To have won the grand prize for the Experimenting with Thermal Switches design challenge was a great honour - it was the first such design challenge I had ever entered. But I couldn't help but give the Experimenting with Current Sense Amplifiers design challenge a go as well, as I very much have an interest in test and measurement and having something to do with the Raspberry Pi would be nice (even if, due to stock shortages, I had to use one of my own). This one actually came at an inopportune time, as work was ramping up and I was suddenly sent interstate for almost two whole weeks, overlapping with the challenge itself.
I was so convinced that I wouldn't win anything, I had practically written off my chances of getting anything. The competition was strong and prolific - all I could do was try to stick to my recipe of providing comprehensive, polished and detailed blogs. In the end, it was an honour to be chosen as a runner-up for the Experimenting with Current Sense Amplifiers design challenge, making it two "wins" out of two.
The runner-up prize was the Smart Tweezers ST-5S-BT2 "High Performance LCR Meter". This seems to be a product of Ideal-Tek, however, the box seems to indicate that the probe tips are from Ideal-Tek, but the company behind them seems to be Advance Devices Inc. As noted by the model number and the Bluetooth logo on the box, this is a Bluetooth Low-Energy enabled device, but it is not the one that is bundled with a USB receiver (they have several different SKUs).
This one actually arrived on the same day as the laptop did, with many thanks to srutledge for getting it sent out. For the most part though, I have been accustomed to using my Keysight U1733C Handheld LCR Meter for go/no-go component assessments, which while I wouldn't class as "high precision" at 0.2%, has been plenty accurate for my needs. The handheld meter is nice for through-hole components and works fine with test probe leads, but the tweezers definitely add a new dimension of convenience for SMD and in-circuit probing.
It was surprising to me to check out the price for the ST-5S-BT2 on the local Australian element14 site - it's listed at AU$800.68 putting it up there with the mainstream brands. Of course, chip shortages and inflation have driven up the price of everything - the U1733C which I have is listed at AU$723.00 which is quite a bit more than the AU$421.00 back in 2014 (which I bought using an element14 Gift Voucher)!
The unit is packed in a flip-open magnetic-closure display box. Inside is a warning to discharge components prior to test - always a good idea to avoid causing damage to your instruments. All supplied parts are nestled inside a foam insert, keeping them safe in transit.
Included is the Smart Tweezers themselves, protected inside a hard plastic case, a USB charging cable, a USB memory stick with the manual and quick-start guides, two quick-reference cards and a certificate of calibration. The listed basic measurement accuracy ranges between 0.2% to 2.0% and the maximum measurement ranges are listed. It is hard to get an apples-to-apples comparison, but I feel the U1733C bests these accuracy levels, as the U1733C has more ranges which also means more versatility for measuring things like large electrolytic capacitors. Sure, you probably wouldn't ideally use a tweezer to measure an electrolytic capacitor, that's not to say that you can't ... either through manipulation of the tweezers or connecting jumper wires to the tips.
But what the U1733C may have for accuracy, the ST5S-BT2 fires back with Bluetooth Low-Energy connectivity, integrated rechargeable battery, small size and delicate tips for one-handed surface-mount component probing. Depending on your priorities, perhaps if SMD is important to you (and it seems to be more and more important with each passing day), then the convenience of not needing to go two-handed to probe is perhaps going to sway your decision.
For the most part, it may look like an ordinary set of tweezers with a "chunky" bit on it - and when holding it in the hands, that's exactly how it feels. It seems to be moderately robust and comfortable to hold on the knurled, rubberised arms of the tweezers. The unit at the top has an OLED display and a four-direction joystick with centre-click as its only user interface device. The joystick isn't exactly the most friendly to use - mine seems to be a little stiff in one direction, sometimes taking a few attempts to register input. The unit is screwed together at the top and at the tips, suggesting the tips can be interchanged or replaced as necessary. That being said, as the unit has an integrated battery, it will have a limited lifetime and may need a "hack" replacement in the future.
The key attraction is the gold-plated Ideal-Tek tips, which are pretty fine and sharp enough to hurt someone or something if you mess-up and slip ... not kidding! The fine tips are nice for exerting pressure to (hopefully) puncture through any surface flux/oxide layers and get a good connection, however, when the tips are bought together, there is a slight offset which makes it a bit tricky picking up the smallest SMD components and not accidentally "flinging" them across the room. It wasn't too bad for "regular" sized 0603/0805 sized parts. It's a good thing the unit comes with the hard case to keep the tips protected.
The OLED display, while relatively small, seems to be well utilised with plenty of icons and small text to boot. I can see some people having difficulty reading the smaller parts of the display, but it is okay for me. The display seems to update around 2Hz, a little slower than most DMMs, with a noticeable flicker as it takes another measurement. To some extent, it reminds me of the microcontroller-based component testers which can be had cheaply, but more accurate.
By default, it seems to be "fully automatic", so it will set the type of component automatically and manage the frequency as well. Changes in test parameters can be effected with the joystick directions. Unfortunately, the way the results are displayed are rather limited compared to some other LCR meters - for example, I didn't find any "phase angle" display for example, although series resistance and dissipation factor are perhaps good enough for general use.
There is a menu configuration interface - the maple leaf honours the Made in Canada nature of this product. The firmware appears to be built 18th March 2021, Version 1.1.12.2T03 Build 993F.
The product does show its age slightly, with the micro-USB B connector for charging.
In case you're interested, the supplied USB appears to be 128MB to the host system and is made of a no-name controller paired with a Hynix eMMC chip of unknown native capacity.
Bluetooth connectivity requires the installation of the Smart Tweezers LCR Meter Bluetooth Companion application and activation of the Bluetooth option in the menu. Turning on Bluetooth seems to keep it running even when the meter has gone to sleep after its configurable time-out period, which I suspect may drain the battery over time.
The first thing the app will do is to scan for devices. Once the device is found, it is as simple as tapping on it to pair with the tweezers.
The Measure page provides a paper-tape like view of the measurements taken by the meter at each measurement interval. Configuration of audio alerts can be performed through the app - this is much easier than trying to fumble around with the on-device menus. It is also possible to store profiles with the app, but I didn't use this.
The operating mode can be configured through the app as well. Each of the parameters can be selected from a fixed list of values -
Finally, the About page provides information on the version of the app.
I suppose the app can be quite useful for logging values of individual components or for changes over time, but I would probably suggest not holding the connections by hand! It does help with the small screen, as you can use your phone's larger screen to see the values and the latency is minimal.
In the end, I am thankful to have another useful tool on my bench - for SMD devices, this is just so much quicker and easier to use compared to the U1733C. Many times, what I need is just to know the value (roughly) and a go/no-go indication on the health of the component, so the Smart Tweezers can definitely fit the bill. For THT devices, it's not always ideal for getting an easy contact with devices to use the tweezers, but perhaps some clip-on jumper wires could serve as a probe (although introducing a bit of error). However, in my case, I would probably prefer to use the U1733C instead. I guess I've just been spoiled for choice, having recently reviewed a truly precision high-performance LCR meter. Too bad that one has to go back to the company as it was on loan, but I'm plenty happy that I have both my Keysight U1733C and the Smart Tweezers ST-5S-BT2 for my component checking needs. Thanks element14 and Analog Devices / Maxim Integrated!
Now that all of this is out of the way, I should really focus on the Experimenting with Thermistors design challenge ... others have already started to blog and I'm still here talking about my winnings. Tsk tsk!
