Handheld meter robustness testing

[arcitech]

I think this could require big changes to a meter's front-end, but I'd love to see if the FLIR DM92/3 would "come-a-gutza" under your hands! At this level it competes with Fluke, so if we could get Flir to send you one, it would be nice to know if the switch can take a good beating too. I bet you'd knock it out with the grill starter and send them back to the drawing board 

For what it's worth, a US-based T&M shop has DM92 meters available at $179+shipping on eBay, and (not that it matters to Joe I'd suppose) has confirmed that their shop is an authorized FLIR distributor. It's a far cry from their (own) website's listing at $299. Maybe for this price, it's worth a shakedown..?

(I've avoided links and name of the shop in hopes of not jeopardizing authorized distributor standing; I certainly don't claim to know the rules, but would imagine those who do are likely under NDA, so I'll assume putting names/links on blast would be somewhat irresponsible.)

[paulbt]

Hello!

I searched on this forum for "multimeter input protection", but I could not find anything related other than this topic.

I have a crappy Axiomet dmm with no input protection. I wanted to have some fun with it so I cut some traces and added in series with V/ohm input a 2W 1K resistor, a 1K PTC and a MOV back to COM input.

After this, voltage measurement is 'good' as before, but resistance measurement is affected by the added components. No surprise for me, when I short the leads I get ~2K reading.

I watched again Dave's video on this, but I could not understand how they manage to read the resistance correctly and to have overload protection at the same time.

Can anyone please explain it for me?

If you know any discussion about this on the forum, please post a link here.

Also, please see the attached pictures.

[Chance92]

After this, voltage measurement is 'good' as before, but resistance measurement is affected by the added components. No surprise for me, when I short the leads I get ~2K reading.

I am not quite sure, but my guess is you need to recalibrate and adjust your multimeter to compensate the additional resistance of the additional components.

[paulbt]

After this, voltage measurement is 'good' as before, but resistance measurement is affected by the added components. No surprise for me, when I short the leads I get ~2K reading.

I am not quite sure, but my guess is you need to recalibrate and adjust your multimeter to compensate the additional resistance of the additional components.

I was thinking about calibration/relative/delta stuff, but this needs to be done way too often, that additional resistance is changing with ambient temperature or overload conditions.
Anyhow, I don't really care about my dmm, I will use it only for voltage measurements when needed, I have other safer dmm on my bench.
I just have an opportunity to learn something. Seems like Dave did not explain it. That's why I'm asking...how do they do it?

[SeanB]

The resistor and PTC has to be on the current feed line, not the voltage sense line, which is already protected by the resistors and the clamp transistors there. You need to move them so the voltage sense is at the input, not after the PTC. that way the extra resistance is not part of the resistance measurement, but just reduces the compliance voltage slightly in resistance mode, but the measurement is still accurate. Look on the Fluke input and you see there are 2 paths from the input jack, one is the current for the resistance range to use, along with continuity and capacitance, and also for the mV range, while the other path is used to read voltage on the jack in all those modes. you need to separate those and put the protection in the current path alone, the other one already has protection.

[joeqsmith]

I have a crappy Axiomet dmm with no input protection. I wanted to have some fun with it so I cut some traces and added in series with V/ohm input a 2W 1K resistor, a 1K PTC and a MOV back to COM input.

I've done this a few times.   My question is, how are you planning to validate your changes?  Lets assume what ever you come up with doesn't fuck up the measurements.  How are you planning to prove that your meter is now more robust or "safer" as you put it?   

If the only goal of chopping up the meter is for learning,  I suspect you would be better off playing on some breadboard and learning how a meter works.  From there you could learn how the protection circuits work.

Here's a whole series on my mods to low cost meter.   

Starting out


second attempt


14kV or bust


Showing final mods

[joeqsmith]

Having fun with a very old NST and a few parts salvaged from damaged, non-repairable meters.    I have a 121GW that is in very rough condition along with that last Keysight meter that can't be repaired.... 

[joeqsmith]

Some time ago Dave posted:
 

What happens when you apply five thousand volts across the range switch of a cheap ass multimeter?  I'm glad you asked

I wonder what happens when we apply 12kV across the range switch of a few expensive multimeters.   I have a couple of them that are beyond repair that we could use to help answer this question.

[Fungus]

Would the Fluke 101 take that for a couple of seconds? 

[joeqsmith]

I'm not sure what this transformer puts out during startup.  Maybe start there and design a way to program the number of AC cycles.     Then again, I doubt many of us would try to directly measure such a transformer...   Oh wait, we have had people post about directly measuring their MOTs....  Never ends well.  

