Thinking of buying a multimeter. - Page 1
Forum section: electronics / testgear

author: adrianf88
author_rank: Contributor
timestamp: April 17, 2014, 11:34:52 pm
content: First i would like to say hello to everybody, I'm a big fan of Dave's channel and quite possibly, i can "blame" him for my hobby.I started out with a cheap, and i do mean cheap multimeter which i bought for about 15$.This one to be more exact. Same model, same brand....http://img.diytrade.com/cdimg/2159999/33940157/0/1385965308/best_digital_multimeter_dt9208a.jpgA good enough multimeter for my little electronics projects but lately, it's been acting up. I tried measuring a simple AA (R6) battery and the reading was all over the place. Started at 10.4V and then settled after a few seconds at 1.43V but then spiked back up to around 7V. So i believe it's his time to retire from service. So i began looking for a decent meter for around 60$. Cheapies as Dave would call them but for my budget, i would call that top dollar!) It's intended use would be small electronic projects, measuring components like resistors, caps, etc. Small voltages, currents and on occasion, power outlets around the house, blown fuses and stuff like that. I would like to be able to read a temperature now and then to see if a heat-sink is doing it's job during a build.I had a look around and finally found some contestants:Uni-t UT61E, UT61B, UT60H.But...UT61E doesn't measure temperatureUT61B isn't True RMSand i can't find anywhere a teardown of the UT60H (which is both true RMS and measures temp.) so see how it is built (if it uses HRC fuses like the UT61B(E), how's the board layout, the shielding or if it's anywhere near as safe as the UT61)So... My questions are:Does anybody know how the UT60H looks like on the inside? Does it use HRC fuses or glass ones?Do you know any similar multimeter than can do what the UT60H can do for the same price?Thank you so much for taking the time to read this entire post and i look forward to hearing your opinion.P.S. If i messed something up and you don't understand something, i apologize. English isn't my first language.

author: Electric flower
author_rank: Regular Contributor
timestamp: April 17, 2014, 11:57:05 pm
content: I own 61E and im quite happy with it, as it comes to measuring temperature, as a beginner (like me) you can get away with measuring voltage generated by thermocouple probe when it is heated, (look at Dave's video about thermocouples).There are plenty of K type thermocouple graphs that let you see connection from voltage generated to a temperature. PM me if you want some info about 61E or something else, there are 4 videos of 61E done by Mjlorton on Youtube.60H was also on my list of choices as well as 61E, i went with 61E becouse it was cheaper, 60H looks better than 61E but i can't say for shure.

author: tld
author_rank: Regular Contributor
timestamp: April 18, 2014, 12:02:23 am
content: Hi,Just thought I'd mention that at least for me, there's no big win in having a temperature-function on the multimeter itself. Sure, could be handy, bit if I'm measuring temperature-rise, there's a good chance I'd want to measure current-draw at the same time.Having a separate unit for measuring temp might be more handy, and there's plenty of decent cheap ones available.At least of the uni-t models you mention, I'd prefer the 61E, and separate temp measure.tld

author: PedroDaGr8
author_rank: Super Contributor
timestamp: April 18, 2014, 12:05:53 am
content: Temperature devices are cheap:http://www.ebay.com/itm/TM-902C-Digital-Thermometer-new-version-0-1-degree-resolution-50-to-1300C-/200902258791This is sold by a forum member Franky (iloveelectronics)He's an awesome guy with great prices. He also sells the UT61E for $57https://www.eevblog.com/forum/buysellwanted/brand-new-uni-t-ut61e-for-sale/He might be able to combine shipping to reduce the cost a bit for you.

author: adrianf88
author_rank: Contributor
timestamp: April 18, 2014, 12:14:16 am
content: Hey! Thank you everyone for the fast reply! I know the UT61E is a favorite around here, and that's the reason it's a contender in my list, but i would really, really like to be able to measure temperature too. I took a look at Franky's store on ebay, (BTW, thanks for the info!) and he also sells the UT139C whichs is both True RMS and can measure temperature. Any thoughts about that?And i know the UT60H looks goodbut how is it built? Anybody around here knows?

