Author Topic: Cheap multimeters... what is so bad?  (Read 32974 times)

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Offline Lightages

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Cheap multimeters... what is so bad?
« on: July 11, 2013, 06:01:29 pm »
I am starting this thread to debate the cheap multimeter. In another thread some questions were raised and instead of hijacking the other thread I thought I would answer the questions here and start a discussion.

The questions started out in this thread here:
https://www.eevblog.com/forum/testgear/multimeter-sale-too-good-to-be-true-mastech-ms8268-digital-acdc-automanual-r/msg260292/#msg260292

A recap of the questions posed:

Quote
Why is a cheap multimeter a bad thing? I have a 15 euros one and honestly it does the job quite well.. It measures resistors, caps and voltages quite well... Why do i need a more expensive one? All the voltages I work with are <=12 and 90% of them <=5volts.. and if the voltage fluctuates a bit then I use my USB oscilloscope and problem solved :)

Seriously, what is the problem with cheap multimeters?

Quote
Even if your multimeter is super accurate your components have tolerances of a 2%, 5% and even 10%, ... who cares about the 3rd digit?
         - If you care then probably your design is not robust and will just work in your lab and with that particular IC :)

High voltages, seriously, do you ever work with voltages >=220V? I'd say we work with voltages <=24Volts! most of us probably don't need all that safety stuff...
         - shall we do a poll?

In my opinion a cheapo multimeter should be good for 95% of us....

Quote
So if is safe to say that for anything that is not >=110V or that is high precision electronics, a cheapo multimeter will do the job?

I am rather surprised how many people here are encouraging people to buy rather expensive equipments without even asking them what do they plan to use it for!

If after watching the videos and reading the other discussions you still aren't sure why cheap meters are not worth buying we should have a discussion here to clear things up.

First, cheap meters do have their place, but they cant be too cheap. You can buy some really cheap multimeters for $5 or less. I hope I don't need to point out to anybody that these are going to be junk and will not be reliable in any way. So I will not try to disprove the "value" of really cheap meters.

So why are some relatively expensive meters pushed on people? Well if you do anything other than poking your meter leads inside battery powered and low power AC connected equipment, then you are beginning to expose yourself to some random hazards. These hazards can be lightning strikes kilometers away causing a surge on the mains, a bad appliance somewhere in your house causing spikes on your wiring, even a faulty transformer on the utility pole outside. In other words you are playing with some potentially very hazardous conditions when you start poking around house wiring and the power distribution box in the house. So if you are going to even consider doing anything like this then you better have a good safe meter. $15 meters are not going to cut it.

Now that we have dispensed with the garbage meters and the higher end meters, lets get on with talking about the "cheap" meters. Not all are garbage but all are not safe for poking around the mains. What are they good for? A cheap meter can be a good meter for playing/working on the bench with low power experiments and equipment. There are caveats to this of course. Some cheap meters are really bad garbage meters hiding in sheep's clothing.

"I am only a beginner and I don't see why I need to buy a better meter". Unless you know what to look for then buying a cheap meter could be a bit of a random thing. The really bad part about this is if the argument is that you are just a beginner and you don't need a great meter then you also lack the experience to know if you need a better or safer meter or if the one you are buying is any good at all. This is why if a person isn't sure what they will be doing with their meter then the best thing is to recommend a meter that will keep them safer while they learn and make mistakes.

"OK, so I promise to only use my meter for poking around inside battery operated things or clock radios and the like. So I will go buy that $15 meter I saw on ebay, ok?" Well it might be OK, maybe. If you can't afford to waste money, then you might be throwing away that $15 when/if that cheap meter falls apart in a few months. There is a saying; "Buy quality, buy once. Buy cheap, buy many times." But that is not the only risk to buying a cheap meter. If you are trying to learn and measure things, then the long term stability of the accuracy of the meter comes into question too. Sure, almost any brand new meter regardless of price will probably be within specification out of the box, probably. How will you know? Well if you are a beginner you will be less likely to catch any errors. Do you have any circuits that you are checking that require accurate readings, say something that will blow up if you feed it too high a voltage? That could cost you the price of a good multimeter in one error! If you are trying to learn and you get readings that aren't quite right you aren't going to learn the right things.

Cheap meters will not take a drop as well as a better meter. They might outright break apart or stop working, or worse appear to be work after but not show correct readings. Maybe it will show slightly incorrect readings or worse show no voltage at all when there really is. It is not fun having a live circuit when you think there isn't one.

This is not to say that expensive meters never fail and that all cheap meters are useless. I have a few cheap meters and they have a use in my car, or lying around for easy access to measure the state of some batteries, etc. They are useful to me even with my other expensive multimeters as extra meters for when I need to do multiple measurements at the same time. The ones I have I can cross check with my expensive meters and so I know when something is not right with them.

