Fluke 17B+ / RMS

[Electro Fan]

I know there have been a ton of threads on DMMs but I'm homing in on purchasing a 17B+ for a college student.  It's reasonably priced, compact, a Fluke, and generally seems to have good functions and ok specs. The one thing I'm not too sure about though is that it seems to do RMS "averaging" vs. "true" RMS.   

This link is for the 17B (not the 17B+); under Basic features it says "True-rms readings Avg AC" ??
http://www.mantech.co.za/Datasheets/Products/FLUKE%2015B-17B.pdf

This link is for the 17B+; it doesn't reference rms at all ??
http://www.kipia.info/upload/DOCU_PDF_RAZN/Fluke_doc/Fluke15B_Plus.PDF

Any thoughts on the significance and practical results of true-rms vs avg rms? 

I fully get that a non-RMS DMM will read 5.5 volts AC where a true-RMS DMM will read 5.0 volts AC (with a 5 volt AC source), but I'm trying to understand why Fluke would list the 17B as "True-rms readings Avg AC" (and also why Fluke's spec sheet for the 17B+ doesn't reference rms at all).

Thanks for any help/clarifications.

[Fsck]

can I just suggest the bm257 as an alternative? it even has a logging option which is a handy function to have. google says they should be around the same price range (without logging kit)

personally, I don't find myself doing ac measurements often. I actually don't remember the last time I had to do one, but I don't pay attention to such details.

I believe the true-rms box means whether or not the meter is true-rms or average ac, and in this case the meter is only averaging.
I suspect that in the B version, they recognized the confusion from the above statement in the datasheet and simply omitted it so it's probably just averaging.

[Lightages]

The 17B+ is not TRMS. It is still a pretty good meter and built very well. As has already been said, the BM257s has some more features and is TRMS, AC only..

[Electro Fan]

I appreciate all the enthusiasm for Brymen - there are may Brymen fans here, no doubt - but I'm really more interested for this particular situation to go with the Fluke. 

What I'm trying to understand is what is the practical limitation or disadvantage of "average rms"  vs "true rms", and why would Fluke list the 17B with a row header that says "True-rms" and then across from the row header list "Avg AC"?  And why does Fluke not cite the same wording/terminology on the spec sheet for the 17B+?  Perhaps it is as Fsck says, Fluke decided it was confusing - so maybe the 17B+, like the 17B does averaging rms - in which case I'm just down to figuring out what the practical limitation of averaging rms will be vs. true rms.  For example, on an AC signal that reads 5 volts on a True rms DMM and 5.5 volts on a non rms DMM, what would it read on an averaging rms DMM?

Thanks again for any help with these questions.

[Muxr]

Normal averaging works just as well as True RMS if you're dealing with your standard sinusoidal AC signals. Where True RMS gives you an advantage is if you're trying to measure non sinusoidal signals, square wave for instance.

However many True RMS meters are AC coupled so they can't deal well with DC offsets in AC measurement mode. So it's another thing to watch out for.

w2aew does a really nice explanation in this video:

[Electro Fan]

Normal averaging works just as well as True RMS if you're dealing with your standard sinusoidal AC signals. Where True RMS gives you an advantage is if you're trying to measure non sinusoidal signals.

However many True RMS meters are AC coupled so they can't deal well with DC offsets. So it's another thing to watch out for.

w2aew does a really nice explanation in this video:

Ok, that's very helpful.  So, is a standard U.S. 120V AC signal likely to be sinusoidal (seems like the answer is yes).  So now we're down to use cases where the AC signal is something else - in which case the reading could be off by 10% (or more?)?  And then to your point, even if a meter is True-rms it still might not get the reading right if there is a DC offset, so True-rms alone doesn't assure an accurate AC reading.  An accurate reading would require AC + DC rms (or is that AC-rms + DC-rms?), correct.  So when a meter is listed as AC and DC rms that doesn't mean there is an application for DC rms by itself (because any DMM meter can figure out the DC level), what AC+DC rms means is that the meter will calculate a non-sinusoidal AC signal value correctly and it will do so while factoring in a DC offset. 

So.... for most common uses (like checking wall voltage) an AC rms avg DMM will do the job; the next step up would be true AC rms, and the cat's meow would be a AC+DC rms DMM.  Yes?

Thanks

[Muxr]

You got it!

[Electro Fan]

Thanks Muxr, but I have a few more questions

At about 1:40 in the video w2aew (who is consistently magnificent with his videos) says that the average of his pure sine wave is simply 0, which is not the same as the rms value.

What I think all this means - please correct me if I have it wrong - is that a true rms AC DMM calculation must somehow calculate the shape of the signal (probably via sampling) and then determine the value.  So even if the waveform is not a pure sinewave the DMM will calculate the correct value described by the waveform.  This will result in the right answer as long as there is no DC offset, but if there is a DC offset this "true rms AC" DMM will arrive at the wrong value.

Next (as per the point made at 1:40 in the video), if a meter labeled as an "Average rms AC" DMM computes the value of a true sinusoidal waveform it will get the right value - but NOT because it calculated an AVERAGE value.  It will get the right value only because it simply calculates the peak (or (peak to peak)/2?) value and then applies the .707 multiplier.  If this is correct, while it is called "average AC rms" it is not really computing the average value of the waveform, rather it is assuming that the waveform is an "average" (ie, "typical") sinusoidal waveform which allows it to get the right answer with less sampling and calculating sophistication than a true rms AC DMM.

Next, we have the non-rms DMM which for some reason is so brain dead (probably to save a few logic gates and therefore a few $) that it just measures the peak value for AC and doesn't even have the ability to multiply by .707.  Hard to believe this saves enough money to warrant leaving it out, but I guess these products exist because designers (and marketers) have decided that if they include it and call it an "average" AC rms DMM then people might expect an accurate result on AC (because they saw "rms" on the label) and then later become disappointed (if measuring a non pure sinusoidal AC signal).  So both to save a few $ and also to avoid disappointment DMM manufacturers generally don't offer "average' AC rms.  In the case of Fluke, they figured they had every other combination offered so they should serve the market for "average rms AC" with the 17B but they got tired of addressing all these questions and just left it out of the 17B+ literature (but presumably left it in the 17B+ product - which is just a guess since it's not confirmed anywhere?).

Finally, as mentioned earlier, for excellent results in all situations a true AC+DC rms meter is required, which interestingly is not something included even in the highly regarded (by some/many) Fluke 87V.

