121GW Multimeter

AU$285.00 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.

37 in 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 post-Kickstarter build that has the new late 2019 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 but are still top quality silicone leads.

Additional information

Weight 0.75 kg
Dimensions 8 × 15 × 19 cm


121GW Manual – 1st March 2020
Circuit Diagram


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

121GW Firmware 2.05
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



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