It is actually ironic. A person who wants a cheap meter to learn or to start out usually is the least qualified to make a good decision on how cheap a meter to buy or whether they should ignore the advice of more experienced people. If you insist on buying a cheap meter, then look for reviews from trusted sources first or discussions on the model you are considering. There are some relatively good cheap meters but they are very few.

For a better understanding of what to be concerned about read the following thread:
https://www.eevblog.com/forum/testgear/a-list-of-multimeters-that-do-not-appear-to-meet-their-claimed-safety-specs/

If you do buy a cheap meter avoid the temptation to use it on higher energy circuits when something comes up "just once".

« Last Edit: July 11, 2013, 07:34:25 pm by Lightages »
 

Offline babysitter

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Re: Cheap multimeters... what is so bad?
« Reply #1 on: July 11, 2013, 07:30:11 pm »
In my opinion, cheap Mutimeters have their place on the workbench if the 3 following tests are positive:

a) bank account is a desert
b) absolutely no dangerous voltage will see it (edited: And no current sources that might turn parts into plasma.)
c) good meters are withhin reach to regularly check against or for the tasks that simply require it. Be it on your workbench, be it on your next neighbour/electronics shop/radio amateur.

Having a few DMM at home and at work, I just recently updated my cheap Decade-old Voltcraft DMM that I almost always carry with me in my backpack to one with a CAT rating to be able to respond to mains voltage emergencies :)

« Last Edit: July 11, 2013, 08:08:16 pm by babysitter »
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Offline Neilm

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Re: Cheap multimeters... what is so bad?
« Reply #2 on: July 11, 2013, 07:47:54 pm »
In my opinion, cheap Mutimeters have their place on the workbench if the 3 following tests are positive:

a) bank account is a desert
b) absolutely no dangerous voltage will see it
c) good meters are withhin reach to regularly check against or for the tasks that simply require it. Be it on your workbench, be it on your next neighbour/electronics shop/radio amateur.

Having a few DMM at home and at work, I just recently updated my cheap Decade-old Voltcraft DMM that I almost always carry with me in my backpack to one with a CAT rating to be able to respond to mains voltage emergencies :)

I have a slight issue with point 2. I have seen several cheap meters when I was doing safety qualification work. One I saw had tested the short circuit current of a large battery bank. The actual voltage was reasonably low (24V from memory). The meter had exploded with quite a nice  fireball. Obviously if the user had connected it to mains it would have been much worse.

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Offline mtdoc

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Re: Cheap multimeters... what is so bad?
« Reply #3 on: July 11, 2013, 08:13:17 pm »


I have a slight issue with point 2. I have seen several cheap meters when I was doing safety qualification work. One I saw had tested the short circuit current of a large battery bank. The actual voltage was reasonably low (24V from memory). The meter had exploded with quite a nice  fireball. Obviously if the user had connected it to mains it would have been much worse.

Neil

This is a good point.  The short circuit current of even a single 12volt auto battery can be very high and dangerous.

If they made a super cheap volt/ohm meter with no current measurement option then you might have something "idiot proof" for use on low voltage/battery circuits.
 

Offline c4757p

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Re: Cheap multimeters... what is so bad?
« Reply #4 on: July 11, 2013, 08:18:33 pm »
Or just a fuse. I've seen a lot of cheap-ass multimeters that don't even fuse the 10A range. Obviously the fuse is eliminated for cost-cutting reasons, but you don't have to cut every cost, only ones that aren't ridiculous to cut. In my book, leaving a range unfused to save money is about as reasonable a cost-cutting measure as making the meter unadjustable and requiring the user to consider calibration factors using a pocket calculator and sticky notes...
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Offline babysitter

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Re: Cheap multimeters... what is so bad?
« Reply #5 on: July 11, 2013, 08:22:39 pm »
@neilm: Accepted and edited.
@mtdoc: I guess Resistance Range is easy to detonate, too.
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Offline Wytnucls

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Re: Cheap multimeters... what is so bad?
« Reply #6 on: July 11, 2013, 09:45:43 pm »
Some of the cheap meters are getting really good these days.
Case in point: the UNI-T UT120C. (~15$) Good built quality and a nice set of features.
I put that meter through some torture tests on the mains (240V) on all ranges, including a massive short on the 400 mA range.
No smoke, no sparks, no excessive heat and everything works normally afterwards, except for the uA/mA range which has lost its auto/manual range function.
The polyswitch was just a tad too slow to block off all of the high current. There is no visible damage on the PCB and its components, but one of the MELF resistors needs to be replaced, as its value has dropped dramatically.
Although the meter seems pretty safe with high voltage and current, there are much sturdier meters out there for the job, with proper CAT ratings and input protection.
This one is great for the toolbox or for the bench for someone on a tight budget.
Here is the full review for those interested: https://www.eevblog.com/forum/testgear/uni-t-ut120c-review-and-tear-down/msg180726/#msg180726
« Last Edit: July 11, 2013, 09:52:53 pm by Wytnucls »
 

Offline jmacqueen

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Re: Cheap multimeters... what is so bad?
« Reply #7 on: July 11, 2013, 09:59:14 pm »
I have always had a couple of cheap meters around, usually analogs. I consider them basically disposable and use them for simple continuity and 12/6 volt reading on automotive or small engine work on the farm..

