EEVBlog 121GW Discussion thread

[AVGresponding]

Couldn't you buy an old Android phone just for BLE logging purposes?

[VinzC]

That doesn't sound very practical nor realistic. Besides it's not like we've never seen systems self-lockup because no updates are available or the hardware is incompatible or the user must upgrade their "contract" or... whatever reason. Short: this is not viable in the long run, not even in short terms.

[Gyro]

Aren't manufacturers / distributors required to support the advertised features of their products for some reasonable time after purchase - at least for the warranty period, and under most country's laws, for the 'reasonable expected life of such a product' (I can't remember the exact EU / UK wording) but I'm sure Australia must have something similar.

As the product is still being offered for sale, the elapsed time is still at zero...

[2X]

Hi,
I have the multimeter 121GW and when I measure this two square pulses (produced from Arduino UNO) at the below image the multimeter shows me 49.9Hz, 50% duty cycle, but is shows me 10ms period. Why didn't show 20ms where is the right... it seems like to measure the half period. Does anyone knows why?

[EEVblog]

So I tried to install this, even the APK from the gitlab source, no luck. I got this error. "App not installed as app isn't compatible with your phone".
Same with meteor for 121GW, "This app isn't available for your device, because it was made for an older version of Android"
Phone: S24 (Android 14)
Guess that's one of the major feature that I cannot use :/

The Meteor app has been recently updated for the latest android version.

[EEVblog]

I have the multimeter 121GW and when I measure this two square pulses (produced from Arduino UNO) at the below image the multimeter shows me 49.9Hz, 50% duty cycle, but is shows me 10ms period. Why didn't show 20ms where is the right... it seems like to measure the half period. Does anyone knows why?

You are correct, it measures the positive pulse duration and not the period of the frequency. It looks like nobody picked up that issue in the manual 
So it should be called "Pulse Duration" or something similar.

[EEVblog]

I have updated the manual to correct the Period measured to Pulse Width.

[Candid]

Where si the link to the new manual? At the shop I got only an older one.

[VinzC]

https://duckduckgo.com/?q=121GW+manual

First result, literally: https://www.eevblog.com/files/EEVblog-121GW-Manual.pdf

[Candid]

The manual from March 2020 is not a problem to find, it is in the shop at the product ;-) I meant the new manual.

[Kean]

The newest manual has been uploaded to the shop, but Dave forgot to update the "Last Revised" date on the front page so it still says 1 March 2020.

Skip to page 2 and you will see in the page heading it has been updated on 24 February 2025.  Also on page 8 it lists the changes made in the latest revision.

[EEVblog]

The newest manual has been uploaded to the shop, but Dave forgot to update the "Last Revised" date on the front page so it still says 1 March 2020.
Skip to page 2 and you will see in the page heading it has been updated on 24 February 2025.  Also on page 8 it lists the changes made in the latest revision.

Yeah, oops, fixed.
The only official place for the manual is on the store page.

[hp3310a]

Yeah, oops, fixed.
The only official place for the manual is on the store page.

The documentation link on https://eevblog.store/products/121gw-multimeter goes to the old March/2020 version.

[EEVblog]

Yeah, oops, fixed.
The only official place for the manual is on the store page.

The documentation link on https://eevblog.store/products/121gw-multimeter goes to the old March/2020 version.

Thanks, fixed.

[Micah Lindstrom]

While we're on the topic of small things in the manual anyway, I figured I'd mention a few I noticed while perusing it today.