Yes, No?  Thanks again

PS, if these understandings are not correct please let me know.  On the other hand, if these understandings are correct I guess I'm inclined to still go with the 17B+ as a gift but the better understanding of these distinctions might have taken just a bit off the 87V's rose bloom; I might have to wait for the 87VI to see if it offers true AC+DC rms

PSS, is there anyone out there with a Fluke 17B+ who can measure a pure AC sinewave and determine if the 17B+ gets the same answer as a known good true RMS DMM?

[Muxr]

Thanks Muxr, but I have a few more questions

At about 1:40 in the video w2aew (who is consistently magnificent with his videos) says that the average of his pure sine wave is simply 0, which is not the same as the rms value.

What I think all this means - please correct me if I have it wrong - is that a true rms AC DMM calculation must somehow calculate the shape of the signal (probably via sampling) and then determine the value.

So even if the waveform is not a pure sinewave the DMM will calculate the correct value described by the waveform.  This will result in the right answer as long as there is no DC offset, but if there is a DC offset this "true rms AC" DMM will arrive at the wrong value.

Wikipedia describes three different analog methods on how True RMS measurements are accomplished:

an analog multiplier in a specific configuration which multiplies the input signal by itself (squares it), averages the result with a capacitor, and then calculates the square root of the value (via a multiplier/squarer circuit in the feedback loop of an operational amplifier), or

a full-wave precision rectifier circuit to create the absolute value of the input signal, which is fed into an operational amplifier arranged to give an exponential transfer function, then doubled in voltage and fed to a log amplifier as a means of deriving the square-law transfer function, before time-averaging and calculating the square root of the voltage, similar to above, or

a field-effect transistor may be used to directly create the square-law transfer function, before time-averaging.

I think one of these is probably how your typical DMM does the calculation/sampling.

Next (as per the point made at 1:40 in the video), if a meter labeled as an "Average rms AC" DMM computes the value of a true sinusoidal waveform it will get the right value - but NOT because it calculated an AVERAGE value.  It will get the right value only because it simply calculates the peak (or (peak to peak)/2?) value and then applies the .707 multiplier.  If this is correct, while it is called "average AC rms" it is not really computing the average value of the waveform, rather it is assuming that the waveform is an "average" (ie, "typical") sinusoidal waveform which allows it to get the right answer with less sampling and calculating sophistication than a true rms AC DMM.

Correct it's assuming the sinusoidal waveform hence why it's applying the .707 multiplier. Different waveforms would have different formulas, "Non true average RMS" just assumes the signal is a sine wave. Here are the formulas for other common waveforms:

But since DMMs can't detect which type of waveform is used, you're stuck with the measurement only being applicable to sine waves.

Next, we have the non-rms DMM which for some reason is so brain dead (probably to save a few logic gates and therefore a few $) that it just measures the peak value for AC and doesn't even have the ability to multiply by .707.  Hard to believe this saves enough money to warrant leaving it out, but I guess these products exist because designers (and marketers) have decided that if they include it and call it an "average" AC rms DMM then people might expect an accurate result on AC (because they saw "rms" on the label) and then later become disappointed (if measuring a non pure sinusoidal AC signal).  So both to save a few $ and also to avoid disappointment DMM manufacturers generally don't offer "average' AC rms.  In the case of Fluke, they figured they had every other combination offered so they should serve the market for "average rms AC" with the 17B but they got tired of addressing all these questions and just left it out of the 17B+ literature (but presumably left it in the 17B+ product - which is just a guess since it's not confirmed anywhere?).

My guess is that 17B+ has RMS averaging (using the .707 method above). I have a few Fluke non true RMS meters, 27II and the 83V and they all behave consistent with the method of [non-true] RMS averaging. I've tested this using a signal generator.

Finally, as mentioned earlier, for excellent results in all situations a true AC+DC rms meter is required, which interestingly is not something included even in the highly regarded (by some/many) Fluke 87V.

Yes, No?  Thanks again

This is correct. However even with the Fluke 87V you can measure AC+DC. You just have to measure the components separately and use the following formula to derive your AC+DC value.

Fluke 87V specifically includes a low pass filter to help you make low frequency AC  measurements.

Fluke has an article on this: http://www.fluke.com/fluke/uses/comunidad/fluke-news-plus/articlecategories/electrical/true-rmsfacts

PS, if these understandings are not correct please let me know.  On the other hand, if these understandings are correct I guess I'm inclined to still go with the 17B+ as a gift but the better understanding of these distinctions might have taken just a bit off the 87V's rose bloom; I might have to wait for the 87VI to see if it offers true AC+DC rms

I think you got it.

[Electro Fan]

Thanks again Muxr,

So even the 87III uses/used the (non-true rms) averaging method?  I guess when the 87III was introduced it just cost-too much do add semiconductors that could do true-RMS?

Maybe the same or similar method used in the 87III is used in the 17B+?

What do you think, does it make sense to get a student a an averaging RMS Fluke, or should I cave to the Brymen camp?   I love my Fluke 179

Thanks again, EF

[Muxr]

Thanks again Muxr,

So even the 87III uses/used the (non-true rms) averaging method?  I guess when the 87III was introduced it just cost-too much do add semiconductors that could do true-RMS?

Maybe the same or similar method used in the 87III is used in the 17B+?

What do you think, does make sense to get a student a an averaging RMS Fluke, should I or cave to the Brymen camp?   I love my Fluke 179

Thanks again, EF

Fluke makes non-True RMS higher end meters for some reason. I just don't know what that is. For instance I find a lot of the ex military sales of meters on ebay tend to be non true RMS (it's what my 27II is, military issue). I think there is something military measures that requires it. Perhaps only to be consistent with military procedures written for RMS averaging or something.. but I have no clue.

It's a tough call on which one to get. I haven't used a 17B+ to say with certainty. But I trust a Fluke. If I was going to get a Brymen it would perhaps be the BM257s. Because the price is right and I think it's one of the better meters they make.

The biggest thing that turns me off from 17B+ is the lack of the bar graph. I find the bar graph pretty useful in electronics. Let's you notice flutter, and can give you an insight in what you're looking at beyond what just the numbers tell you.