If I pop a diode inside or they get doused or dropped or whatever it's no big deal. Always have one or usually two laying around my mechanic shop where I work on everything from antique cars/tractors/trucks/motorcycles to chainsaws and mowers and such. My better meters are reserved for more accurate or safety demanding work. Most of my cheapos have been at least good enough to have a fuse, but not all of them.. ;)  Most of them I would not plug in to live mains.
 

Offline Lightages

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Re: Cheap multimeters... what is so bad?
« Reply #8 on: July 11, 2013, 10:50:03 pm »
Of course there are useful cheap meters, I have some as already mentioned. The key is that a beginner knows not to use them anywhere he is not sure of what he is measuring. I would consider the following meters to be good enough for low budgets but not good enough for mains measuring:


https://www.eevblog.com/forum/reviews/uni-t-ut10a-review/

I don't want to recommend any meter that shares a current measurement on the same jack as the voltage/ohms jack. This is asking for a beginner to do harm to his meter, equipment, or himself. Same with a meter that does not have fuses on any of the current measurements.
 

Offline rsjsouza

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Re: Cheap multimeters... what is so bad?
« Reply #9 on: July 11, 2013, 11:57:09 pm »
The main issue I see in item b) of babysitter's post is the human factor: if an appliance stops working for any kind of reason, an enthusiast/beginner person can and probably will grab the nearest (or the only available) DMM in a whim.

Obviously that experienced people may grab a cheap one as well in a momentary lapse of judgment :), but with the difference the reaction would be :palm: instead of  :wtf:

 
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Offline onlooker

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Re: Cheap multimeters... what is so bad?
« Reply #10 on: July 12, 2013, 12:36:51 am »
Every coin has 2 sides.

Electronics as a profession or a hobby or for beginners had been practiced for a long time with higher voltages before the inventions of the CAT ratings and the digital things (e.g. DMM). Can anyone assert there were significant portion of casualties due to these?

The best DMM can't prevent an ignorant decides to probe mains with two fingers.

For many to start with,  a cheap meter is enough to have fun in electronics. Anyway, that was how I started and, yes,  I had used fingers to probe mains when I was around 6 or 7.
« Last Edit: July 12, 2013, 12:46:04 am by onlooker »
 

Offline Rory

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Re: Cheap multimeters... what is so bad?
« Reply #11 on: July 12, 2013, 12:44:29 am »
A quality meter will last many years, some of them more than a lifetime.

Over 20 years ago I bought a brand-new Fluke 97 Scopemeter - on sale for just under $2K USD. That was a lot of money for me but worth every penny. It's been through several sets of batteries, worn out probes and a burned out charger but it still measures within its specifications. It's now in need of a replacement EL backlight but is quite readable without it. Hasn't been babied but does what it was designed to do.  I'd like to get exact replacement probe kit but it's prohibitively expensive and the cheap scope probes work fine with it.  And it's sitting on the bench right now watching the seconds tick on WWV while triggered by a GPS PPS pulse, measuring propagation delay from Colorado to Louisiana, 6.8 mS or so.

I was given a Simpson 260 by a friend who inherited it from his late ham operator father who had bought it in the early 60's with original probes (with insulated alligator clips) and leather flip-around case. Rugged and dependable analog meter that is accurate enough for most purposes outside of the lab. In this case it seriously outlived the original owner, and will probably outlive me in usefulness. It gets a lot of use around the house, from checking breakers on the HVAC unit in the attic to outside with the car. And the batteries seem to last forever.

We have a couple of Fluke 77s at work that have been in constant use for a decade at least, still keep their calibration and just plain work. Even the probes are quality. We've grown to depend on them as a simple, basic DMM that doesn't need a lot of fuss.

On the other hand, like a lot of people I know, I have a couple of those cheapie $10 yellow (plastic) chinese do-it-all meters around the house, cheap leads broken and lost, batteries run down or stolen for a project and basically thrown in the drawer as the junk they are. Usually they came as 'freebies' or a bonus from another purchase. I dropped one once and it basically exploded into pieces.