author: dannyf
author_rank: Super Contributor
timestamp: April 18, 2014, 12:18:26 am
content: I have had quite a few DT830 and a DT930, some dating back to the 1980s. They have all worked every well, and the last one I have was $5.I really don't see the point of buying anything else.

author: Wytnucls
author_rank: Super Contributor
timestamp: April 18, 2014, 05:55:59 am
content: The 139C is one of the latest UNI-T meters. The company seems to take input protection a bit more seriously these days. On paper, it looks all good. A few of the drawbacks are the lack of a bar graph and a PC connection.Don't expect stellar performances in that price range, but it should be good enough for your needs.

author: retiredcaps
author_rank: Super Contributor
timestamp: April 18, 2014, 06:07:18 am
content: For the $60 budget, you may want to consider the Digitek DT-2843RLightages, a member here, did a reviewIt has True RMS and temperature measurement. I can't say that I ever needed True RMS though.Franky also sells the meter.http://www.ebay.com/itm/171080136251

author: retiredcaps
author_rank: Super Contributor
timestamp: April 18, 2014, 06:10:45 am
content: Quote from: adrianf88 on April 17, 2014, 11:34:52 pmIf you want to try and fix the existing meter, I suggest1) try a fresh battery. Sometimes a marginal battery gives funny readings, but the meter does not display the low battery icon on the lcd.2) try different probes. You may have broken wires inside your probes?3) check the rotary switch. Give it a good IPA cleaning.4) check the soldering on your input jacks. Maybe there is a bad solder joint?5) give your PCB and good IPA bath and cleaning.6) check your input impedance. You may have a bad PTC or some marginal component?

author: retiredcaps
author_rank: Super Contributor
timestamp: April 18, 2014, 06:13:05 am
content: Quote from: dannyf on April 18, 2014, 12:18:26 amEveryone has different requirements. While a $5 830 works well for your purposes, it may not work well for others.Just like a Fluke is overkill for some, others depend on its safety ratings, reliability and customer service.

author: han
author_rank: Frequent Contributor
timestamp: April 18, 2014, 06:30:00 am
content: Quote from: retiredcaps on April 18, 2014, 06:13:05 amEven fluke can be unsafe for some people

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: April 18, 2014, 06:55:04 am
content: Quote from: adrianf88 on April 18, 2014, 12:14:16 amI actually own a UT60H myself. Bought it when I first got back into the hobby a couple of years ago, before I became a sellerIf I remember correctly it uses only glass fuses. I don't like the meter much as it's slow, in terms of screen update rate, auto ranging, as well as the continuity tester.The UT139C would actually be my personally recommendation if you do not need the higher resolution and PC connectivity of the UT61E.BTW, thanks everyone for recommending me again! I'm really grateful for all your support!Cheers,Franky

author: adrianf88
author_rank: Contributor
timestamp: April 18, 2014, 08:33:37 am
content: Thank you everybody for all the replies! What a wonderful community! Usually i get my head chewed off for being a newbiebut i see here is not the case! Anyway, thank you again, and thank you Franky for clearing that up for me. The UT60H is a no go for me as of right now. So the only 2 meters left are the UT61E and the UT139C. I love the UT139C but i have to wonder.... Why is it cheaper than the UT61E when it has more features? I love the NCV feature and i also love the backlight feature but again... why is it cheaper? Inside it looks better built than the UT61E. And also i never worried about the counts since i never needed more than 2 decimals on my readings, but after seeing the video i have to wonder.... If i measure anything below 6V it will read 5,123V right? If i go over 6 it will read 6,12V. But what will happen if i go over 60? Will i get only one decimal? like 60,5V or 100,2V? That will definitely be a no go for me...And also, why can't i find the UT139C on the UNI-TREND site? Or anywhere else for that matter besides ebay?