I don't find the True RMS, non-True RMS to be a big drawback, as long as you know the limitations. I use my 83V and my 87Vs interchangeably on a day to day basis and I don't feel restricted by the lack of True RMS at all.

edit: Yes I am pretty sure 17B+ has a [non true] RMS averaging. I just checked my little 101. And if they bothered to implement it on their cheapest meter don't think they would skimp on the 17B+ and put a non RMS averaging in.

[PedroDaGr8]

Thanks again Muxr,

So even the 87III uses/used the (non-true rms) averaging method?  I guess when the 87III was introduced it just cost-too much do add semiconductors that could do true-RMS?

Maybe the same or similar method used in the 87III is used in the 17B+?

What do you think, does it make sense to get a student a an averaging RMS Fluke, or should I cave to the Brymen camp?   I love my Fluke 179

Thanks again, EF

Just a quick note. He said 83V, not 87III. Every version of the 87 has had True RMS

[Muxr]

Oh right, good catch, didn't notice that. Yes 87s have always had true RMS. Their cheaper 83 cousins didn't have it.

[Electro Fan]

Thanks again Muxr,

So even the 87III uses/used the (non-true rms) averaging method?  I guess when the 87III was introduced it just cost-too much do add semiconductors that could do true-RMS?

Maybe the same or similar method used in the 87III is used in the 17B+?

What do you think, does it make sense to get a student a an averaging RMS Fluke, or should I cave to the Brymen camp?   I love my Fluke 179

Thanks again, EF

Just a quick note. He said 83V, not 87III. Every version of the 87 has had True RMS

Thanks for spotting that and mentioning it.

[Electro Fan]

Ok, after all that it's a thinker.  17B+, or maybe a Fluke 115...?
(And I can see why the Brymen 257s has found a good price/feature niche)

[BravoV]

Finally, as mentioned earlier, for excellent results in all situations a true AC+DC rms meter is required, which interestingly is not something included even in the highly regarded (by some/many) Fluke 87V.

Yes, No?  Thanks again

Yep, for TRMS AC + DC and displaying "both" at the same time, only at 287/289 series if we're talking only Fluke brand.

[Muxr]

Fluke really makes it hard in that price category. 115 doesn't have uA, and 17B+ doesn't have a bar graph. 17B+ doesn't have true RMS, but 115 doesn't have temperature. All of these are useful features. They really make it hard to chose.

Really for a meter over $100 you'd expect the full gambit of the essential features.

Brymen BM257 would cover all these features. I like Fluke but I think I would pick the Brymen in this price bracket honestly. Normally I would suggest perhaps a good Fluke used deal on Ebay, but you're buying a gift, so perhaps Brymen is a good option.

[Lightages]

@electrofan

I would like to know why you a fixed on the Fluke 17B+?

There are many option for good meters with TRMS at lower and slightly higher prices. If you are open to other brands then:

Uni-Trend UT139C $50 with TRMS
Amprobe AM-270 $115 with TRMS and higher accuracy

Just some other options.

[oldway]

RMS measurements are especially important for current.
Indeed, the heating of the electrical conductors and windings of the transformers is dependent of the RMS current value.

In electricity, we generally work with sinusoidal voltages but the currents are often non-sinusoidal.

It is recommended never to use the "current inputs" of a multimeter in a high voltage circuit and high power circuit.
Use a current probe, a transducer, a current transformer or a shunt.

In electronics, the simple measure of the rms value of a current or voltage is not enough, you also have to know the waveform.
Then you must use an oscilloscope.

For all these reasons, the right choice is, in my opinion, regardless a true RMS or not multimeter  + a true rms current clamp.
The current clamp MUST BE TRUE RMS

[Lightages]

In the case stated by oldaway, TRMS AC only is not enough. If you need to now real TRMS you need AC+DC measurement.

[BravoV]

RMS measurements are especially important for current.
Indeed, the heating of the electrical conductors and windings of the transformers is dependent of the RMS current value.

In electricity, we generally work with sinusoidal voltages but the currents are often non-sinusoidal.

It is recommended never to use the "current inputs" of a multimeter in a high voltage circuit and high power circuit.
Use a current probe, a transducer, a current transformer or a shunt.

In electronics, the simple measure of the rms value of a current or voltage is not enough, you also have to know the waveform.
Then you must use an oscilloscope.

... and, when it comes to work with mains and probing it's voltage n current with a scope, an isolated scope is a must and it's expensive accessories like special isolated probe, current probe and etc, which is at the end, the price league is now way beyond an ordinary cheap bench top scope anymore. 

... damn, this never end isn't it ? 

[oldway]

For power electronics, you need an AC + DC rms current clamp with output for oscilloscope.
(For safety, current clamp only, without voltage and resistance measurements...I used such a Metrix current clamp, but I don't remember the model )

EDIT: it was an Itt Métrix MX 1200s...

The best option is , for example, a Fluke i410 ac+dc current clamp + a True rms multimeter.
I have an old Fluke 80i-410 ac + dc current probe, but it has a serious shortcoming: it has no offset adjust.

... and, when it comes to work with mains and probing it's voltage n current with a scope, an isolated scope is a must and it's expensive accessories like special isolated probe, current probe and etc, which is at the end, the price league is now way beyond an ordinary cheap bench top scope anymore. 

  You can choose a cheaper solution: use an isolation transformer to probe mains voltage (is generaly sinusoidal) and ac or ac+dc clamp with output for oscilloscope to probe mains current.

[Electro Fan]

@electrofan

I would like to know why you a fixed on the Fluke 17B+?

There are many option for good meters with TRMS at lower and slightly higher prices. If you are open to other brands then:

Uni-Trend UT139C $50 with TRMS
Amprobe AM-270 $115 with TRMS and higher accuracy

Just some other options.

I wouldn't say I'm fixed on the 17B+ but what I like about the it is that except for true-RMS it has almost everything I am looking for in a DMM.  It would also be nice to have the bar graph and better specs (higher count, more resolution, better accuracy), but except for the lack of true-RMS (for AC) I could live with the the features and specs.  I like the fact that it's somewhat compact and I definitely like the fact that it is a Fluke.

I've had a Fluke 179 for about 10 years and it is rock solid durable, a joy to use, and I trust the readings (I've measured it against other DMMs and standards and I'm very confident in it).  It would be nice if it was tad more compact but that's a relatively small issue.