[2x2l]

It even says right on the box:
Retool Your Expectations

 

zing. but seriously, real talk - im absolutely devastated by how far HP fell. gender equality for all - carly fiornia proved that women can be as savage as men in business. she managed to take a marvelous, competent company (from the health sciences to VMS/nonstop banking mainframes -- and everywhere in between) and fracture it off in search of short-term profiteering and performance bonuses. i digress.

that being said, ebay a fluke 101, fluke 107 for $120ish shipped (wait for the price dips, the 101s are sub-50USD often).


hey joe, can you test the NGK low-emi plugs and see how meters respond to those HV EMPs? (i.e. the standard "meter resets", or what have you)

[joeqsmith]

hey joe, can you test the NGK low-emi plugs and see how meters respond to those HV EMPs? (i.e. the standard "meter resets", or what have you)

Depends what you are asking.  First, I am not sure what these low-EMP plugs are.  You should have provided a datasheet or at least a part number.   Plugs do not come in one size.  Depending on how you want to test them, my jig is for a 12mm thread / 1.25mm pitch.   I have a few different wires/boots/coils/ignitions that I can test with.   

I assume you are asking if your plugs would cause less meters to reset.  This may be very difficult to quantify.  Maybe a better test would be to look at the radiated emissions from it.   The problem with this is I am not sure how I would measure it.  The source is enough to knock out that crappy USB bus from 5 feet away or so.   

While you search for  data on the plugs you want tested,  consider that the wires I use are around 50ohms / foot. The plugs I show are >> 1k ohms.    You also need to consider that the emissions will be dependent on gap, pressure....   I have only tested with nitrogen. 

Give it some thought. 

***
If we were to look at meters rather than trying to measure the pulses directly, I would want you to narrow that down to maybe one or two meters. 

[golftango]

as i said in the main thread for this meter, i'm way way late to this party and just received mine yesterday. i got some other meters which should satisfy any needs for accuracy, but they are huge--the dimensions on paper don't begin to prepare you for the actual size. i freely admit i didn't shop this as rigorously as i usually do. i had already found a couple of great ebay deals on a fluke 289 and a hioki 4281 so i hardly needed another meter.

but those meters (esp the 289) are on the largish side and i wanted a more compact daily driver so i was shopping for a 4-1/2 digit 50k count small meter and optionally bt capability and the fluke 117 and the owon bt41 were only 6000 count and only the owon had bt. i had read and watched quite a few reviews praising eevblog and had recently joined the forum, so when i came across the 121 by accident with a good price and shipped from the usa i jumped on it without much more thought. only after i ordered it did i start seriously researching it.

but putting all that aside, i tend to really baby my electronics (i'm not the target market for your destruction derby videos for sure--but you had the most detailed info by far) and in the next couple of days i'm going to do my best to compare readings among the fluke, the hioki, and the eevblog and if the 121 is anywhere near the ballpark of those i'll be well satisfied. and the bt on the 121 means i won't have to depend on the fluke internal logging since it has no way of connecting to mac or ios even with the expensive and touchy accessory. /guy

and let me say i have no need for a really good meter--i have a $40 fluke 101 and a hioki 'card' meter both of which, combined with an outlet tester or a clamp meter, would meet most of my needs. but again, i'm a gadget collector and a ham so i appreciate nice sturdy accurate devices.

at any rate, i'm one of those nerds who reads every scrap of documentation, and with the advent of youtube, try to find the patience to sit through videos although i'm not much of a visual learner. and compared with other devices there's not that many videos on the 121gw and, (ass)uming you're the joe smith on youtube, your videos are by far the most detailed of all.

i've now watched through part 6 and learned to avoid methanol (!) and noted in your summary around 56:20 that you say (paraphrased): 'personally, i think this meter has way too many problems to be considered anything more than a gimmick. i think the real selling point is this logo (circles the eevblog logo) and if you look beyond that (something about a ?grill starter? (which i never understood what it was when you demo'd it)) ... you have to believe that uei could do a better job ... and this meter is not that robust'.

my meter came with fw v1.22 which i updated to v2.05 first thing. next i checked the bt using the ios meteor app and that process was seamless and the app works well. i have some modest components i'm going to use for reference coming in and then i plan to compare the 121 against a couple of those supposedly more accurate meters.

so i guess my question is, how can i tell if the particular sample i have has had some or all of the problems you observed corrected? since it came with v1.22 i don't have much hope though. and thanks for the videos even though about 75% of your tests i'll never have to worry about unless there's an electronics apocalypse in the future or i end up going to a ham radio field day!

