Smart Tweezers - Page 1
Forum section: electronics / projects

author: bostonman
author_rank: Super Contributor
timestamp: November 22, 2022, 04:34:21 am
content: At an old job we had a set of "smart tweezers", similar to this:https://lcr-reader.com/digikey/LCR-Reader_Flier_web.pdfHaving recently worked on stuff that had chip resistors, caps, and inductors, that were too small to have a value on them (although I don't remember seeing inductors with a value on them), I began wondering if smart tweezers is a good investment.First off, I never understood how they worked. If two components are in parallel, say maybe even just two resistors with both a value of X, how do the tweezers not read their parallel (half) resistance?In any case, does anyone have input on how good these are for the money and/or suggest a model worth buying?

author: tautech
author_rank: Super Contributor
timestamp: November 22, 2022, 06:31:21 am
content: 100% would recommend them......from the better brands especially.Some 15 years ago I grabbed a set of ST3's and never regretted it, the little brother to the ST5's, one of the premier products available today.https://www.smarttweezers.com/st5s/Member Shannon went on a mission to develop and build cheaper smart tweezers and seems to be doing not bad but had a problem with tip design having them like needles to penetrate conformal coatings whereas he would have been better to make them more robust. He hasn't updated us on product development so it might be a good idea to give him a poke as his pricing was pretty good.https://www.eevblog.com/forum/testgear/design-a-new-precision-lcr-tweezers/Shop:https://www.aliexpress.com/item/1005004239869204.html

author: Siwastaja
author_rank: Super Contributor
timestamp: November 22, 2022, 09:16:42 am
content: Had access to SMD measurement tweezers, not as fancy (no ESR) but anyway, for many years, never used them. I never find myself measuring a "value" of component, especially SMD. SMD parts are easily damaged by desoldering, and are $0.001 each so you just pick a fresh one and solder it in, so you know the "value" (and more, to be exact: all specifications).If it's my own design, then I know what part I need, or what part I want to use. The only reason to measure values would be repairing or reverse-engineering a design, so if you do that, then your situation might be different from mine. I do teardowns for analysis, but rarely to the level of measuring values of resistors or capacitors.

author: bostonman
author_rank: Super Contributor
timestamp: November 22, 2022, 01:15:57 pm
content: QuoteThis wouldn't be for desoldering and measuring, this would be to get the value of a component before i unsolder it. As an example, I had four parallel circuits (I was repairing a scope with two bad channels that were worked on by someone else) and needed resistor values in the good channels so I could confirm whether the previous person used the correct values. If I unsoldered them, I run the risk of damaging them, so getting the value ahead of time would be good.QuoteAre there certain models with better range for caps and stuff? I may be wrong, but think a good range would be 1pF and up to 100uF, resistance from 10ohms up to a few meg, and I'm uncertain about inductance ranges as it's rare I ever question an inductor.As for the accuracy when the component is in a circuit, how can they be accurate? If a circuit has two parallel resistors or an inductor in parallel with a cap, then it seems the circuit would trick the tweezers into thinking it's seeing some other value.

author: tautech
author_rank: Super Contributor
timestamp: November 22, 2022, 07:54:38 pm
content: For measurements in circuit, unless you have a schematic so to see multiple measurements paths no instrument can provide reliable in-circuit measurements. Get used to this reality.Develop skills to quickly remove components for testing and learn how to judge when a in-circuit wrong measurement doesn't matter. eg, a resistor reads lower than labelled then there is another conductive path. Measures higher, Houston we have a problem.You learn most of this with a snail slow DMM but a set of tweezers sure speeds things up and just because they are primarily used for SMD don't mean you can't use them for TH too or for that matter anything you can stretch the tweezer legs over.TBH I think Shannon has done a good job with his set and if I had my time again I'd go with a set of his.You can fret about measurements way down in the pF but it costs money to properly do that when instead you can buy parts with a specified value and tolerance and know they will be close to actual value.

author: bostonman
author_rank: Super Contributor
timestamp: November 22, 2022, 08:41:01 pm
content: QuoteThis was my opinion. I haven't researched them recently, but know the ones at my old job advertised in circuit measuring and I (along with co-workers) didn't believe it. We never had a reason to put them to test and them in various circuits, but we used them for basic stuff without putting much faith in the reading.I can look at specs, but my guess is the smart tweezers have a better range than a typical Fluke.So is it safe to say they are a good investment, but not an alternative to a Fluke (ignoring whether my previous sentence about range is accurate).