I've purchased other DMMs and I think I've read the reviews on almost every popular meter mentioned on EEV.  I had (still have) an Amprobe.  On paper it was a great meter, in reality the display was/is almost unusable.  What I've found with not only DMMs but test equipment and almost any category of product is that when you try to save money you can occasionally do so, but too often you wind up spending more because when products don't meet expectations you can sometimes wind up buying twice.  I'm sure Amprobe and UniT and especially Brymen make some A-OK products but without being able to experience them in person it's hard to know what you are really going to get until you open the box; if you could try products before buying them or return them for a refund it would be easier to take a chance on products that offer more value (more features and/or performance for a lower price), but saving 10-20% is only good if the product satisfies you, otherwise you might end up spending 80-90% extra.  Sure you can tough it out and accept the lesser product if it doesn't meet your expectations but why do that with products that you might keep for 5-10 years or longer?

Net, net:  I've come to trust Fluke.  At $50 or so I'm guessing that the UniT 139C or maybe one of their other models is a best choice, and in the $100-150 range my best guess is that the Brymen 257s could be the winner, but for about the same I'm starting to think the Fluke 115 is probably what I'm looking for.  I don't like the fact that the knob on the 11X series isn't recessed (but I generally don't lay my 179 face down) and I could find some other nits about the 115 too.  For example, it doesn't have mA setting, however it will show milliamps in the 0.001 format.  I think for a gift for a student it might almost be desirable to focus more on milliamps and millivolts in learning Ohm's law as opposed to thinking about microamps and having to think about replugging to avoid fuse blows.  Long story short, long after the satisfaction of having saved $15 is the satisfaction or dissatisfaction of using a product for years - so Fluke is my first choice until I discover something better. 

Again, I'm not saying other DMM manufacturers don't make some good products but in my experience Fluke has gained my trust where some others haven't.  If I could try before buying it would be easier to get me to switch.

Just some thoughts.  EF   

[Muxr]

I can definitely understand it. If this is going to be someone's only meter I'd go with a 17B+ then. If it's a second meter then I would go with a 115, since you can use the uA and temp measurements on another meter.

edit: bah, I don't know. The bargraph is really useful. And uA just increases the chance they will blow the fuse while learning. Temp is handy but a rarely used feature. So I think you're right 115 does seem like a better choice.

[Electro Fan]

I can definitely understand it. If this is going to be someone's only meter I'd go with a 17B+ then. If it's a second meter then I would go with a 115, since you can use the uA and temp measurements on another meter.

Muxr, does that mean you would value the microamps feature of the 17B+ over the true RMS of the 115?  I would think that going to a full digit milliamp would suffice but possibly coming up with a wrong AC voltage would potentially be a problem - or maybe I'm not looking at this properly?   This is going to be a first and only (for some time) meter.  EF

[Muxr]

Sorry I edited my post. It's such a tough choice lol. I'd go with a 115 for the first meter then. I think it's more forgiving. When starting electronics, since this is their only meter I assume they don't have a scope. So I think the bargraph can really be invaluable noticing low frequency oscillations (it updates 32times/s on the 115).

[Electro Fan]

Roger that. 

What it shows is that the Fluke people make good DMMs but for all their models you'd think they could offer one right in the middle.  Put a 257s feature and spec set (more or less) in a Fluke "20" body, sell it for $150 and create a legendary product.  I know, I know Lightages, just buy a 257s.  Maybe you should sell them with a 14 day return

[Lightages]

If this is going to be your only multimeter, then having both TRMS and uA would be very good. Limiting yourself to the 17B+ or the 115 means giving up one. The question is which measurement are you more likely to need? Are you going to measuring anything AC that is not basically pure sine wave? Are you going to want to measure low millamps and microamps? Remember just because you can resolve 1mA does not mean it is actually an accurate enough reading.

The 115 is rated at 1% ±3 counts. This means a reading of 1mA could be actually off by 301%! You need the lower range to be available so you can see something more like 1.000uA instead of 0.001mA. The difference in errors on those ranges is very significant with those measurements.

Why would you need TRMS? Are you measuring audio signals? Are you trying to measure the power going to a tweeter in a speaker to be sure it isn't going to fry? Are you measuring power to devices that are temperature sensitive and you need to know the exact AC voltage and current that the device is seeing?

You really should consider another brand IMHO so you can get the functions you want. For close to the same price as the 115 you can get the BM857s. Have a look and ask yourself if having a Fluke is that important to you.
http://www.tme.eu/en/details/bm857s/portable-digital-multimeters/brymen/
People have reported somewhere around $10 shipping to NA.
50000/500000 counts, 0.03% accuracy, dual display, TRMS AC+DC, PC connection option, and many others. It gives up battery life, touch hold, and lifetime warranty against the 115.

Or the AM-270 as I mentioned. $110 and has the two feature you want together, TRMS (AC only) and uA. The back light is a joke though.

The UT139C I referenced is a low priced meter with everything most hobbyists need. What many hobbyists need and don't know until they run into it is that they need two meters at the same time. This is where you can buy two UT139C and have all the capabilities you might need. It is TRMS AC only, and has all he other functions most people would need.

Remember I sell Brymen only South America and make no money recommending it to anyone else. I also make no money recommending Amprobe nor Uni-T. Uni-T has so many crap models it is hard to recommend them but I have the UT139C here I have been using and testing has proven itself to me to be a worthy meter and especially for the price. You can get it from Franky, iloveelectronics here on the forums, for $50 shipped. He will take care of you better than any other retailer I know.

Just so you know, I own a Fluke and have used many of their models over the years, Brymens, Uni-Trends, Digiteks, Mastech  , Metex, one Victor that has been surprising in accuracy over 5 years, UEi, and a couple of others I am probably forgetting. My point is that I understand the confidence in Fluke, but confidence should not over ride your needs in functions. I have as much confidence in Brymen or I wouldn't have started trying to sell them in one of the most difficult markets in the world here in SA. I also make my other brand/model recommendations with the same confidence with the caveats I always include in my recommendations. I make NO money in all the recommendations I have made to you here. I just want to help.

Edited for grammar

[Muxr]

...

Yeah. It sucks how they positioned these lower end meters. This seems to be a common tactic for most market leaders in other industries as well. They sell so many products that they worry about cannibalizing their higher end models with their entry level ones. Canon and Nikon do the same thing with their cameras. They drop seemingly easy features from their lower end products just to differentiate the top models enough.