/guy

[golftango]

also, i i noticed a couple of posts earlier you replied to someone: "im absolutely devastated by how far HP fell. gender equality for all - carly fiornia proved that women can be as savage as men in business. she managed to take a marvelous, competent company (from the health sciences to VMS/nonstop banking mainframes -- and everywhere in between) and fracture it off in search of short-term profiteering and performance bonuses. i digress."

i 1000% agree with this! i was a radioman in the navy from 1970-1980 and you couldn't fling a frog without hitting hp test equipment. about the only other ubiquitous brand was the simpson analog vom. we had an hp cesium beam clock at the satellite earth station i worked at in australia and hp would calibrate those in oregon and buy a plane ticket for it and the tech who hand delivered it. they cost like hundreds of thousands of dollars but were required in order to calculate the doppler shift back in the pre-geosynchronous days when the 'birds' really 'flew'.


i learned programming with the hp-55 calculator and on the carrier cic dept they used the hp-97 (?) with the card reader to match up sonar 'fingerprints' to subs and surface shipping. hp was at the pinnacle of tech and there's a reason jobs and wozniak worked there. sadly, in the 80s they wouldn't have wanted to say they ever worked there. first they started making their calculators in malaysia and thailand and singapore and at the time we thought they'd totally gone to shit. but let me tell you that i have quite a few of those calculators which are now 40-60 years old and despite us thinking them shit back then, they far surpass anything being built today.

oh well, i could go on forever, but it was heartbreaking to see such a famous company go tits up.

[joeqsmith]

...
so i guess my question is, how can i tell if the particular sample i have has had some or all of the problems you observed corrected? since it came with v1.22 i don't have much hope though. and thanks for the videos even though about 75% of your tests i'll never have to worry about unless there's an electronics apocalypse in the future or i end up going to a ham radio field day!

/guy

Guy,

I saw your comment on YT and decided to check in.   Yes, I have dialed back my usage of this site as most of the posts now pertain to topics (religion, politics, race)  that I have no interest in reading.   Looks like the pictures are again screwed up as well.   Sad.

To your question, I would start by asking yourself is what I showed even important to you.  I knew of most of the problems with the 121GW before it was released.  I waited a full two years after its release before I reviewed the meter just to give them the benefit of the doubt.   Most of what I saw in the released product was what I had uncovered with the prototype during my initial testing.   I think most of us knew switch wear would be a factor as  people had posted various design changes.   There have also been several posts of owners having problems with the switch. Cracking plastic has also been an on-going problem.  I believe two of mine now have cracks.   So it seems if you recently purchased one, you would have had an idea of what you were getting as far as quality and there shouldn't be any surprises.   

You could easily check the switch for example.  I provided the board thickness of mine.   Just use your eyes and see if it uses a shim.  What do the contacts look like.   Firmware wise, I gave up following when it became apparent that wasn't something in their wheelhouse.    Maybe it's the greatest product out there now.  I really have not been following it, nor do I use the one that I used for my non-destructive tests.   

I did write some software for the BLE and once I sorted out my mistakes, it seemed to do a reasonable job.  I don't know if they ever did provide more details in the manual about using the meter to measure power.   I did walk KainkaLabs (youtuber) through the problem and how to work around them.  They made a video about it if  your are interested. 

Guessing your quote about Carly was not mine as it does not look like something I would write.  Basically I could care less if Carley is female, what her skin color is, what her religious beliefs are...  What I do care about is what people bring to the table.  This gets back to what I stated above.  As this site does seem more and more interested in such matters, where I came here for more technical discussions related to electronics.     

Anyway, enjoy your new meter.  There is a lot of information published about it so take advantage of the search engines.   Later

[golftango]

thanks for the response. and indeed, i did get confused on the quote as it was by someone replying to you. i apologize. many thanks for taking the time to reply in detail and i appreciate every tip and point you made. /guy

[EEVblog]

I saw your comment on YT and decided to check in.   Yes, I have dialed back my usage of this site as most of the posts now pertain to topics (religion, politics, race)  that I have no interest in reading.   

Not true. But you do know there are Topic, Thread and even Board Ignore lists, right?

[joeqsmith]

I saw your comment on YT and decided to check in.   Yes, I have dialed back my usage of this site as most of the posts now pertain to topics (religion, politics, race)  that I have no interest in reading.   

Not true. But you do know there are Topic, Thread and even Board Ignore lists, right?

Sorry, not true?  I assume you are referring to my comment of religion, politics... and not that I dialed back my use of the site or that I had seen the OPs comments.   You may have taken that to mean these three specific topics which wasn't my intent.  This is why I had closed with:

...  where I came here for more technical discussions related to electronics.