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: April 18, 2014, 08:49:24 am
content: The UT61E is more expensive mainly because of the higher count, and the data logging capability to a PC.A 6000 count meter means the maximum display you will see on the screen is 6000 (technically it's 5999), regardless of the position of the decimal point. So yes, you will read 5.xxxV before you hit 6V, and 6.xx after that (because it cannot display 6xxx). You have will 2 decimal places until 59.xxV and then down to one decimal place after 60.xV.

author: adrianf88
author_rank: Contributor
timestamp: April 18, 2014, 08:59:05 am
content: Thank you Franky for the fast reply! I'll have to think about that... But thank you everybody for all the help! And as soon as i make a decision, i'll contact Franky to buy one. Either one or the other!

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: April 18, 2014, 09:14:00 am
content: They do have more info of the UT139C on the Uni-T website, but only on the Chinese version website.http://www.uni-trend.com.cn/cp-show.asp?yy=%D6%D0%CE%C4&ProductNO=780

author: adrianf88
author_rank: Contributor
timestamp: April 18, 2014, 09:52:39 am
content: Thank you again Franky! Now i know the UT139C is a legit meter. And not just a Chinese toy. And i would buy it right now if it wasn't for that pesky low count number... Does UNI-T make a UT139D or E or F or anything similar that would have the same specs as the UT139C but with a bigger count? Because i love the NCV feature, the backlight, the temperature, the build quality and also the fact that it uses AA batteries. But if i could have 2 digits up to 100V like 100,xxV it would be the perfect meter and i would buy it right now!

author: Wytnucls
author_rank: Super Contributor
timestamp: April 18, 2014, 09:56:41 am
content: Don't fuss too much about count and accuracy with cheap meters, as they drift quite a bit over time. Their very basic voltage references are internal to the main DMM chips, which are surrounded by the cheapest components available.Rather base your decision on the features that you need the most.

author: adrianf88
author_rank: Contributor
timestamp: April 18, 2014, 10:11:09 am
content: Hello there! Trust me, i'm not fussing about precision. I don't want 6 digits and i don't expect very accurate readings for the price. And by accurate i mean getting a read of 10,123456V from a 10,123456V source. But what i do need is at least 2 digits up to 100V. Like 100,12V. My main hobby is LED's right now and working with constant current sources is a bit of a fuss. So if i were to need, let's say 200,5 mA, the difference between 200,51 mA and 200,59 mA could cause the LED's to burn out. So if anybody knows a multimeter with the exact same specs as the UT139C but with a bigger count please let me know. I believe i could cut back on the NCV feature... So maybe a UT139C without NCV but with a bigger count?

author: KJDS
author_rank: Super Contributor
timestamp: April 18, 2014, 10:13:31 am
content: Quote from: adrianf88 on April 18, 2014, 10:11:09 amAre you really using 0.01% resistors and similar parts for an LED?

author: davidefa
author_rank: Contributor
timestamp: April 18, 2014, 10:32:55 am
content: ut139c review and teardown:user manual:http://www.pinsonne-elektronik.de/media/daten/UT139A_B_C_eng_uni-t_pinsonne.pdfP.S. 0.1mA will not hurt your led

author: adrianf88
author_rank: Contributor
timestamp: April 18, 2014, 10:38:06 am
content: Nope. But i built quite recently an LED lamp with a bunch of LED's and it required a constant current source of 320,5 mA maximum. And i had to test everything very carefully, pots, resistors, everything so i wouldn't go over 320,5 mA and even if i didn't use 0,01% resistors, the output needed to be precisely tuned in order for the LED's not to burn out. And since then i began a lot of small electronics projects involving LED's. In some i needed the extra precision, in some i didn't. And i don't just use resistors for my LED projects. I use something like this as the power source:

author: Wytnucls
author_rank: Super Contributor
timestamp: April 18, 2014, 10:39:53 am
content: Measuring currents accurately is not an easy matter, even for expensive meters.Quoted accuracy for the 61E on DCmA is 0.5%+10 counts. So the last digit is irrelevant if you measure 200.05mA, anyway.With low voltages, the problem is even more acute, as now you have the 61E burden voltage to deal with.With AC, accuracy is quoted as 1.5%+50 counts above 1kHz, so let's not even go there.