[Electro Fan]

The 115 is rated at 1% ±3 counts. This means a reading of 1mA could be actually off by 301%! You need the lower range to be available so you can see something more like 1.000uA instead of 0.001mA. The difference in errors on those ranges is very significant with those measurements.

50000/500000 counts, 0.03% accuracy, dual display, TRMS AC+DC, PC connection option, and many others. It gives up battery life, touch hold, and lifetime warranty against the 115.

Lightages, all good points.  Thanks

Two things: 

1 for other folks out there who have a Fluke 115 - can someone check to see if a Fluke 115 reading that should be .001 amps (1 milliamp) really reads as .003 amps (3 milliamps)? or .002 amps (2 milliamps)? Or do you get an accurate reading of .001 amps (1milliamp)?

1 for Lightages - are you pretty sure about the true AC+DC rms capability?

http://brymen.com/product-html/cata250/BM250_Catalog.pdf

In the spec sheet above I didn't see anything about AC+DC rms; per the earlier discussions in this thread a true AC+DC rms capability would enable a DMM to calculate true AC rms taking into consideration a DC offset.  I believe the 257s can do what is referred to as "true AC rms" but I don't yet see something that confirms it does true AC+DC rms.  Maybe I'm just missing it.

Sorry, I saw that you were referring to the 857s, not the 257s.

Thanks, EF

[Lightages]

1 for Lightages - are you pretty sure about the true AC+DC rms capability?

http://brymen.com/product-html/cata250/BM250_Catalog.pdf

In the spec sheet above I didn't see anything about AC+DC rms; per the earlier discussions in this thread a true AC+DC rms capability would enable a DMM to calculate true AC rms taking into consideration a DC offset.  I believe the 257s can do what is referred to as "true AC rms" but I don't yet see something that confirms it does true AC+DC rms.  Maybe I'm just missing it.

Thanks, EF

I pointed to the BM857s. This is MUCH a more capable meter than the BM257s and for basically the same price as the 115. The BM257s is TRMS AC only.

[Lightages]

The 115 is rated at 1% ±3 counts. This means a reading of 1mA could be actually off by 301%! You need the lower range to be available so you can see something more like 1.000uA instead of 0.001mA. The difference in errors on those ranges is very significant with those measurements.

50000/500000 counts, 0.03% accuracy, dual display, TRMS AC+DC, PC connection option, and many others. It gives up battery life, touch hold, and lifetime warranty against the 115.

Lightages, all good points.  Thanks

Two things: 

1 for other folks out there who have a Fluke 115 - can someone check to see if a Fluke 115 reading that should be .001 amps (1 milliamp) really reads as .003 amps (3 milliamps)? or .002 amps (2 milliamps)? Or do you get an accurate reading of .001 amps (1milliamp)?

It could be very well that all 115s will read exactly 1mA when exactly 1mA is applied. You will never know if it is 1.999mA or 1.000mA because it is beyond the capabilities of the 115 to display. Even without any error in accuracy, that is still almost 200% possible error in the actual value. This is not to say that there is anything wrong with the 115, but rather that it is just a fact of life of the resolution of the meter. With this in mind, it is actually possible for the value to be 3.999mA and only read 1mA and still be within the spec of the 115. Again, this is not any bashing of the 115, it is a fact of the resolution and the spec of the 115. So if you want to have "accurate" measurements below 10mA, then you need a different range.

[Electro Fan]

The 115 is rated at 1% ±3 counts. This means a reading of 1mA could be actually off by 301%! You need the lower range to be available so you can see something more like 1.000uA instead of 0.001mA. The difference in errors on those ranges is very significant with those measurements.

50000/500000 counts, 0.03% accuracy, dual display, TRMS AC+DC, PC connection option, and many others. It gives up battery life, touch hold, and lifetime warranty against the 115.

Lightages, all good points.  Thanks

Two things: 

1 for other folks out there who have a Fluke 115 - can someone check to see if a Fluke 115 reading that should be .001 amps (1 milliamp) really reads as .003 amps (3 milliamps)? or .002 amps (2 milliamps)? Or do you get an accurate reading of .001 amps (1milliamp)?

It could be very well that all 115s will read exactly 1mA when exactly 1mA is applied. You will never know if it is 1.999mA or 1.000mA because it is beyond the capabilities of the 115 to display.

If the meter thinks it is reading 1.999mA I think it will display .002 (fwiw, my Fluke 179 reads a PentaRef set for 3.3001 Volts as 3.298 but when I change it to manually read fewer digits it reads 3.30, so I think Fluke knows how to round up and down) but yes I get that the accuracy on the 115 has a pretty wide range - which is why I'd be up for hearing from any Fluke 115 owners who have the ability to test their 115 meters to see if their meters generally go as far out as the spec or if they typically do better to some degree.

[Muxr]

uA/mA range is useful, especially in Electronics. Personally I really don't like the BM857s. It looks like a cheap chinese meter. The backlight on it for instance feels like an afterthought, they just stuck some green LEDs behind, they didn't even bother with a diffuser, probably the worst design for a LED backlight I've ever seen, design looks like a cross between an 87 knockoff and a cheap harbor freight meter.

Brymen BM257s is more modern, is nice and small, and it has all the essentials. Fluke 115 though comes with a proper fast latching continuity tester.

Hold feature on 115 is actually not Fluke's proper auto hold. It's just a hold, very disappointing by Fluke to not implemented their awesome autohold they use on the higher end meters.

If you want a Fluke, I would go with a 115 if you want Brymen I think BM257s would be a nice gift as well.

[Electro Fan]

uA/mA range is useful, especially in Electronics. Personally I really don't like the BM857s. It looks like a cheap chinese meter. The backlight on it for instance feels like an afterthought, they just stuck some green LEDs behind, they didn't even bother with a diffuser, probably the worst design for a LED backlight I've ever seen, design looks like a cross between an 87 knockoff and a cheap harbor freight meter.

Brymen BM257s is more modern, is nice and small, and it has all the essentials. Fluke 115 though comes with a proper fast latching continuity tester.

Hold feature on 115 is actually not Fluke's proper auto hold. It's just a hold, very disappointing by Fluke to not implemented their awesome autohold they use on the higher end meters.

If you want a Fluke, I would go with a 115 if you want Brymen I think BM257s would be a nice gift as well.