It's not what topics are being discussed,  rather it's whats missing.  Filters are not going to improve that.  Anyway, hope this clears things up. 

[joeqsmith]

Thinking of this thread and non related topics,  I had a discussion a few days ago (pinned comment on attached video).   The FAQ cut down on much of the questions and it's been a while since someone wanted to troll the channel.  Normally, I wouldn't think anything of it but what's interesting is they post "... as a college instructor of electrical engineering, ...".   The context is great.   After a quick search, I believe this is true.      

Did you attend any higher education?  If so what were your teachers like?  It appears here in the USA, the requirements for working in education change state by state. 

https://youtu.be/zzQ57h2vGV0

[golftango]

Thinking of this thread and non related topics,  I had a discussion a few days ago (pinned comment on attached video).   The FAQ cut down on much of the questions and it's been a while since someone wanted to troll the channel.  Normally, I wouldn't think anything of it but what's interesting is they post "... as a college instructor of electrical engineering, ...".   The context is great.   After a quick search, I believe this is true.      

Did you attend any higher education?  If so what were your teachers like?  It appears here in the USA, the requirements for working in education change state by state. 

https://youtu.be/zzQ57h2vGV0

am i missing something? youtube in chrome only shows 4 comments although it says there are 23 of them and there are about 25 /likes/. at first i thought they might be counting replies, but that's not the case. in any event, i don't see the comment you reference.

as to your question about higher education, were you addressing that to someone or seeking responses from anyone? if the latter, i'm glad to supply one, but it's staggeringly long (tl:dr territory!)

/guy

[joeqsmith]

am i missing something? ...

   Yes, but it's because the OP pulled their comment which deleted the entire chain.  This isn't uncommon for trolls.  I expect most of them are aware World Wide Web means just that and once you post something up on social media, it's there for good.   See attached.   

as to your question about higher education, were you addressing that to someone or seeking responses from anyone? if the latter, i'm glad to supply one, but it's staggeringly long (tl:dr territory!)

/guy

Based on the OP's grammar and attempt to troll the channel,  I wouldn't have guessed they were involved in education outside of maybe attending high school.    A quick search seemed to show otherwise.  This had me wondering what are the requirements for various states when we look beyond the high school level.  A bit of an eye opener.   

My questions were directed towards anyone with a higher education.   Military, university (all colleges call themselves that but you know what I mean), community college, anything goes.  I bet there are some good stories out there. 

Thinking back, I had some really good teachers.  They were all very professional and many came from the industries they taught in.   I had made an attempt to contact one of them several years later just to thank them but sadly they had passed away. 

[golftango]

am i missing something? ...

   Yes, but it's because the OP pulled their comment which deleted the entire chain.  This isn't uncommon for trolls.  I expect most of them are aware World Wide Web means just that and once you post something up on social media, it's there for good.   See attached.   

as to your question about higher education, were you addressing that to someone or seeking responses from anyone? if the latter, i'm glad to supply one, but it's staggeringly long (tl:dr territory!)

/guy

Based on the OP's grammar and attempt to troll the channel,  I wouldn't have guessed they were involved in education outside of maybe attending high school.    A quick search seemed to show otherwise.  This had me wondering what are the requirements for various states when we look beyond the high school level.  A bit of an eye opener.   

My questions were directed towards anyone with a higher education.   Military, university (all colleges call themselves that but you know what I mean), community college, anything goes.  I bet there are some good stories out there. 

Thinking back, I had some really good teachers.  They were all very professional and many came from the industries they taught in.   I had made an attempt to contact one of them several years later just to thank them but sadly they had passed away.

well, i'm outside your target group as i have zero higher education. but i think my story might show the effects of _not_ having it. sorry it's so long, but i try to put in all the pertinent details:

i realized in middle school that i detested being fed bits that someone thought comprised a suitable education. worse, even in the subjects i liked and was willing to try my best in such as literature and history, the pacing was way too slow and i'd end up racing through the textbook and library books on the subject and then being bored for the rest of the school year.

in high school i did find vocational photography and journalism worth the effort, but not worth sitting through nearly all the other classes. and in fact i was still pursuing a photography or journalism job more than a decade later when i got out of the navy which i joined on my 17th birthday---the fastest date i could drop out of high school. when i finished 2nd in my company of 75 on the basic induction tests i confirmed i had at least absorbed enough, on my own or in school, to hold my own. i passed the ged so quickly they wouldn't issue me the certificate until a year or two after i was supposed to have graduated.