author: Wytnucls
author_rank: Super Contributor
timestamp: April 18, 2014, 10:59:02 am
content: The only other meter available in that price range I can think of, with a high 22,000 count, true RMS and temperature, is the Victor 86E.Quality is not one of their strongest suit though...http://www.china-victor.com/english/en/product_data.aspx?ClassID=168&ID=313http://www.fasttobuy.com/digital-multimeter-victor86e-victor-86e-digital-multimeter-usb-interface_p4360.html

author: KJDS
author_rank: Super Contributor
timestamp: April 18, 2014, 11:03:49 am
content: If you want anything* electronic to last, run it at 50% of its rated maximum.There are exceptions to this, mostly in power devices that get more efficient as you get close to their maximum rated power, but for turning an LED on it's the way to go. Have a look at how resistance changes with temperature, and remember that running a current through a resistor will change its temperature. Find out what the LED volt drop does with time and temperature and you'll be able to run it closer to max, but in general it takes a great deal of understanding to run anything hard without releasing magic smoke and saying it will be fine at 300.5 but not at 300.9 isn't the right approach.

author: adrianf88
author_rank: Contributor
timestamp: April 18, 2014, 11:48:06 am
content: Thank you everyone for the patience and for all of the great advice! I settled on the UT139C, and come next paycheck, i will contact Franky and buy one from him since everyone around here seems to recommend him! Thank you again for all the help and for being so nice with a newbie! Have a wonderful day!P.S. Franky, have you ever shipped to Romania? If so do you know if i have to pay any charges? Import taxes and stuff like that?

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: April 18, 2014, 12:07:17 pm
content: Quote from: adrianf88 on April 18, 2014, 11:48:06 amYes, I have shippped a lot of packages of different sizes to Romania and as far as I know my customers there rarely have to pay customs/tax. Obviously I can't guarantee anything though as ultimately I have no control over it.

author: LaurenceW
author_rank: Frequent Contributor
timestamp: April 18, 2014, 05:24:29 pm
content: Hold on, Hold on. Why do you think you need to drive an LED or LED array to such precision as 320.05mA? I suggest that, quite simply,You Don't!. Drive them at 300 mA or 350mA, or anything in between, and I'll bet that you will scarcely notice any difference in the light output, and any impact on LED life expectancy will be so minimal as to be irrelevant.LED currents just aren'tthatcritical. Neither, then is such a precision current source. If your circuit supply voltage is itself stable to within +/- 5% (or even +0-20% if it's battery operated) I would suggest that that is plenty close enough to be used as a reference. If you still wantsomesort of voltage reference independent of supply, a small zener or a couple of signal diodes in series will do, but not the cost of a precision reference. In practice, the LEDs just don't warrant it.Rule of Thumb: unless you are working with instrumentation equipment which actuallyneedsto record voltages to such degrees of accuracy, don't bother designing anything to a precision of more than two significant figures. You are wasting your time, will probably end up wasting money on over-tollerance parts, for no discernable impact on the overall circuit performance. You design calls for a 1.2K resistor, and you only have 1K to hand? - she'll do - bung it in!

