Review: SMD Tweezer Meter or Tweezer Probes For Your Multimeter?

It’s remarkable how tiny electronics have become. Heaven knows what an old-timer whose experience started with tubes must think, to go from solder tags to SMD in a lifetime is some journey. Even  the generation that started with discrete transistors has lived through an incredible shift. But it’s true, SMD components are tiny, and that presents a challenge aside from the one you’ll face when soldering them. Identifying and measuring the value of a chip component too small to have any writing upon it becomes almost impossible with a pair of standard test probes.

Happily the test equipment manufacturers have risen to the challenge, and produced all sorts of meters designed for SMD work that have a pair of tweezers instead of test prods. When I was looking for one I did my usual thing when it comes to Hackaday reviews. I looked at the budget end of the market, and bought an inexpensive Chinese model for about £16($21). And since I was browsing tweezers I couldn’t resist adding another purchase to my order. I found a pair of tweezer test probes for my multimeter which cost me just over a pound ($1.30) and would provide a useful comparison. For working with SMD components in situ, do you even need the special meter?

A Packet Full Of Tweezers Arrives

Clipping these tweezers onto SMD devices is easy enough.
Clipping these tweezers onto SMD devices is easy enough.

So in due course my package from Shenzhen arrived, what had I bought? The tweezer test prods were of anonymous origin, but the meter came in a blister pack with a manufacturer’s name and model number. This was it seemed a Chinese-language package, but a bit of Google Translate work revealed it to be a Shenzhen Binjiang BM8910 (translated). Opening the package revealed a CR2032 battery for it, plus a Chinese warranty card and a folded set of English instructions. Installing the battery produced an instant power-on, with the meter entering a scanning mode trying to identify what was across its terminals.

You can tell a lot about the quality of an imported product like this one by the quality of its instructions. Those for the BM8910 are a pleasant surprise, with mostly decent English and well-presented diagrams. The unit itself is about the size of a chunky marker pen, yellow plastic with an LCD display, a couple of buttons, and the Chinese for “Chip resistor/diode/capacitor intelligent tester” according to Google Translate on top. It parts in the middle, and one end slides off to reveal the tweezers themselves, which are insulated spring steel with pointed probes attached to their ends. The instruction leaflet claims that these are gold-plated, I have to say it doesn’t look very golden to me. Aside from this, the overall quality and feel of its construction is good, this may not have cost much but it does not feel too cheap.

Turning it on by pressing the “func” button, and it enters an automatic mode in which it tries to identify the component in the tweezer as a resistor, capacitor, or diode, and give a reading. Pressing “func” repeatedly steps it through individual autoranging resistance, continuity, diode tester, and capacitance modes, and holding the button down turns it off. The other button is a “hold” button, convenient for retaining a reading.

So having investigated the BM8910, I set to with a variety of SMD boards and modules  around my bench. Gripping a part was easy enough, though 0201s require a little care as you might expect. and in most cases the instrument correctly identified their function and value. It becomes a quick way of determining manufacturing quality, for you soon see what tolerance components have been used by the variance in their values. It is worth noting that the continuity function does not have the buzzer you might expect.

As a general point, most component measurements seemed unaffected by their placement in-circuit. An LED series resistor on an Arduino, for example read exactly as it should have. But in cases where RC networks affect the perceived value across a component as you might expect the readings it returns can not be trusted as the value of that component. In general it seems to prefer identifying the resistance of whatever circuit  it sees, and if that includes an inductor it defaults to the DC resistance of that component.

I’d say that if you’re in the market for a not-too-expensive SMD tweezer tester, SZBJ BM8910 is a good option. But this review isn’t over, because I also bought those SMD tweezer test probes for my multimeter. If you’re a really frugal engineer, how do they rack up against a dedicated instrument?

But How About The Basic Option?