Yep, it seems to come down to the 115 and 257s.  I really hate to become a test case but maybe I'll give the 257s a try.  If it doesn't turn out to be a good meter I can dig a conservative hole and just stay there

[PedroDaGr8]

The 115 is rated at 1% ±3 counts. This means a reading of 1mA could be actually off by 301%! You need the lower range to be available so you can see something more like 1.000uA instead of 0.001mA. The difference in errors on those ranges is very significant with those measurements.

50000/500000 counts, 0.03% accuracy, dual display, TRMS AC+DC, PC connection option, and many others. It gives up battery life, touch hold, and lifetime warranty against the 115.

Lightages, all good points.  Thanks

Two things: 

1 for other folks out there who have a Fluke 115 - can someone check to see if a Fluke 115 reading that should be .001 amps (1 milliamp) really reads as .003 amps (3 milliamps)? or .002 amps (2 milliamps)? Or do you get an accurate reading of .001 amps (1milliamp)?

It could be very well that all 115s will read exactly 1mA when exactly 1mA is applied. You will never know if it is 1.999mA or 1.000mA because it is beyond the capabilities of the 115 to display.

If the meter thinks it is reading 1.999mA I think it will display .002 (fwiw, my Fluke 179 reads a PentaRef set for 3.3001 Volts as 3.298 but when I change it to manually read fewer digits it reads 3.30, so I think Fluke knows how to round up and down) but yes I get that the accuracy on the 115 has a pretty wide range - which is why I'd be up for hearing from any Fluke 115 owners who have the ability to test their 115 meters to see if their meters generally go as far out as the spec or if they typically do better to some degree.

Give me a bit, I have one at work. I'll test it with my DMMCheck Plus.

[Electro Fan]

more.... thoughts / info....

Seems like the Greenlee DM-510A is the same meter - although it's somewhat hard to see if the 510A is the equivalent of the original 257 or the newer 257s - or if there are any advantages to buying a Brymen vs. a Greenlee product.  (Greenlee might have a better warranty in the U.S.).

http://www.amazon.com/Greenlee-DM-510A-Professional-Digital-Multimeter/dp/B003TO5YU0/ref=cm_cr_pr_pdt_img_top?ie=UTF8

Some excerpts from some of the reviews:

http://www.amazon.com/Greenlee-DM-510A-Professional-Digital-Multimeter/product-reviews/B003TO5YU0/ref=cm_cr_pr_viewopt_srt?ie=UTF8&showViewpoints=1&sortBy=recent&reviewerType=all_reviews&filterByStar=all_stars&pageNumber=1

(Overall, pretty positive reviews except for a few things.  Limited LED testing (max out at 1.5V?), plastic smell?, so-so continuity? so-so tilt bale, back light only stays on for 30 seconds?.  Maybe some 257s users can comment on whether these are correct or notable issues.  Seems like a DMM should be able to test diodes with better than 1.5V, and the smell issue wouldn't be nice but maybe it's a personal thing for someone sensitive to smells or maybe it goes away?  It would be nice to have a sturdy bale.  If the biggest issue is the light turns off after 30 seconds that would be not be much of a problem.)

Review excerpts

I have an old DM-200 and I have dropped it tens of times and it still works perfectly. I bought the DM-510a because it has true RMS voltage measurement, temperature, and capacitance measurements. With the optional cable, you can hook it up to a PC for logging. This unit is quick and as accurate as any portable DMM on market. It's every bit as good as the Fluke meters we have and costs less with a lifetime warranty. Fluke used to be made in the U.S., but not anymore. Most of their meters are made in China, with a couple of exceptions.

---

This is meter does just about everything, and the size is great too. I first bought the 830A, which is super meter but it was *huge*. This meter has almost all the same functions (no conductivity, no Dbm) and it's *way* smaller.
I would say that these Greenlee meters have way more value than Fluke, but it's more than that... Fluke doesn't even *make* one meter with all these features, so this was my only choice.
I love it.

---

I have the identical OEM version of this meter (Brymen BM257). Build quality is excellent and consistent with its rather conservative CAT ratings. Other pros are: good refresh rate; big display digits; excellent probe set; nice rubber holster. Cons: wimpy tilt bail; so-so range switch; back of meter case feels cheap and not tightly fitting; latching continuity beeper is a bit slow; pricey

---

Has that, Oh so Sweet! toxic Chinese plastic (test leads) and rubber smell (protective holster). Do not touch yourself after handling this meter. Wash your hands after using it. The range switch on this unit is small even for someone with small hands. Also, the bar graph is slow while tracking measurements (not like the Fluke's). This unit should have been made a little bigger with a larger range switch. Overall it is not a bad unit, but I am going to have to fail it (two stars) because it is not value for your money, especially after Greenlee did not include the adapter and software for a PC. Otherwise, I would have given it three stars.

I place the fair market value of this meter at around $80. Let's get it there. I returned mine to Amazon for a refund.

---

This meter is really good, except for 1 major flaw that made me return it. There are also a couple minor annoyances that are not show stoppers, but not good in my opinion.

DCV and ACV
This meter has excellent accuracy and is a True RMS meter. It also has a high number of counts for a very good precision reading.

Continuity
The continuity test is so so. It is very fast response, but is not latching. Has a scratchy sound to it, which I don't like. In general you can live with it since it is very high speed, but a latching beep would have made it aces.

Backlight
The meter has a really nice backlight. Only issue for me is that when you shut off the backlight, it stays on only for 30 seconds. Not cool. When I turn on the backlight, I want the backlight to stay on until I shut it off.

Rec function (aka Min Max)
The record function is good, but lacks a "Fast min/max" mode for high speed transient detection.

Diode Test
Checks standard diodes fine, but can't test even a red LED. This is a show stopper to me. The meter only outputs 1.5V for the diode check, so it can't forward bias even a standard Red LED with a 1.6 forward voltage. My bremen 869 puts out 3V, and the fluke can even forward bias a white LED. A 1.5V diode test is inexcusable these days. Even my 25 year old Fluke 29 puts out 2.9V on the diode test function.

Hold Function
The hold function is just OK. when you have a value on the screen and hit hold, it will lock the value into the display. This is ok, but not nearly as useful as the fluke AutoHold feature. AutoHold lets you set it, then take your measurement, and the meter will automatically hold the reading for you. For instance, if you hit autoHold, then measure the resistance of a resistor, you will hear a beep and the meter will have locked in the value of the resistor. This is a very handy feature, and one that a Vanilla hold really misses.