The point being, you get what you pay for. If you think long term, it works out better (at least for me) to stretch a little and pay the extra money for a decent piece of equipment you know is going to last.

Of course if your stuff lasts a long time you don't need to keep up with the newest and greatest...
« Last Edit: July 12, 2013, 04:21:38 am by Rory »
 

Offline Lightages

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Re: Cheap multimeters... what is so bad?
« Reply #12 on: July 12, 2013, 12:53:17 am »
Electronics as a profession or a hobby or for beginners had been practiced for a long time with higher voltages before the inventions of the CAT ratings and the digital things (e.g. DMM). Can anyone assert there were significant portion of casualties due to these?
I have no information on that. People used to drive around with their kids on the back shelves of the rear window without seat belts, drank and drove, smoked everywhere, etc... Do you really want to argue that we should just all go back to being stupid?

The best DMM can't prevent an ignorant decides to probe mains with two fingers.

You can lead a horse to water but......

For many to start with,  a cheap meter is enough to have fun in electronics. Anyway, that was how I started and, yes,  I had used fingers to probe mains when I was around 6 or 7.

I am glad you survived. I did stupid things to when I was young but I wouldn't do them again.
 

Offline Bored@Work

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Re: Cheap multimeters... what is so bad?
« Reply #13 on: July 12, 2013, 05:28:09 am »
Safety is not negotiable. Period.

You always have some people who think they are invincible and argue they are so special it won't happen to them, never ever. I don't care about this people. If they are going to kill themselves, good riddance. 

But these people have an annoying habit. They affect and endanger others. And that is where I start to care. Despite what all the cheap multimeter fanatics say, they don't have full control over where, when, by whom and why that piece of shit they call a multimeter is used.
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Offline Lightages

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Re: Cheap multimeters... what is so bad?
« Reply #14 on: July 12, 2013, 06:22:13 am »








And this last one, someone was obviously pissed off with the meter not working right.
 

Offline vk6zgo

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Re: Cheap multimeters... what is so bad?
« Reply #15 on: July 12, 2013, 07:25:45 am »
Electronics as a profession or a hobby or for beginners had been practiced for a long time with higher voltages before the inventions of the CAT ratings and the digital things (e.g. DMM). Can anyone assert there were significant portion of casualties due to these?
I have no information on that. People used to drive around with their kids on the back shelves of the rear window without seat belts, drank and drove, smoked everywhere, etc... Do you really want to argue that we should just all go back to being stupid?

I think the point is,that the people who used analog meters were NOT stupid,& mostly had a better idea on safety issues than many today.

For instance,they KNEW that you must not connect a multimeter across the mains when it was switched to a current range or resistance range.
This was not specialist knowledge---even the blokes selling Radio parts over shop counters knew it!

You "have no information " on what the rate of casualties were.-----but that doesn't stop you pontificating about the matter!


The best DMM can't prevent an ignorant decides to probe mains with two fingers.

You can lead a horse to water but......

For many to start with,  a cheap meter is enough to have fun in electronics. Anyway, that was how I started and, yes,  I had used fingers to probe mains when I was around 6 or 7.

I am glad you survived. I did stupid things to when I was young but I wouldn't do them again.

"
So why are some relatively expensive meters pushed on people? Well if you do anything other than poking your meter leads inside battery powered and low power AC connected equipment, then you are beginning to expose yourself to some random hazards. These hazards can be lightning strikes kilometers away causing a surge on the mains, a bad appliance somewhere in your house causing spikes on your wiring, even a faulty transformer on the utility pole outside. In other words you are playing with some potentially very hazardous conditions when you start poking around house wiring and the power distribution box in the house


If all these terrible things are happening all the time,how is it that domestic appliances survive for tens of years in millions of households?
Your chance of hanging your meter across the Mains at the exact instant that a lightning strike/surge/spike occurs is similar to your chances of winning Lotto.

If any time in my 40-odd years working in Electronics-mainly in Radio & TV Transmitting sites,I had said "EEK! I can't measure the Mains,there might be a lightning strike kilometres away!",my Boss would have thought I was crazy!

Yes,by all means buy a good meter,but not so you can do stupid things & get away with it.
Misuse of equipment is mainly due to ignorance---if you know the hazards you will work safely,but making up unlikely scenarios just spoils the safety argument.

My meter at the moment is a Fluke 77---no CAT ratings,but it is properly engineered,& I have measured Mains voltages with it on numerous occasions,as indeed I did with older Fluke & Beckman DMMs,as well as AVO8, Simpson & other analog meters.
 

Online sleemanj

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Re: Cheap multimeters... what is so bad?
« Reply #16 on: July 12, 2013, 07:32:40 am »
The EEVBlog is not really the appropriate forum to get a well rounded opinion on low price multimeter (or low price electronics equipment in general). 