You pay not a lot for the tweezer test probes, and to be fair, you get not a lot but what you get isn't bad.
You pay not a lot for the tweezer test probes, and to be fair, you get not a lot. But what you get isn’t bad.

For not a lot of money it’s fair not to expect much in the way of quality. These these £1 wonders are functional tweezers with a plastic grip and a single flex about 50cm (1’6″) long that splits into two wires with 4mm plugs for the meter terminals. The tips of the tweezers aren’t as nice as those on the BM8910, being just the plated spring steel of the tweezers themselves. Operation is simple: plug it into the meter, and you’re good to go.

Gripping SMD devices is easy enough, and identifying resistor values is yet again fairly straightforward. The same issues with networks of components apply, and of course you are limited in what you can measure by what your meter is capable of. Mine doesn’t have a capacitance range, so I was only able to compare the two on resistance and diode testing, on which it compared favourably. It was however extremely useful to be able to measure voltages in-circuit with a device powered on, and I suspect that this is what these probes will end up being used for.

Yet again, these tweezers are easy enough to use.
Yet again, these tweezers are easy enough to use.

The inexpensive SMD tweezer probes are not the highest quality tool you’ll have on your bench, but they are so cheap that it’s an easy choice to add to your arsenal. They aren’t really as convenient as the dedicated instrument for measuring the values of SMD components, but they do bring all the meter’s capabilities to bear and it’s extremely convenient to be able to measure voltages. Buy a set, you’ll find them useful.

This review started as a comparison between two ways of measuring SMD devices on PCBs, and ended with a recommendation to buy both the decent option and the cheap one if you have that requirement.

Regular readers will have followed the occasional series of reviews here of inexpensive imported tools and test equipment, and will know that sometimes the cheapest in the catalogue can be entertainingly bad. In this case it’s a pleasant surprise that the ultra-cheap probes were useful, but perhaps the key to a successful cheap tool lies in extreme simplicity.

22 thoughts on “Review: SMD Tweezer Meter or Tweezer Probes For Your Multimeter?

  1. “Heaven knows what an old-timer whose experience started with tubes must think”

    I’m not sure that heaven knows much of anything but in my experience if you want (or don’t want) to know what those old timers think about something they will be happy to tell you! :-)

    1. Yes, we will be happy to tell you ;~) Started with tubes and not merely 8 pin octal either….I used to laugh at my Dad when he had issues with the small type in the DigiKey catalog. No more…Now I wear reading glasses myself, yuck. I do use a for-real really-good stereo microscope when doing serious SMD work, and when we get to 0402…well, I’d rather not do it myself within a few days of having any caffeine. Or at all, I never really tooled up past a good Metcal solder station, the ‘scope, and some good tweezers. While I have a really good USB microscope…it’s not in the same universe as a true-stereo high quality optic.

      Luckily (or not, depending on your outlook) unless you’re making a real product, most of this stuff is now available already on breakout boards, for what seems like low cost if you once had to spend a good part of a week’s pay on a CK722 transistor. So for home automation and other junk like that, I just use that stuff – at that part of the chain, there’s rarely a signal quality/rf propagation issue with what I do most of the time, so it’s fine for me.

      I’d even call the wide availability of not-too-stupidly priced eval boards another revolution. Those used to be priced so only a big outfit who had engineers sitting around getting paid waiting thought them worth it. Now there’s Adafruit and many others…it’s a new world.

      1. “I’d even call the wide availability of not-too-stupidly priced eval boards another revolution. Those used to be priced so only a big outfit who had engineers sitting around getting paid waiting thought them worth it. Now there’s Adafruit and many others…it’s a new world.”

        Yep! I recall when Motorola released an Eval Kit (dev board) for the 6811, and they charged ONLY $68.11! Unfortunately, I think they made/sold only 68 of them (sarcasm) as I didn’t find out about them until they were gone.
        And the STM dev boards… now I’m a fan boy of them because of their low cost dev boards, and the free seminars that they had to go with those boards!