• p65 typo, it says "Littlefuse FLU011" but should be "Littelfuse FLU011"
• p9 says "This manual is written for version 1.07 of the 121GW firmware." It would be better to say, "This manual is written for the latest version of the 121GW firmware shown in table below."
• p7 has DD/MM/YY date format but then p8 switches to DD/MM/YYYY. Fwiw, I personally think the ISO 8601 date format YYYY-MM-DD is pretty smart. Of course none of this is a big deal, it's just weird to me to switch formats halfway through the list.
• I was initially confused by the sentence, "The following specifications are given in SI units with their accuracy notated as ± (% of reading digits) + (number of digits) unless otherwise indicated." I was confused because there were zero specifications with that format in the following General table. Eventually I realized the sentence is for the tables starting 2 pages later. Imo the sentence should be moved to two pages later.
• It would be to have a date listed for the latest firmware update. I'm having trouble telling how old firmware version 2.05 actually is. If the firmware is much older than the manual, that is good evidence of solid firmware that's well-tested and stable.
• p16 notes lithium batteries may cause issues. What about NiMH? I'd guess no problem, but would be nice to see it mentioned as well.
• p18 footnote for DC 50 µA range notes something should be "REL'd out." Is that referring to the section "RELATIVE MEASUREMENT (REL)"? That section only mentions use for resistance measurements, not current. And the section on current measurement doesn't provide additional details either.

Again, none of these are a big deal. I don't own a 121GW, but it's a very intriguing product and I'm strongly considering it. Especially because I ordered a Brymen 789 seven weeks ago from WElectron, but it's still backordered, and I'm getting impatient to have a new toy to play with 

[EEVblog]

While we're on the topic of small things in the manual anyway, I figured I'd mention a few I noticed while perusing it today.

• p65 typo, it says "Littlefuse FLU011" but should be "Littelfuse FLU011"
• p9 says "This manual is written for version 1.07 of the 121GW firmware." It would be better to say, "This manual is written for the latest version of the 121GW firmware shown in table below."
• p7 has DD/MM/YY date format but then p8 switches to DD/MM/YYYY. Fwiw, I personally think the ISO 8601 date format YYYY-MM-DD is pretty smart. Of course none of this is a big deal, it's just weird to me to switch formats halfway through the list.
• I was initially confused by the sentence, "The following specifications are given in SI units with their accuracy notated as ± (% of reading digits) + (number of digits) unless otherwise indicated." I was confused because there were zero specifications with that format in the following General table. Eventually I realized the sentence is for the tables starting 2 pages later. Imo the sentence should be moved to two pages later.
• It would be to have a date listed for the latest firmware update. I'm having trouble telling how old firmware version 2.05 actually is. If the firmware is much older than the manual, that is good evidence of solid firmware that's well-tested and stable.
• p16 notes lithium batteries may cause issues. What about NiMH? I'd guess no problem, but would be nice to see it mentioned as well.
• p18 footnote for DC 50 µA range notes something should be "REL'd out." Is that referring to the section "RELATIVE MEASUREMENT (REL)"? That section only mentions use for resistance measurements, not current. And the section on current measurement doesn't provide additional details either.

Again, none of these are a big deal. I don't own a 121GW, but it's a very intriguing product and I'm strongly considering it. Especially because I ordered a Brymen 789 seven weeks ago from WElectron, but it's still backordered, and I'm getting impatient to have a new toy to play with 

Thanks.
Changes made.

[Micah Lindstrom]

It fits UEI's magnetic hanger, but I don't actually sell that.

This one, I assume:
https://www.ueitest.com/products/accessories/amh1

Yep, I think that's the one.
Could probably make a little slide in adapter that took some sort of standard size magnet (say 10mm dia) and allowed it to fit snug inside.

Maybe add the UEi AMH1 to the manual too? Right now the manual just notes "magnetic hanger" is available as an optional accessory, but it took me awhile to find those comments above saying the UEi AMH1 is (probably) the right strap to buy.

It's about $15+shipping from what I'm finding online, so not the end of the world if I bought it and it didn't work. There are two other strap variants, the AMH2 and the AMH3, but from the pictures it's pretty clear those won't work.

• UEi AMH1 https://www.ueitest.com/ECommerce/product/amh1/magnetic-hanger-digital-multimeter-series
• UEi AMH2 https://www.ueitest.com/ECommerce/product/amh2/magnetic-hanger-dl569-dl579
• UEi AMH3 https://www.ueitest.com/ECommerce/product/amh3/magnetic-hanger-dl589-dl599

I also found beanflying shared some 3D printed options in this thread, but I don't have my own 3D printer. I also don't totally understand why print a clip when the strap already comes with one. Maybe they found a 3rd-party strap somewhere (not UEi AMH1) but still needed a compatible clip.