Overall this is an excellent meter, that is built well, will be safe to use even at mains voltages (CAT iV rated). Brymen is the OEM of this meter which is sold as the BM-257. It is a good meter that will last a long time. Just don't rely on it for LED testing.

[Electro Fan]

Give me a bit, I have one at work. I'll test it with my DMMCheck Plus.

Pedro, Thanks

EF

[PedroDaGr8]

Give me a bit, I have one at work. I'll test it with my DMMCheck Plus.

Pedro, Thanks

EF

Damn, just checked, I have a 116 not a 115.

Sorry.

[Electro Fan]

No worries - feel free to let us know about any features that are the same on the 115 and 116, or any other thoughts on the 116.  Thx

[Electro Fan]

Any chance that some of our Spanish speaking EEVers could let us know if there is anything good to learn from this video?

Brymen 257s and Fluke 87V



Thanks

[Muxr]

Give me a bit, I have one at work. I'll test it with my DMMCheck Plus.

Doubt you'll be able to get much valuable information using the DMMCheck Plus. I just tried mine on the 87V and a 27 in the Amp range and DMMCheck's 1mA output barely registers. Lightgages is right. Measuring down to a few mA will not really be spot on, on a meter with just Amp measurement.

For a lot of stuff a measurement within a few mA is sufficient, also you can use your own shunt resistor to measure current. But it's definitely a big shortcoming of the 115 when it comes to electronics work and performing accurate small current measurements.

One thing I noticed on these Brymen meters is that they don't have Min/Max mode. This is really handy in a variety of situations. Especially for someone who doesn't own a scope.

[Electro Fan]

Give me a bit, I have one at work. I'll test it with my DMMCheck Plus.

Doubt you'll be able to get much valuable information using the DMMCheck Plus. I just tried mine on the 87V and a 27 in the Amp range and DMMCheck's 1mA output barely registers. Lightgages is right. Measuring down to a few mA will not really be spot on, on a meter with just Amp measurement.

For a lot of stuff a measurement within a few mA is sufficient, also you can use your own shunt resistor to measure current. But it's definitely a big shortcoming of the 155 when it comes to electronics work and performing accurate small current measurements.

One thing I noticed on these Brymen meters is that they don't have Min/Max mode. This is really handy in a variety of situations. Especially for someone who doesn't own a scope.

Don't know why the 87V should have any challenge with this.  On my DMMCheckplus set for 0.9996mA DC my Fluke 179 reads 1.00mA and for 1.000mA AC it reads 1.01.  I don't know which has drifted the Checkplus or the Fluke but you can get to hundredths of a mA on the 179.  But in any event it would be good to get beyond the single digit milliamp readout of the Fluke 115 so the Brymen is looking attractive - if it just smells ok (not too much plastic aroma), and hopefully it can power a red LED. 

[Muxr]

Give me a bit, I have one at work. I'll test it with my DMMCheck Plus.

Doubt you'll be able to get much valuable information using the DMMCheck Plus. I just tried mine on the 87V and a 27 in the Amp range and DMMCheck's 1mA output barely registers. Lightgages is right. Measuring down to a few mA will not really be spot on, on a meter with just Amp measurement.

For a lot of stuff a measurement within a few mA is sufficient, also you can use your own shunt resistor to measure current. But it's definitely a big shortcoming of the 155 when it comes to electronics work and performing accurate small current measurements.

One thing I noticed on these Brymen meters is that they don't have Min/Max mode. This is really handy in a variety of situations. Especially for someone who doesn't own a scope.

Don't know why the 87V should have any challenge with this.  On my DMMCheckplus set for 0.9996mA DC my Fluke 179 reads 1.00mA and for 1.000mA AC it reads 1.01.  I don't know which has drifted the Checkplus or the Fluke but you can get to hundredths of a mA on the 179.  But in any event it would be good to get beyond the single digit milliamp readout of the Fluke 115 so the Brymen is looking attractive - if it just smells ok (not too much plastic aroma), and hopefully it can power a red LED. 

I used the A mode not the uA mode. To simulate what a user would do with a 115, since 115 only has the A mode.

In uA mode 87V shows exactly 1000 uA which is what my DMM Check Plus cal sheet shows.

[PedroDaGr8]

No worries - feel free to let us know about any features that are the same on the 115 and 116, or any other thoughts on the 116.  Thx

The 116 is more of an HVAC meter I think. It drops A, adds uA, Temp and LoZ.


My feelings on the meter, it's competent but nothing amazing. How it feels in the hand is very mediocre, the selector feels cheap (a bit loose and a bit rough, not at all like the 87V I used to have). I will do a full review on it at some point soon. The leads say they say they are TL75 but they feel pretty so so; they are not at all soft like my Pomona leads. The backlight is VERY dim. The dimmest of all of the meters that I have used, in sunlight you can't tell when it turns on. Continuity is latched and the turn on is fast but the turn off is a bit slow. Such that if I run the tips across each other. I can make it miss disconnects.

The good thing is that it meets its specifications and does it time and time again. Additionally, knowing Fluke it will be safe (even though it has no fuses).

[Electro Fan]

Give me a bit, I have one at work. I'll test it with my DMMCheck Plus.

Doubt you'll be able to get much valuable information using the DMMCheck Plus. I just tried mine on the 87V and a 27 in the Amp range and DMMCheck's 1mA output barely registers. Lightgages is right. Measuring down to a few mA will not really be spot on, on a meter with just Amp measurement.

For a lot of stuff a measurement within a few mA is sufficient, also you can use your own shunt resistor to measure current. But it's definitely a big shortcoming of the 155 when it comes to electronics work and performing accurate small current measurements.

One thing I noticed on these Brymen meters is that they don't have Min/Max mode. This is really handy in a variety of situations. Especially for someone who doesn't own a scope.

Don't know why the 87V should have any challenge with this.  On my DMMCheckplus set for 0.9996mA DC my Fluke 179 reads 1.00mA and for 1.000mA AC it reads 1.01.  I don't know which has drifted the Checkplus or the Fluke but you can get to hundredths of a mA on the 179.  But in any event it would be good to get beyond the single digit milliamp readout of the Fluke 115 so the Brymen is looking attractive - if it just smells ok (not too much plastic aroma), and hopefully it can power a red LED. 

I used the A mode not the uA mode. To simulate what a user would do with a 115, since 115 only has the A mode.

