121GW Multimeter

(9 customer reviews)

AU$325.00 AU$299.00 ex GST

A unique, feature packed Multimeter which has been developed with electronics designers and hobbyists in mind.
This multimeter represents two years of collaboration between EEVblog and UEI.

Out of stock


Designed for electronics use, with unique features such as:

  • Bluetooth connectivity (multi-device capability)
  • Open Source Cross Platform application software (Android + Windows, and more soon)
  • 15V Diode Test Voltage (useful for Zeners + LED strings etc)
  • VA Power measurement
  • Low Burden™ voltage
  • Unique burden voltage display
  • Micro SD Card data logging + firmware updating

Other major features include:

  • Dual 50,000 count display with bargraph
  • 0.05% + 5 Basic DCV Accuracy
  • Auto-Hold measurement
  • 600V CAT-III with independent UL 61010 certification by ETL
  • Safe operation through HRC fuse + TVS + PTC + MOV + Diode Bridge protection

Hardware Features:

  • AD8436 >100KHz True RMS
  • 4 x AA battery powered with 500+ hr battery life
  • Compact design – 84 × 165 × 59 mm (W × L × H)
  • Hackable ST ARM Cortex M3 processor (S-LINK/V2 programmer interface inside)
  • Hycon HY3131 chipset
  • MAX4238 Low Offset Amplifier for current ranges
  • SD Card firmware update
  • Full Open Schematic available
  • 8ppm ADR3412 voltage reference

The meter is manufactured by UEI Test Instruments, a reputable US based designer and manufacturer of high quality test gear. The design work was primarily done by UEI, but with a great deal of design input and direction from Dave. The meter is manufactured in South Korea.

NOTE: The current stock meter from this website is the latest pre-Kickstarter build that has the new PCB (doesn’t require the shim) and larger protection transistors fitted. It also comes with the UEi test leads instead of the Brymen test leads. These leads do not have banana tip adapters like the Brymen leads.

Additional information

Weight 0.75 kg
Dimensions 8 × 15 × 19 cm


Manual - 27 September 2019 Circuit Diagram


Note: When upgrading a multimeter the “.bin” file MUST be renamed “EEVBlog.bin”:

121GW Firmware 2.04
EEVBlog 2.02 EEVBlog2_00 EEVBlog1_58 Beta EEVBlog1_57 EEVBlog1_52 EEVBlog1_26 EEVBlog1_25 EEVBlog1_22 EEVBlog1_21 EEVBlog1_17 EEVBlog1_15 EEVBlog1_10 EEVBlog1_07 EEVBlog1_05 EEVBlog1_04 EEVBlog1_02 EEVBlog1_00

BLE Packet Format

Packet Format V1 Packet Format V2


UEi’s Android App
Android App
Windows App



Report an Issue

9 reviews for 121GW Multimeter

  1. Phil Carey

    A great little meter, as soon as I saw Dave was making this, I had to have one!
    I’m only a hobbyist but I love all the functions this meter has to offer. (Especially the 15v diode mode!)
    I grew up playing about with batteries and bubs and later soldering little circuits as I grew. I only had a small HC – 213 analog meter in my teens and wasn’t really until I got back into electronics 20 something years later, I bought my 1st decent meter, a fluke 87V. Although I love that one I also got the rebadged BM235 from Dave/Brymen also.
    Lastly I got this one and probably haven’t finished yet! ( oh I forgot to mention I’ve also got 2 fluke 115’s and a Uni T AC/DC clamp meter and a BK 878B LCR meter!
    You can never have enough meters, right? lol

    Anyway, after sidetracking down memory lane there, I love the 121GW and highly recommend it to anyone who wants a decent meter.

  2. Paul Belanger

    Is it possible to post a changelog for the firmware versions for this meter? I’d like to know what is updated when a new firmware is released.

    • Seppy

      There is a change log in the 121GW manual.

  3. Lon Larson

    Worth the wait. I love the size, the look, the feel of it, the accuracy, the excellent documentation, and the great design targeted directly at what we hobbyists wanted. Thanks Dave!

  4. Ed H

    To answer Paul, the firmware change log is in the PDF manual. Whenever there is a new firmware, check out the manual.