• June 12, 2019 beanflying clip for webbing strap magnetic hanger (final form, scroll up for previous revisions) https://www.eevblog.com/forum/testgear/eevblog-121gw-discussion-thread/msg2479284/#msg2479284
• June 12, 2019 beanflying clip for inset countersunk magnetic hanger (final form, scroll up for previous revisions) https://www.eevblog.com/forum/testgear/eevblog-121gw-discussion-thread/msg2479518/#msg2479518
• June 13, 2019 beanflying additional https://www.eevblog.com/forum/testgear/replacement-knobs-feet-and-fittings-for-test-equipment/msg2481618/#msg2481618

[Micah Lindstrom]

I just got mine earlier today. I'm pretty happy with it so far, but I haven't really gave it any purposeful use yet.

In regards to the question about the straps, I'm pretty sure they're for securing the multimeter and leads like this. I also see that there's another strap on the back, Dave must have liked that multimeter strap patent so much, that he wanted one too

Oh, and it would be great to have a picture like this too on the meter and case product pages, and in the manual. A picture and description showing how to use the straps in the case. I was wondering the same thing and again, just happened to stumble across it in this forum thread after not being able to find anything in the manual.

[Micah Lindstrom]

...On the subject of the backlight, how about an option to light it up along with (or instead of) the beep in continuity test mode? It's a small feature that would make a big difference to people with hearing loss, or just for when you're trying to troubleshoot a dicky connection without annoying everyone else in the room.

...The BM235 [and BM789] flashes the backlight in continuity mode - and it does so whether the backlight is off or had been turned on.

The 121GW did not get this feature, correct? I took delivery of a 121GW and a BM789 this last week. On the 121GW I figured out how to set beep threshold at 30Ω or 300Ω and how to invert beep behavior for testing wires, but I'm not seeing anything in manual or SETUP menu to replicate the flashing backlight feature.

[EEVblog]

The 121GW did not get this feature, correct?

Correct. It doesn't have that feature.

[Micah Lindstrom]

Thank you for confirming about the backlight during continuity.

I think I found another typo in the manual. Minimum DC V range is 50mV, not 5mV. The 1μA resolution is correct. Only realized because I was thinking about counts, and wondering why in the 5mV range I was only getting 4 digits instead of 5 digits.

It's also not clear to me why it has a footnote for that range saying, "Using Relative Mode, zero with shorted test leads." It seems to work fine in the autoranging setting too. I can certainly understand how relative mode will become more important at smaller voltages, but the way it's written made me think it's some special mode to unlock with this special procedure. The same footnote is on the ohms range.

[EEVblog]

I think I found another typo in the manual. Minimum DC V range is 50mV, not 5mV. The 1μA resolution is correct. Only realized because I was thinking about counts, and wondering why in the 5mV range I was only getting 4 digits instead of 5 digits.

Thanks, fixed.

[beanflying]

I also found beanflying shared some 3D printed options in this thread, but I don't have my own 3D printer. I also don't totally understand why print a clip when the strap already comes with one. Maybe they found a 3rd-party strap somewhere (not UEi AMH1) but still needed a compatible clip.

I own several sewing machines and am not afraid to use them  Also back when I made those models I was still learning how to drive Fusion360 more efficiently so an excuse to practice with a useful outcome was worth it.

The cost of making either the magnetic or webbing version if you own a printer will be well under $1 or these days even get them made by an online service next time you order some PCB's. No need for a strap either just use a lump of decent cord would do it.

[J-R]

I can confirm the AMH1 is the correct magnetic strap for the 121GW.  I picked one up a couple years ago.  It's a little bit anemic mostly due to the fact that the magnet is covered with plastic instead of a more rubberized material.  So it wants to slide down whatever it's attached to.  Also, the 121GW will not fit properly in the carry case with the strap inserted.  So you have to remove it first.