author: adrianf88
author_rank: Contributor
timestamp: April 18, 2014, 06:00:45 pm
content: Hey there LaurenceW! Thank you for the imput! I don't need it to 350.05 but i did need it to 350.5 at the time. Or to be precise at 350.4. Why? Because i had 16 LED's with a maximum tolerance of 22mA and i wanted to run them at their peek performance without blowing them out. So i settled for 21.9mA for each, totaling a 350.4 mA draw. At least that was my logic. Could i have powered them at 21 mA? sure! 20? Sure! But i wanted absolute peek performance without killing them. So i decided at 21.9 mA. That lead me to a constant current source of 350.4 mA. And trust me, at even 23 mA per LED, those LED's burned out. As to the design, that's what i found during a quick search on google. Not my design, don't even know if it's any good. Was just a proof of concept, because somebody asked if i needed 0.01% precision on resistors. He believed i meant resistors when i mentioned of powering LEDs. Anyway, let's not drift offtopic.Thanks yet again to everyone for the help. I'm now just waiting for the next paycheck to buy this puppy!

author: LaurenceW
author_rank: Frequent Contributor
timestamp: April 18, 2014, 07:50:09 pm
content: Hello again, Adrian,I think KJDS was "pulling your leg" when he asked about the 0.1% resistors! He was really making the same point - really, you just don'thaveto by that precise in all this. Sure, the constant current circuit that you havewillwork, and no doubt beautifully, but it's overkill, that's all.When manufacturers give ratings to their products, they are usually pretty conservative, and figures are specified over a wide range of temperatures and typical component tolerances. There is a good safety margin built in. An LED rated at 22mA will happliy run at 25, even 30mA for many thousands of hours. If you are experiencing LED failures, I will bet my best shirt on the fact that it isnottriggered by minor current overload against some specification figure.Even different LEDs from the same manufacturing batch will perform a few % differently with respect to one another. Put a few in series and parallel, and you will find minor variation in the voltage across each LED, across each string, and also differences in the current flowing in each string, that make trying to drive anexactcurrent through each LED nigh on impossible. But they'll all still work fine.Now, such a small current LED, accidently exposed to, say, 1A even for just a few mS may well fry. That will be enough energy and time to burn the delicate LED die out. A simple wiring fault or incorrect component in a driver circuit could easily lead to that.Here's another thought. Our ears, eyes, and for all I know, probably our noses respondlogarithmicallyto changes in sound/light and smell. This is rather handy, as it enables them to operate over a HUGE RANGE of values. Compared to the very quietest sound you can hear and the point at which the sound is so loud it actually hurts, the ratio of sound pressure is 1:1,000,000,000,000 - that's a million million! And this is one reason why we measure sound levels in decibels, instead (a much more manageable measure). Moreover, ears can bearly detect a 1dB change in sound level, and yet this corresponds to a level change of 25% in the absolute level of the signal.Now, I don't know what the threshold is for eyes, but I will put another of my shirts on the fact that, if you built a circuit to drive your LED with first 20mA for 1 second, then 22mA for a second, and then repeat this,your eyes would not be able to see the change in level of illumination.And even if they could, it would be so small that, when shown either brightness in isolation, you'd hve no reall idea whether you were looking at 20 to 22mA.Bottom line is - yes, youcanspecify and build to this level of precision, but it yields no advantages in the workings of your circuit, whatsoever. And, at the risk of running out of shirts alltogether, I'll state that no 20mA-rated LED will give up the ghost at 23mA. There, I've said it.Please don't let me put you off - Keep experimenting and Learning! It's all good.