The majority of the people here (at least the frequent posters) are professionals, are trying to become one, or would just like to think they are one.  (NB: I do not fall into any of these categories, I'm a cheap ass lazy disorganised tinkerer who never finishes any project he starts, pretty much the antithesis of a professional.)

It would be like a guy who wants to tinker with his car on the weekend posting in a forum frequented by F1 Pit Team mechanics or Aircraft Engineers "hey what does everybody think of this socket set for $20", which would result in a resounding series of responses not unlike you get here when this sort of topic comes up, "what a heap of crap", "you must be joking! you should buy this $1500 set at a minimum", "those sockets will probably shatter and shoot pieces into your eye if you try torqueing down a 737s engine pylon bolts, dangerous!", "it doesn't even have a socket big enough for an F1 wheel nut!".

Professionals tend to be blinkered to the needs of the common folk, that's fine, you're not common folk, but it would be good if you'd realise that from time to time and say "hey, you know, I'm probably a bit biased here because I'm a pro and so I always work with excellent equipment, I wouldn't personally use that [insert tool], but used within it's limitations, which realistically is probably all you want, it'll be fine".

That's not to say that all cheap meters are fine, the $5 jobs are only worthwhile really to throw in the glovebox or garage drawer - even I have standards, cheap bastard that I am. 
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Offline babysitter

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Re: Cheap multimeters... what is so bad?
« Reply #17 on: July 12, 2013, 09:18:49 am »
Yes, I bought my first DMM as a early teenager on pocket money. Yes, my father, technician at that federal telco in that times told me about the dangers and how to use it. Yes, sometimes I needed to ask him for advice or his I think BBC DMM :)
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Re: Cheap multimeters... what is so bad?
« Reply #18 on: July 12, 2013, 09:58:43 am »
Old analog meters may not have had CAT ratings, but especially the expensive ones were built to much higher standards than any cheap DMM (some might argue any DMM). Clearances were larger. They were also generally not designed for handheld use, making the issue of exploding/melting much less dangerous. So no, you can't just compare today's $15 meter with the old AVO and Simpson meters.
 

Offline Chalky

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Cheap multimeters... what is so bad?
« Reply #19 on: July 12, 2013, 10:07:52 am »
What do you not get in a cheap meter?  Accuracy.  I'm a hobbyist, and a cheap meter is fine for me.  I'm repairing Elmo toys, testing continuity, measuring batter voltages, etc.  Cheapest meter you can find is fine for that stuff.  And don't want to measure mains, I already know it's 230 VAC, and since my TV's working, I can assume the mains is just fine.  I only own a more expensive meter now because I can afford it, and it's some sort of weird psychological hobby self-justification! 
 

Offline EEVblog

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Re: Cheap multimeters... what is so bad?
« Reply #20 on: July 12, 2013, 10:50:08 am »
The EEVBlog is not really the appropriate forum to get a well rounded opinion on low price multimeter (or low price electronics equipment in general). 

That's because you don't need an opinion on a cheap-arse meter. If that's what you want then you pay your ten bucks and be happy with whatever crap meets the price.
 

Offline vk6zgo

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Re: Cheap multimeters... what is so bad?
« Reply #21 on: July 12, 2013, 12:10:25 pm »
Old analog meters may not have had CAT ratings, but especially the expensive ones were built to much higher standards than any cheap DMM (some might argue any DMM). Clearances were larger. They were also generally not designed for handheld use, making the issue of exploding/melting much less dangerous. So no, you can't just compare today's $15 meter with the old AVO and Simpson meters.

Apart from that,the issue of exploding/melting was less dangerous,because the likelihood of it happening was vanishingly small.
I never heard of any of the little Sanwa El Cheapo analogs exploding,although there were thousands of them around!

Early DMMs like the Beckman didn't explode or melt,either!

It is not good practice to handhold a meter when measuring Mains if you can help it,just in case you are silly enough to leave it on a current or resistance range.

Interestingly,both the meters blown up in Lightage's videos were sitting there propped up on their bale arm in the correct manner.
There is no indication in either video as to what range they were set to.
Has anyone a video of a DMM blowing up when set to the correct range to read 240V AC?

All that said,newbies these days do seem to have a fixation with Mains supplies.
Perhaps the danger is in letting people who know nothing, & don't really want to learn, loose on mains voltages.

 ;D
 

Offline Lightages

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Re: Cheap multimeters... what is so bad?
« Reply #22 on: July 12, 2013, 03:09:06 pm »
Of course the most likely dangerous failure of a multimeter is going to happen from improper use. Who is most likely to misuse a multimeter? A beginner of course. My examples of the types of faults outside of this were just a couple that came to mind.