        1. You should have seen some of TI’s dev kits. $15 DSP cpu, but board, $500, plus more than DevStudio for the compiler etc.

          I happened to have a contact there and I raised holy hell about it – pointing out that if college courses couldn’t afford
          this stuff for students, guess whose parts weren’t going to get design-in when those guys got real jobs?
          Managed to get the basic kits down under $100, free assembler and a widely pirated (wink..thanks Keith/Brian) C compiler…

          One wonders what some of those guys think – FPGA stuff has only joined that club of affordable stuff recently, and I’m as yet not real impressed.

          Of course, as a consultant, all this was a constant issue as the people providing this stuff wanted to know *my volume* or *my gross* or *my employee count* and blew me off when those numbers were close to 1.

          Of course, they simply gave this stuff to the big guys for free, so I started getting all my toys via customers who “got it” that we needed to play with stuff not yet on the design-in horizon just to stay up with the developments.

          But thinking your tool (software for example) dept is supposed to be a profit center is stupid. I’m supposed to pay up to $10k for the _privilege_ of designing in your part? Really?

          FWIW, I have some of those cheap tweezers, and they’re nice for what they do. I often use them with the diode func in the ohmmeter to simply test leds very quickly, it’s a lot more facile than the usual test probes for that.

          1. “But thinking your tool (software for example) dept is supposed to be a profit center is stupid. I’m supposed to pay up to $10k for the _privilege_ of designing in your part? Really?”

            Yeah! I remember as the T-shirts with slogans fad was in its infancy (early 1970’s) and Coca-Cola sold T-shirts with their logo for ~5 times the price of a regular T-shirt.

            “Wait a minute. You want me to PAY to be a walking billboard for your product?”

          2. No reply link below the question Todd, but yes, your timeframe is correct. Keith liked archery as a check if it’s the same one. Brian worked for sales in the DC area. Keith was um, much further south.

          3. Thank the Arduino for the appearance of reasonably priced eval boards. When all those kids showed up in EE departments and wanted to do everything with an Atmel chip it scared the holy bejeezus out of the other vendors. The MSP430 LaunchPads for $4.30 showed TI got the message.

            Now, if someone disagrees with the project team choice, they can afford to buy an eval kit on their own nickel and with a little bit of personal time invested, be ready to fish the project out of the frying pan if things go wrong. A big win for all concerned.

    2. No kidding about the small type and parts. I have at least 5 pairs of “headgear” goggles scattered around the house and in the different shops. And copious amounts of light.

      BTW, a great old fart trick I came up with for great light on the cheap. Those plastic E27 lamp base you can get on a popular auction site 10 for under $5 and a case of 40 of the 9W LED lamps from a popular dollar store that will ship to your local store for free. Screw 10 of the sockets to a 2×4, wire them bus style and hang them like a fluorescent tube fixture. 10 more watts (90 vs 80) but a lot more light, and it comes on right away even in subzero temps, and they can take some abuse, ie, you can bang things into them without popping them.

      Hell, I can still recall the first transistor I ever played with, the CK722. I think it was a Raytheon part. They came in little boxes like a peanut tubes.

  2. With the tweezer probe (as opposed to the tweezer meter) the longer leads (the length of which weren’t mentioned) will add additional stray capacitance, resistance, and RF reception.

  3. For those in the US, the Mastech MS8910 is almost identical and available domestically:

    Totally worth the money. They work exactly as advertised. The only drawback I found was that the gold-plated tips (of which a second set was included) aren’t very sharp, and don’t align very well; it takes a little extra dexterity to measure small SMT passives.

  4. I totally second Jenny’s review on the el-cheapos. They are crappy tweezers — made out of stamped metal and bendy, but if you don’t have a pair of SMD tweezers, they’re definitely better than nothing, and they cost almost nothing. I use them infrequently, but I do use them. If you don’t already have better, get these.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.