author: adrianf88
author_rank: Contributor
timestamp: April 18, 2014, 09:23:36 pm
content: Ohhhhhh, don't tell me about overkill cuz with that led lamp i shot the proverbial ant with an elephant gun! But it pissed me off that the LED's in the original lamp burned out pretty fast so i went out and bought some better LED's. After that i wanted a longer life for the lamp and so i decided to build a constant current source and boy do they work beautifully now! And don't tell me that there's a single hobbyist on this forum that didn't build something overkill just because he could cuz then i would have to throw some of my shirts in the mix!Or maybe just out of spite. Or maybe in a moment of pure madness he wanted something that would survive an nuclear war... Whatever, but i bet everyone around here built something overkill.And yeah, like i said previously, i could have powered them at 20mA or even 19... but i just wanted maximum power. It was my crotchet. Who can blame me?Also i appreciate all the time and effort you put in all your replies but i have to (i'm sorry but i hope you understand) take you up on that bet. *here take my shirt*The LED's i used were rated for different currents. I don't remember the exact numbers but it was something like this:10mA - 2lm15mA - 4lm20mA - 6lmmax 22mA - 7lmwith 15.000 h of life at 15mA or something like that...And i tried pushing 23mA thru 1 LED's and it did burn out!So i just decided to power them at 21,9 mA which was just below their maximum rating...On the other hand i know that an led rated at 20mA won't die at 23mA but these were rated way below that. Their maximum supported current was 22mA!Anyway... long story short, i had to build that, i don't know if i actually succeeded knowing now what Wytnucls said about multimeter accuracy, but i built it, it still works, and i just thought i could find something to help me better next time. But after all the replies here, i now understand that even the most accurate meter doesn't quite measure current accurately so i'll just stick to the UT139C. Thank you again for all your time and effort and have a wonderful day!

author: Flump
author_rank: Frequent Contributor
timestamp: April 18, 2014, 09:43:39 pm
content: I just bought an Extech EX330http://www.extech.com/instruments/product.asp?prodid=277It's a cheap meter but good on accuracyI checked its dcv accuracy using an AD586LNwhich is 5.000 V +/- 2.5 mVand it read spot onand I used a 620R, 0.5W, 0.1%, 15PPM Resistorand again it was spot on.I used the 1Kz test point on my scope which I know is high and the scope says it is1043hz and the Ex330 reads 1042.Auto ranging seems a bit slow sometimes but i don't mind that as i'm never in a hurryso for a cheap meter i'm very happy

author: PedroDaGr8
author_rank: Super Contributor
timestamp: April 18, 2014, 10:07:23 pm
content: Quote from: Flump on April 18, 2014, 09:43:39 pmmeter is known to have huge issues with build quality. Plus its just a rebranded CEM.

author: Flump
author_rank: Frequent Contributor
timestamp: April 18, 2014, 10:29:34 pm
content: what kind of build issues and does it matter if it is a rebranded cem ?

author: PedroDaGr8
author_rank: Super Contributor
timestamp: April 18, 2014, 10:47:02 pm
content: Quote from: Flump on April 18, 2014, 10:29:34 pmWhere to start. How about this:https://www.eevblog.com/forum/testgear/teardown-extech-ex570-my-first-but-also-last-extech/One of the connectors fell off when he opened the meter, as in it basically wasn't soldered to the board. Other soldering issues plus the selector switch was already eating into the board.http://www.eevblog.com/2010/06/15/eevblog-94-near-death-multimeter-experience/Issue with Extech RC200http://www.eevblog.com/2010/07/11/eevblog-99-100-multimeter-shootout-extech-amprobe-bk-precision-ideal-uei-uni-t-part-1of2/issues with the board and attempted repairs.https://www.eevblog.com/forum/testgear/extech-ex330-quality-issue/Ex330 quality issues (ON THE REPLACEMENT! The first one was RMA'd and the replacement was bad too!)https://www.eevblog.com/forum/testgear/extech-mm570a-arrived-as-replacement-for-ex570-but-is-it-better/Extech sent him an EX570A to replace a bad older one. It had a BLOWN fuse out of the box and fingerprints inside the LCD. Likely an old demo model they sent him.I can keep going if you wish. How much is CEM and how much is Extech who knows exactly but it appears both have huge QC issues.I can find more if you wish.

author: dannyf
author_rank: Super Contributor
timestamp: April 18, 2014, 10:50:10 pm
content: QuoteI would argue that those LEDs are likely "overrated" - they were really <15ma max leds sold to you, unfortunately, as 22ma leds.QuoteA 22ma rated led would have a life span far greater than 15,000 hours at 15ma - assuming adequate cooling.