So forget the safety issue. It is not a worry with the measurements you are going to make. A cheap meter is not going to be reliable just like any other cheap item. The difference is that you are making other decisions based on the readings of a cheap meter.

Quote
The EEVBlog is not really the appropriate forum to get a well rounded opinion on low price multimeter (or low price electronics equipment in general)

I provided two reviews on low priced multimeters that aren't junk. I don't think you can get anything lower in price that you can count on. I could be wrong.
 

Offline Neilm

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Re: Cheap multimeters... what is so bad?
« Reply #23 on: July 12, 2013, 05:19:47 pm »

Early DMMs like the Beckman didn't explode or melt,either!


They weren't built to the lowest price.

Quote

It is not good practice to handhold a meter when measuring Mains if you can help it,just in case you are silly enough to leave it on a current or resistance range.

Interestingly,both the meters blown up in Lightage's videos were sitting there propped up on their bale arm in the correct manner.
There is no indication in either video as to what range they were set to.
Has anyone a video of a DMM blowing up when set to the correct range to read 240V AC?

All that said,newbies these days do seem to have a fixation with Mains supplies.
Perhaps the danger is in letting people who know nothing, & don't really want to learn, loose on mains voltages.
Of course they were set up - no one I know would want to hold them while they explode like that. When I did these sorts of tests, we had the test item in a separate room and remotely energised it. I would note that I have seen a video with a dummy holding the test leads and the meter stood up on the side.

When the connection was made, the meter exploded and the voltage rise as the short cleared caused a secondary arc flash between the probes. The dummy caught fire. This was based on an actual accident - the worker who took the role of the dummy had 3rd degree burns from the waist up.

IEC 61010 states the manufacturer should test for forseeable misuse - connecting to a rated supply with the meter in current mode rather than voltage mode is forseeable.

Neil
« Last Edit: July 12, 2013, 05:21:40 pm by Neilm »
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Offline rsjsouza

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Re: Cheap multimeters... what is so bad?
« Reply #24 on: July 12, 2013, 07:19:57 pm »
Of course the most likely dangerous failure of a multimeter is going to happen from improper use. Who is most likely to misuse a multimeter? A beginner of course.

Or a tired/overly confident expert. :)

The EEVBlog is not really the appropriate forum to get a well rounded opinion on low price multimeter (or low price electronics equipment in general)

Anything read on the internet cannot be taken face value. If someone comes to this forum asking for suggestions, that is what they will get, but ultimately the purchasing decision is theirs. That said, since I discovered this forum 1-1/2 years ago I find the criticisms are becoming much more subdued towards el-cheapo DMMs, with the obvious remarks of safety (Lightages reviews are a good example of that).

It would be like a guy who wants to tinker with his car on the weekend posting in a forum frequented by F1 Pit Team mechanics or Aircraft Engineers
As an anecdotal evidence, in the past I had cuts and bruises with tools that broke on my hand due to the quality of the material and I am not a tool professional or expert, thus my reaction was  :wtf:, while a professional would simply  :palm:

"hey, you know, I'm probably a bit biased here because I'm a pro and so I always work with excellent equipment, I wouldn't personally use that [insert tool], but used within it's limitations, which realistically is probably all you want, it'll be fine".

I like that, but with a few modifications: "Hey, you know, I'm probably a bit biased here because I'm a pro and so I have seen or heard horrible stories and experienced some bad scenarios that convinced me that I wouldn't personally use that [insert tool], but if you are really sure you will use within it's limitations, which realistically is probably all you want, don't underestimate that accidents usually happen under stress, tiredness or distraction and this will not be fine."

All that said, I still think the human factor is what counts the most, and alm/vk6zgo remarks about old meters are good examples. In the past such equipment was so expensive that people would naturally be more cautious when using one - and I am not only talking about professionals, but hobbyists like me where a DMM was worth its weight in gold. I grew up using my dad's ICE supertester 680R that would be laughable by today's standards, but the bastard was so expensive we couldn't afford making mistakes!

Has anyone a video of a DMM blowing up when set to the correct range to read 240V AC?

I've seen sparks, sounds and "ampères' smell" when the meter is set to an unfused 10A input and plugged directly to mains.

« Last Edit: July 12, 2013, 09:38:54 pm by rsjsouza »
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Offline vk6zgo

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Re: Cheap multimeters... what is so bad?
« Reply #25 on: July 13, 2013, 02:57:52 am »

Early DMMs like the Beckman didn't explode or melt,either!


They weren't built to the lowest price.
I also said "I never heard of any of the little Sanwa El Cheapo analogs exploding,although there were thousands of them around!
These "pocket" Sanwas were definitely built down to a price,& were the instrument of choice for many hobbyists.