author: tautech
author_rank: Super Contributor
timestamp: November 22, 2022, 08:57:57 pm
content: They are NOT a replacement for a trusted and quality DMM but for component measurements more versatile.For repair work quick capacitor ESR measurements are invaluable and if tweezers have an Auto mode you get that in the same window as the capacitance measurement.Like a DMM you won't always get an accurate diode measurement but you don't need flip leads with tweezers as they measure from both directions.A little experience using tweezers even on scrap PCB's goes a long way to showing what you can do with them.I will never be without a set while I still suck air and can hold a soldering iron.

author: bostonman
author_rank: Super Contributor
timestamp: November 23, 2022, 04:32:20 am
content: I don't have an ESR meter, but have read (on here) various threads about the advantages of checking ESR.Not to deviate, but I feel the ESR in caps is bound to increase over time and many pieces of electronics have caps with ESR much higher and don't show any signs of failure.As for smart tweezers, are they more useful because of size, pointed tips, and not having polarity? Or are they useful because they have features you can't find in other meters?If a component needs to be removed to measure correctly regardless if they advertise not needing to do this, a resistor is cut and dry. Any meter should read just about all resistor values (unless they are milli ohm values in which case you need a milli ohm meter). Inductors are a bit more tricky, but feel inductors will just burn open. The tricky ones I think are capacitors because they can be very tiny (a few pF) to very large.I'm uncertain if I own a meter that can read a 1pF capacitor. Most of my repairs involving caps have been blown capacitors, but, as mentioned, I did come across the need to measure chip caps just to confirm their value (or need to confirm in a parallel circuit because a previous owner messed with it).I'm just wondering if my money is better spent on smart tweezers, or, if I don't own a meter that can measure down to a pF, purchase one.

author: tautech
author_rank: Super Contributor
timestamp: November 23, 2022, 05:18:37 am
content: If you consider where you might find a cap of just a few pF which is normally an oscillator for a clock where we don't measure the caps but instead check the clock is on frequency which if it is we look no further but elsewhere to another circuit building block.Being able to measure and assess ESR is critical to repair work as you have have observed there is often zero indication a cap is bad.Only you can know what features will be required for future work as some for sure will be each of TH and SMD so to do it with ease you need tools for each.I'm a smart tweezer convert for more than a decade and back then I hummed and harred about how much to spend and then went for the then premium product, a set of ST3's.Today I would get Shannon's and maybe his test PCB so to provide more confidence in what is still a recently developed product.

author: bostonman
author_rank: Super Contributor
timestamp: November 23, 2022, 04:44:16 pm
content: QuoteYou're correct. So far I've been able to measure most stuff with my Fluke 179, but, looking at the specs, it has a resolution of 1nF whereas the Shannon Tweezers go down to 0.5pF.Being able to grab onto a 0402 would be nice too. These Shannon Tweezers aren't overly expensive either, so I think it's a great suggestion.The rechargeable battery may be an issue due to eventually leaking. Is it able to be removed when not in use and/or be replaced when it (eventually) goes bad?

author: tautech
author_rank: Super Contributor
timestamp: November 23, 2022, 07:53:55 pm
content: Quote from: bostonman on November 23, 2022, 04:44:16 pmAsk Shannon, I linked the thread earlier and he visits EEVblog every few days.Ask about battery failures to date and how he might manage any future failures.

author: thm_w
author_rank: Super Contributor
timestamp: November 23, 2022, 10:24:45 pm
content: Quote from: bostonman on November 23, 2022, 04:44:16 pmYou can't remove it when not in use, but the device lasts weeks on a charge.The cell can be replaced, I don't know the size off hand.Wearing out of the tips might be a concern.You can read the threadhttps://www.eevblog.com/forum/testgear/design-a-new-precision-lcr-tweezers/msg4243438/#msg4243438

author: tautech
author_rank: Super Contributor
timestamp: November 23, 2022, 10:31:34 pm
content: Quote from: thm_w on November 23, 2022, 10:24:45 pmYes we never did hear back from Shannon if he made the tips more robust but it seems he had 2 designs, maybe he just dropped the finer tips.