In uA mode 87V shows exactly 1000 uA which is what my DMM Check Plus cal sheet shows.

Roger that - I missed where you said measured in the Amp range.

[Lightages]

uA/mA range is useful, especially in Electronics. Personally I really don't like the BM857s. It looks like a cheap chinese meter. The backlight on it for instance feels like an afterthought, they just stuck some green LEDs behind, they didn't even bother with a diffuser, probably the worst design for a LED backlight I've ever seen, design looks like a cross between an 87 knockoff and a cheap harbor freight meter.

Sorry but you are referring to the BM857A which had the poor back light. The BM857s has a full back light that is very nice and the model is UL listed with CATIII/1000V and CATIV/600V on the latest IEC requirements. It is built like a brick outhouse and has more features than the BM257s, and a whole other class of accuracy. I misspoke when I said it has dual display, it does not. It does not have temperature measurement if that is important.

Brymen BM257s is more modern, is nice and small, and it has all the essentials. Fluke 115 though comes with a proper fast latching continuity tester.

Yes, I agree the BM257s looks nicer, but for the same price as the 115, the BM857s is more capable IMHO.

[PedroDaGr8]

Hold feature on 115 is actually not Fluke's proper auto hold. It's just a hold, very disappointing by Fluke to not implemented their awesome autohold they use on the higher end meters.

If the latching continuity is anything like the 116, the turn on is nice and fast but the turn off is not fast enough. I can easily make it skip disconnects when running the probes across each other.

[Lightages]

more.... thoughts / info....

Seems like the Greenlee DM-510A is the same meter - although it's somewhat hard to see if the 510A is the equivalent of the original 257 or the newer 257s - or if there are any advantages to buying a Brymen vs. a Greenlee product.  (Greenlee might have a better warranty in the U.S.).

Yes you get the Greenlee lifetime warranty. What it really means is still up in the air until I here from Greenlee. I do not know if their model is the equivalent to the "s" version or not.

http://www.amazon.com/Greenlee-DM-510A-Professional-Digital-Multimeter/dp/B003TO5YU0/ref=cm_cr_pr_pdt_img_top?ie=UTF8
(Overall, pretty positive reviews except for a few things.  Limited LED testing (max out at 1.5V?), plastic smell?, so-so continuity? so-so tilt bale, back light only stays on for 30 seconds?.  Maybe some 257s users can comment on whether these are correct or notable issues.  Seems like a DMM should be able to test diodes with better than 1.5V, and the smell issue wouldn't be nice but maybe it's a personal thing for someone sensitive to smells or maybe it goes away?  It would be nice to have a sturdy bale.  If the biggest issue is the light turns off after 30 seconds that would be not be much of a problem.)

Yes, the diode test is only good to 1.5V, on the BM857s it is around 2.9V (measured). The tilt bale is nothing special but it is basically unbreakable. Yes, the back light is only on for 30 seconds. I hate that in a multimeter. There should be an option to keep it on indefinitely if you choose. This is not just a problem for Brymen. I did not detect any weird smells from any Brymen I have looked at, and that is dozens. The test lead type is an option for the reseller to ask for. There are two types, one with stainless steel sharpened tip but with stiff insulation, and the other with gold plated tips with silicone insulation. I prefer the gold tipped version.

[Lightages]

Any chance that some of our Spanish speaking EEVers could let us know if there is anything good to learn from this video?

Brymen 257s and Fluke 87V

Thanks

He is just going over his need for a smaller alternative to the 87V and he likes the BM257s. He goes over the functions and likes and dislikes. The only real dislike that I could see is that he missed the autohold on the 87V. But as Muxr pointed out, the 115 doesn't have that feature.

There is no need to search videos for Brymens if you want direct answers. I have tested and used the BM257s, BM857s, BM829s, BM869s, BM525, BM27, BM22 and the BM089 clamp meter.

Why don't I tell you about the things I don't like about the BM257s? I would much prefer it had TRMS AC+DC instead of just AC, I wish there was an option to enable the back light to be on till I want it off, and I would like it to measure all types of LEDs. As far as the AC+DC function, there are work arounds with measuring in AC and DC mode and making some calculations, but that isn't very convenient.

What don't I like about the BM857s? The back light timeout again, the lack of temperature measurement, and it could have better battery life. There is so much more in the BM857s over the BM257s that if you are looking at FLuke 115 prices it is a big contender.

In the end I would not be ashamed to own the Fluke 115, nor the 17B+, nor a BM257s, nor the BM857s. It comes down to your level of confidence in what you are buying is going to meet your needs in the long run.

[Fungus]

Yep, it seems to come down to the 115 and 257s.  I really hate to become a test case but maybe I'll give the 257s a try.  If it doesn't turn out to be a good meter I can dig a conservative hole and just stay there

If it's for a present then:
a) Maybe 'big and yellow' trumps 'features' when you're at college (17B+ way cooler than BM257).
b) Maybe TRMS isn't as important to him as the engineers here are imagining.

The 17B+ is a pretty good multimeter for a student

(In fact, it's a pretty good multimeter, period. I certainly wouldn't turn one down...)

[Electro Fan]

After looking at the images some more it looks like maybe the Greenlee 510A is the Brymen 257, not the 257s.  Note the 510A and the 257 both are marked 8A (Amps) vs. 10A on the 257s.

[Lightages]

Then yes, you are right, the Greenlee is not the S version. It is still a great meter either way.

[kasone]

Electro Fan,  I don't know if you have purchased your meter yet, but in the for sale section there is a new in the box Fluke 117 for $75.00 from a USA seller. It was a new listing yesterday. You may be interested.

[Fungus]

Electro Fan,  I don't know if you have purchased your meter yet, but in the for sale section there is a new in the box Fluke 117 for $75.00 from a USA seller. It was a new listing yesterday. You may be interested.

If I was a college student I'd rather have a meter with mA/uA and temperature.

[Marco1971]

Finally, as mentioned earlier, for excellent results in all situations a true AC+DC rms meter is required, which interestingly is not something included even in the highly regarded (by some/many) Fluke 87V.

Yes, No?  Thanks again

Yep, for TRMS AC + DC and displaying "both" at the same time, only at 287/289 series if we're talking only Fluke brand.

Hi, not limited to 287/289 models, 89IV and 189 did the same (page 38)

http://assets.fluke.com/manuals/87_89iv_umeng0300.pdf

Marco