Quote

It is not good practice to handhold a meter when measuring Mains if you can help it,just in case you are silly enough to leave it on a current or resistance range.

Interestingly,both the meters blown up in Lightage's videos were sitting there propped up on their bale arm in the correct manner.
There is no indication in either video as to what range they were set to.
Has anyone a video of a DMM blowing up when set to the correct range to read 240V AC?

All that said,newbies these days do seem to have a fixation with Mains supplies.
Perhaps the danger is in letting people who know nothing, & don't really want to learn, loose on mains voltages.
Of course they were set up - no one I know would want to hold them while they explode like that.
You've misunderstood me.
I said that standing a DMM up on its bale arm instead of holding it is the correct method when measuring the Mains!


When I did these sorts of tests, we had the test item in a separate room and remotely energised it. I would note that I have seen a video with a dummy holding the test leads and the meter stood up on the side.

When the connection was made, the meter exploded and the voltage rise as the short cleared caused a secondary arc flash between the probes. The dummy caught fire. This was based on an actual accident - the worker who took the role of the dummy had 3rd degree burns from the waist up.

IEC 61010 states the manufacturer should test for forseeable misuse - connecting to a rated supply with the meter in current mode rather than voltage mode is forseeable.

Neil
 

Offline Robomeds

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Re: Cheap multimeters... what is so bad?
« Reply #26 on: July 13, 2013, 03:49:06 am »
I think cheap meters can be a good value and I have recommended them to others but with specific caveats.  Not long ago one of my sibs was asking about testing a small heating device (don't remember the details but probably 200W, AC powered).  It had quit working and he needed something to do basic continuity checks.  I told him the cheap Harbor Freight meters (830B meter) would be sufficient for that task.  I also told him to never use it on anything more than a 110 wall outlet and it would probably be best to never even use it on that.  He's smart enough to understand that a wall outlet can dump a lot more power than a battery toy.  In the case of what he was looking at the circuit was dead when he was testing it.  We decided the thermal fuse had blown.  That was enough to decide not to repair the thing.  Meter did it's job.

Basically the 830Bs are a cheap and junky as the meters get.  My take is those are OK as "emergency", low power tools.  The sort of thing that might help you find a short or open circuit from time to time.  When I was younger and working with RC cars even an 830B would have served my needs.  I actually used a pocket Radio Shack meter for about a decade with no issues.  Nothing fancy but even perhaps 2 decades later it agrees with my Fluke 87 with in the meter's tolerance (1.3222 vs 1.323).  Many of the cheap meters have lose tolerance ranges but I've rarely run into one that didn't hit the specs unless it was really messed up. 

The build quality can be an issue.  I think some of the junk meters can last a long time if you treat them well.  They will also die a quick death if you use them every day and with little care. 

I certainly see the differences in safety.  I would feel safe working on basically any 12V circuit in say a car with a meter with even cheap fuses so long as all inputs are fused.  A 12V battery has plenty of amp potential but I just don't see a 500V or 5000V spike coming out of my car battery.  So long as the voltage can't be high why worry about a better than glass fuse?

If someone talks about measuring things in their house wiring I will tell them to get a decent meter or as often as not, don't touch it.

All that said, I really do appreciate a good meter.  Many of the little differences do add up and I got a deal of a Fluke.  I don't think it has done much I couldn't have done with cheaper meters but I sure do like using it!
 

Offline don.r

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Re: Cheap multimeters... what is so bad?
« Reply #27 on: July 13, 2013, 04:04:41 pm »
Its all about confidence. Confidence in safety, confidence in accuracy, confidence over time. How much you are willing to pay for this confidence is an individual decision. Personally, I think the UT136B is the "best" meter under $25. I have confidence that the meter will give me decent readings in a safe manner. I wouldn't go measuring any high voltage circuits with it, however. I'm not so confident about the probes that came with the meter either.
 

Offline Spunky

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Re: Cheap multimeters... what is so bad?
« Reply #28 on: July 15, 2013, 12:27:56 am »
Interesting thread. I have cheap meters, and good ones. I use them each for what they're good for. Cat4 meters (Fluke, Metrel, etc) with fused leads for electrical installations, but then I've been using a chinese VC99 today for repairs on PCBs. It's fine for that, and perfectly safe on an isolated ELV circuit or for automotive work. It's actually nice to use, it has all the ranges I need and nice big digits.

You should see what my dad used to have as a mains tester, a light bulb with 2 wires soldered to it. Now that's not recommended  ;)
 

Offline Phaedrus

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Re: Cheap multimeters... what is so bad?
« Reply #29 on: July 15, 2013, 03:53:50 pm »
Harbor Freight 830B at home, Fluke 85 V at the lab. At home I rarely do anything higher-voltage than measuring 18650s for charge. In the lab I work on prototype power supplies that may or may not contain faults that could cause a sudden voltage spike or other dangerous situation. Or at the old lab when I needed to occasionally check the 400V 3-phase for faults because our AC source was hiccuping.