  5. Sonny Horton

    I unboxed my meter last night, and I have to say that first impressions are excellent.

    The “No BS” packaging is clever, and I love the branding.

    But, this meter is not about marketing fluff. The fabric case is nicely made, and the molded logo is a nice touch. While the interior retaining straps are initially a bit confusing, a quick search on the forum leads you to the logical answer on how they are intended to be used. (Single facepalm.)

    When I opened up the back, I was impressed by how well-fit and finished the injection molded parts are. I used to represent a couple of injection molding companies and I must say this is first-class work.

    Upon removing the microSD, I was further impressed by the generous capacity of the provided card. That’s a place where you easily could have skimped to increase your margins, but you just didn’t.

    When I put the rear of the case back on, I saw that the fit that I appreciated upon removal is so precise that you really have to line up the case to slide it back into position and when you do, you can hear and feel the rush of air passing by that tiny clearance gap between the two parts. It is quite satisfying for a geek like me.

    The firmware update process was easy to understand, fast, and flawless. The function knob feels nice and tight and the buttons feel pretty much like a Fluke or other similar meters. I went through all the functions and everything works as advertised and expected.

    I haven’t done any accuracy checks yet, but I don’t have good enough voltage and current standards to really put it to the test. I will compare it to my 6.5 digit Siglent and my two Flukes (you can NEVER have too many multimeters!), as well as some 0.005% resistors I bought for meter checking.

    The IOS app didn’t fail to impress, either. It set up and connected to my meter without any hiccups or special tongue angle required. The screen is very well designed and quite readable. The update rate is fast as well – I was surprised how fast, actually.

    The PDF manual could use a few minor touch-ups, particularly around the VA measurement – showing the actual lead placement in the diagram would be helpful to the young players, though we gray heads (I don’t wear a beard) can see clearly what to do. Further, the instructions on how to set the date and time don’t tell you how to get from one field to the next. I’m sure I’ll find that in the forum as well.

    I have to say that Dave and UEI have really done a terrific job of putting together a boatload of useful features into one compact, reasonably priced, beautifully constructed package. In a single phrase, it was worth the wait.

    I can’t wait to show it off to all my Amateur Radio friends at lunch next week. I’ll imagine there will be a small flurry of backorders coming your way from here in Arizona 🙂

    Thanks Dave and team!

  6. Kellee Crisafulli

    2018-07-20, I was pleased to received my 121GW a couple days ago, first reaction is very cool 🙂
    I plugged it into a Tektronix 515A meter calibrator to run a fast out of the box accuracy check.
    Tested AC volts at 400hz, 1KHz, 50KHz, 1V to 100V, appeared to be within stated accuracy.
    Tested DC volts 25uV to 100.0V and appeared to be within stated accuracy.
    Test Ohms from 0 to 1MEG appeared to work OK.
    10 Meg Ohms looks a bit “wonky” reading ~9.7 Mega Ohms +- 200K depending how I hold the cable, position of my hands, and if I blink or not (kidding). Other handhelds and my bench meter indicate very close to 10.00 Meg no matter which way I hold the cable.
    As Dave might say “That’s a fine how do you do”, seriously something on the 10M scale appears to have a noise issue, not a show stopper but interesting…
    That’s all the testing I have done so far.

  7. Frederik Büller

    Love it 🙂

  8. Henrik

  9. John Moorhead (verified owner)

    I echo all the positive comments above, absolutely fantastic work, Dave! I’ve already used this meter multiple times over the last two days and with its advanced capabilities I can see expanded usage of this one over my Fluke 87V and my Brymen BM235. I’m going to spend some serious time with the manual exercising all the functions and will probably send you a list of questions/comments. A couple here – I’m wondering if a software option can be added to optionally store a specific preferred default Mode for each selector switch setting as well as the last used Mode as it does now. Also, tried to check my battery voltage per Page 59 of the August 7 2018 manual but am not getting the BAT indication with SETUP. I tried this with the original 1.22 firmware and also still see this in 1.25 after upgrade. The really cool thing about this meter is it is all configurable via software upgrades and I’m sure additional functionality and features will be added down the road. To quote you, “Winner Winner Chicken Dinner!!!”

Only logged in customers who have purchased this product may leave a review.

You may also like…