16, 2021, 08:05:41 pmYour design is very creativeDo you use the sewing needle to make the probe?What a smart choice!

author: Shannon
author_rank: Frequent Contributor
timestamp: February 17, 2021, 02:58:13 am
content: Quote from: fabriciofx on February 16, 2021, 09:55:14 pmHi fabriciofx,We have conducted many experiments, but we still attempt to get more ideas and help to make it better or make it true.We are experienced in how to design a product, but we have few ideas on how to sellSome guys recommend Kickstarter to me, is Kickstarter convenient for you?Regards

author: tautech
author_rank: Super Contributor
timestamp: February 17, 2021, 03:06:39 am
content: Be aware you will need to compete with the Mastech MS8911 if you are to enter the low cost SMD tweezer market.

author: Shannon
author_rank: Frequent Contributor
timestamp: February 17, 2021, 03:37:20 am
content: Quote from: tautech on February 17, 2021, 03:06:39 amHi tautech,Really appreciate your remindingIf we try to make it true, our goal is that the performance is no worse than st5s, and the test results give us confidence at present

author: indman
author_rank: Super Contributor
timestamp: February 17, 2021, 11:15:36 am
content: Quote from: indman on February 15, 2021, 02:03:37 pmSimilar tweezers are sold here under the names LCR-Reader-MP and LCR-Reader-MPAhttps://secure.lcr-reader.com/catalog/product_info.php/products_id/94https://secure.lcr-reader.com/catalog/product_info.php/products_id/87

author: bateau020
author_rank: Frequent Contributor
timestamp: February 17, 2021, 11:38:52 am
content: Quote from: indman on February 17, 2021, 11:15:36 amIt may be a bit confusing, but the LCR-Reader series and the ST-5S series come from the same place. Seehttps://lcr-reader.com/LCR-Reader* = consumer model. ST* = pro model.

author: indman
author_rank: Super Contributor
timestamp: February 17, 2021, 12:09:48 pm
content: Available model LCR-Reader-MPA Pro

author: serg-el
author_rank: Regular Contributor
timestamp: February 17, 2021, 07:53:13 pm
content: Siborg Systems Inc. the thieves. The design of the LCR-Reader-MP body was developed by the author back in 2011.And everything else was stolen too.https://www.lcr-reader.com/lcrreadermp.htmlhttp://rlc-esr.ru/forum/index.php?topic=14.0Video from the author from 2013.https://youtu.be/iulsbC9Gj-0

author: Shannon
author_rank: Frequent Contributor
timestamp: February 18, 2021, 06:28:04 am
content: Quote from: serg-el on February 17, 2021, 07:53:13 pmIt subvert my understanding.So LCR-Reader-MPA and LCR-Reader-MP has the same circuit with HB14?and smart tweezers series, such as ST5S/Colibri, are similar with HB1 as well?

author: tautech
author_rank: Super Contributor
timestamp: February 19, 2021, 07:09:41 am
content: The SMD tweezers marketplace is full of confusion with one brand copying the IP of another.AFAIK these are the originals of which I still have their now 10+ year old ST3:https://www.smarttweezers.com/A quick test for another thread.10uf 0805 in the plastic tape and 330uf between the screws of the tweezers

author: WaveletSea
author_rank: Newbie
timestamp: September 25, 2021, 03:45:32 am
content: http://www.rlc-esr.ru/index.php/ru/multimetr-pintset-nv15http://www.rlc-esr.ru/index.php/ru/kupit/%D0%BF%D0%B8%D0%BD%D1%86%D0%B5%D1%82-%D0%BD%D0%B215-1-2028-detailThis one looks very cool.Did someone has already one ?

author: ceut
author_rank: Regular Contributor
timestamp: December 21, 2023, 07:39:55 pm
content: Hello,I'm looking for SMD Tweezers, and I find this topicSo I have checked this new Russian one for buying it:http://www.rlc-esr.ru/index.php/ru/pintset-nv17It seems to be a great tool !Avalaible in January.But it seems that it is only sold locally in Russia.Also, I have looked at the LCR-MPA canadian tweezer, and it seems the canadian are copying like this:HB-15 => LCR-Reader-MPAHB-16 => LCR-Reader-R2HB-17 => maybe LCR-Reader- ? ? ?HB-17 new feature (taken from HB-16 // HB-17 seems to be a mix of HB-15 and HB-16):But the canadian sells all at astronomical priceAnd no link for product fimware update, only User Manual.Whereas the Russian model has update.Will the HB-17 also be copied by the canadian when it will be out ?Also, is there a way to buy the Russian model somewhere ?Thanks

author: tautech
author_rank: Super Contributor
timestamp: December 22, 2023, 10:44:12 am
content: ceut, member Shannon has his SMD tweezers available from his shop on Aliexpress and here’s his thread of the development progress where many have contributed to the end design.As a happy customer I have zero reservations in recommending the ST42 SMD tweezers from Shannon.https://www.eevblog.com/forum/testgear/design-a-new-precision-lcr-tweezers/

author: ceut
author_rank: Regular Contributor
timestamp: December 22, 2023, 04:30:50 pm
content: Quote from: tautech on December 22, 2023, 10:44:12 amHello Tautech,As always, you are really good for advicesI'm checking for this tweezers on Youtube reviews and on the link you gave me + his website: it seems to cover all my needs so I go to buy oneAnd it comes from an eevblog user so it is a big argue for meThank you! And happy end of year holidays