Although to be honest I'm more worried about the PSUs themselves killing me than the meter. Ever seen a pair of 420V 480uF electrolytic caps blow up? I have. And smelled it. Those were Rubycons too! :wtf:


Anyway, the point is that a cheap meter is fine for low-voltage applications, but if you're going to be working with high voltage or any type of unpredictable system, I highly recommend a quality meter.
« Last Edit: July 15, 2013, 06:16:25 pm by Phaedrus »
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Offline mzacharias

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Re: Cheap multimeters... what is so bad?
« Reply #30 on: July 15, 2013, 06:15:34 pm »
Harbor Freight 830B at home, Fluke 85 V at the lab.

If you really have an "85-V" I'd give you some serious money for it.

Guessing you meant "87V" ? The 85's didn't make it past the III series.
 

Offline Phaedrus

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Re: Cheap multimeters... what is so bad?
« Reply #31 on: July 15, 2013, 06:24:01 pm »
Prolly misread it, I'll check it next time I'm at the lab. I didn't spec any of this equipment, this was all picked out by the previous engineers. So I don't really remember the part #s.
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Offline mzacharias

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Re: Cheap multimeters... what is so bad?
« Reply #32 on: July 15, 2013, 06:44:20 pm »
No need. I was just yanking you around. Couldn't help myself. But yeah - they go straight from 83 to 87 in the "V" series.

Have a great day!

 :-+
 

Offline Phaedrus

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Re: Cheap multimeters... what is so bad?
« Reply #33 on: July 15, 2013, 06:57:30 pm »
Well now I want to know what's actually on my bench, so... :p


But yeah, I would not test a 400V 3-phase line with anything less than a Fluke or similar quality instrument with full safety ratings. I would not trust the Harbor Freight with my life in that instance. It might work. But it might not. I *know* the Fluke will work.
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Offline elliott

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Re: Cheap multimeters... what is so bad?
« Reply #34 on: July 15, 2013, 10:15:50 pm »
I always keep a few of the Harbor Freight meters on hand, every once in a while they have a coupon for a free one with any purchase. You could buy a candy bar and get a multimeter. I've actually wondered if it is worth the cost of replacing the batteries in them when I forget and leave them on.

Since both of my bench power supplies have analog meters, I keep a Harbor Freight meter connected to each one for a voltage measurement. Of course, I always verify the readings against a good meter before I start using one.

My main meters don't get much love on here either though, Extech EX530s, I bought one a few years ago and it has been a great meter. I started having problems with the main input jack though and Extech just sent me another one under warranty, told me to just dispose of the other one. Of course, I kept it and use it for current measurements only now since those jacks are just fine. The main jack is just a little oversized from years of use and various leads of questionable quality, I could probably fix it if I removed the plastic around it and just crimped it down a little. They molded the jacks into that model for water proofing, so there is no way to actually replace them.
 

Offline Phaedrus

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Re: Cheap multimeters... what is so bad?
« Reply #35 on: July 15, 2013, 10:51:08 pm »
Speaking of Extech, our Extech 380820 just bit the dust an hour ago after the power supply we were testing failed (internal short between +12V and ground). The power analyzer appears totally dead. We checked the fuse and it's fine. Something in the analyzer has failed internally. Joy.
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Offline marshallh

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Re: Cheap multimeters... what is so bad?
« Reply #36 on: July 16, 2013, 04:11:44 am »
Put a new 9v into my cheapo Velleman DVM830L (rebranded under many other names)



I had the back open so I felt the chunk blow out. Didn't reverse battery polarity, it showed properply for about 5 seconds, then showed low battery and then POP.


Good thing I have a Fluke 87 now.
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Offline Lightages

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Re: Cheap multimeters... what is so bad?
« Reply #37 on: July 16, 2013, 05:30:12 am »
Thanks for that image marshallh. It shows that it is not just safety we are talking about, it is reliability and measurement confidence too.
 

Offline rsjsouza

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Re: Cheap multimeters... what is so bad?
« Reply #38 on: July 16, 2013, 04:13:46 pm »
Put a new 9v into my cheapo Velleman DVM830L (rebranded under many other names)
Maybe that explains the catastrophic failure: according to Velleman's webpage, this DMM is powered by two AAAs...  :-DD

(yeah, I know there are zillions of hardware revisions... Just pulling your leg)
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winluk

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Cheap multimeters... what is so bad?
« Reply #39 on: July 16, 2013, 04:48:18 pm »
Have you divided by zero by any chance? :)
 


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