but besides photography and writing i've been interested in tech and got my first ham license when i was 16 i think. when i joined the navy i wanted photographer or journalist but due to my scores on tech stuff the navy, in a rare spurt of common sense, made me a radioman and i didn't hate it--it just meant i'd take the navy photography and journalism courses by correspondence instead of a naval school.

i did well in the navy despite my detestation of authority and rote commands and routines and in fact they kept promoting me against my wishes as i have zero leadership qualities. i got the very first satellite class the navy offered in 1971--so new there weren't any navy instructors yet.

i made a huge mistake in leaving the navy after 10 years--8 years and six months short of retirement. but they were promoting me way beyond my leadership capabilities (peter principle anyone?) and at one point put me on an aircraft carrier and froze me there for nearly 3 years where i worked about 18 hours a day on average.

when i got out of the navy i headed to our local newspaper to try to get a job but they lied to me by saying that they wouldn't hire anyone without a degree. but the computer manager caught me (literally) in the parking lot with my car door open and hired me on the spot. and again, i didn't hate it as i had programmed calculators and built the very first pc (altair 8800) from a kit. and this was a hugely lucky event in my working life as i was getting in on the ground floor of the technological and telecommunications revolution. plus, as a huge bonus, i spent about 40-60% of my working time while the computers were processing back in the photo department helping them process film and even going out to shoot upon occasion.

i realize i've digressed significantly (i digress, i breathe) but all that was to point out that i had landed a very good job without any higher education and when i left there 13 years later telecommunications had taken off like a rocket and with my ham and navy communications and computer experience, i took off like a rocket as well and worked for nearly all the major telecom companies ending up at the largest computer services company in the world doing network analysis and all of it without a bit of 'traditional' higher education if you don't count tech schools. i realize that the computer tsunami wave i rode likely made me an outlier though--not sure anyone could achieve that if they started today where the babies have ethernet ports in their cradles.

/guy

[joeqsmith]

Thanks for taking the time to post guy and thank you for your service.    I would say that your military training certainly counts for higher education.   Actually, let me say that I worked with a few good friends that had no formal education outside of what they learned in the military and they were sharper than many I knew that had their degree. 

[EEVblog]

I saw your comment on YT and decided to check in.   Yes, I have dialed back my usage of this site as most of the posts now pertain to topics (religion, politics, race)  that I have no interest in reading.   

Not true. But you do know there are Topic, Thread and even Board Ignore lists, right?

Sorry, not true?  I assume you are referring to my comment of religion, politics... and not that I dialed back my use of the site or that I had seen the OPs comments.   You may have taken that to mean these three specific topics which wasn't my intent.  This is why I had closed with:

...  where I came here for more technical discussions related to electronics.

It's not what topics are being discussed,  rather it's whats missing.  Filters are not going to improve that.  Anyway, hope this clears things up.

You are not correct that when you said "as most of the posts now pertain to topics (religion, politics, race)"
That's simply not true.
Here is a list of the most recent topics as I post this, zero of what you mention.
Yes there is odd topic here are there that might drift into that, but practically all of the forum is electronics related in some way.
If you don't think there are any good electronics topics that interest you, then ok, each to their own, but don't blame it on "religion, politics, race topics".
Start a thread on a technical topic that interests you and watch people join in.

[joeqsmith]

I saw your comment on YT and decided to check in.   Yes, I have dialed back my usage of this site as most of the posts now pertain to topics (religion, politics, race)  that I have no interest in reading.   

Not true. But you do know there are Topic, Thread and even Board Ignore lists, right?

Sorry, not true?  I assume you are referring to my comment of religion, politics... and not that I dialed back my use of the site or that I had seen the OPs comments.   You may have taken that to mean these three specific topics which wasn't my intent.  This is why I had closed with:

...  where I came here for more technical discussions related to electronics.

It's not what topics are being discussed,  rather it's whats missing.  Filters are not going to improve that.  Anyway, hope this clears things up. [/b]

You are not correct that when you said "as most of the posts now pertain to topics (religion, politics, race)"
That's simply not true.
Here is a list of the most recent topics as I post this, zero of what you mention.
Yes there is odd topic here are there that might drift into that, but practically all of the forum is electronics related in some way.
If you don't think there are any good electronics topics that interest you, then ok, each to their own, but don't blame it on "religion, politics, race topics".
Start a thread on a technical topic that interests you and watch people join in.

I guess my response still left you with some confusion of my intent of that statement.  No matter.   It won't change my lack of interest in the topics being discussed and my use of the forum will most likely continue to decline as a result.  It's not a big deal.   I was merely answering the OPs question about my apparent absence.