author: Flump
author_rank: Frequent Contributor
timestamp: April 18, 2014, 11:03:30 pm
content: maybe you should research more before turning people away from specific multimetersonly 1 of your links is pertinent to the ex330 and even that is not a HUGE build issue.I just had a look in mine and the soldering is fine.dave didn't notice any problems with the soldering in his ex330 when he did a review and internal look at itmaybe dave and I are blind, or maybe its not the HUGE issue you try to make out it is ?so are these HUGE build quality issues for the ex330 just founded on that one thread ?besides it was £20 new, I was not expecting Fluke quality.

author: dannyf
author_rank: Super Contributor
timestamp: April 18, 2014, 11:17:13 pm
content: QuoteIt is helpful in a discussion not to impute your opponents' "motive". If you disagree with their points of view, just lay out your arguments and let others be the judge.PedroDaGr8 simply provided her/his point of view. Even if her/his point of view is factually incorrect (I am not sure about that), that by and of itself doesn't mean s/he had the intent to exaggerate.Talk about the facts, don't talk about the individuals.

author: Flump
author_rank: Frequent Contributor
timestamp: April 18, 2014, 11:37:21 pm
content: I agree Danny and maybe i went a bit OTTand i apologise to you Pedro, no offence meantbut when i read your post it came across asyou just wanted to put down the meter because i bought one.

author: PedroDaGr8
author_rank: Super Contributor
timestamp: April 20, 2014, 02:24:02 am
content: Quote from: Flump on April 18, 2014, 11:37:21 pmIt wasn't at all an attack on you or your purchase. I'm sorry if you felt it was because I didn't intend it that way AT ALL. I was strictly commenting on the fact that Extech and CEM have huge issues with their quality control department. Does this mean every single meter that leaves their factory is a steaming pile of crap? Not at all. It just means that the end user has a higher chance of receiving a defective unit than they would going with another manufacturer. I'm glad to hear that your meter is good and I hope that it serves you well. I just have seen significantly more people burned by Extech than most other manufacturers (almost all by QC issues which should have been caught). The design quality of Extech meters range in quality from rubbish to quite good. This is something I actually don't have a problem with. They design to various price points. The lower end will be crap the upper end will be good. The designs of the upper end Extechs which are rebadged Brymen not CEM, are top notch. The issue is that the quality control isn't there and that lets down what is a great design.On the qc note. I do not recommend hp laptops to friends for similar issues. One of their worst designs the dv2000 series had a failure rate of around 25%. This still means three out of every four laptops had no issues at all. Meaning the vast majority had no issues. The problem is the buyer has a one in four chance of getting a pile o crap.Hopefully, this explains my position much more. Sorry again for you feeling like I was attacking you.

author: vladdrake
author_rank: Newbie
timestamp: July 25, 2014, 05:46:00 pm
content: hello everyone,i've been reading this forum for 3 days continuously and i find it really helpful on so many points !So i am considering buying one of these multimeters :the UT139C ;the UT61E ;or the Minipa ET-997 (http://www.dx.com/p/3-0-lcd-handheld-digital-multimeter-voltage-current-resistance-temperature-1-6f22-42269#.U9IzU_l_t4K), not sure about the quality of this one.They seem quite great for my purpose (rebuild sub ohm coils with an average of 0.8 ohm for ecigarette, test battery charge and some other basic house stuff), i'm a simple electronic hobbyist.But i have some questions before choosing, and i'm turning to you, the connoisseurs to help me. Which of these has best features (i think i don't really need a very accurate multimeter) ?For the moment my preference goes to the UT139C, it measures temperature, has good resolution and accuracy, it's true RMS, has NCV but it doesn't have a bar graph !Is the bar graph really useful, in what conditions ?Is the UT139C worth the extra bucks compared to the minipa ?And i would like to know if Franky sells better quality leads than those included with the UT139C ?I really thank you for your help in my decision.

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: July 25, 2014, 05:50:00 pm
content: Quote from: vladdrake on July 25, 2014, 05:46:00 pmYes, I dohttp://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=171162377470orhttp://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=171120395118

author: SeanB
author_rank: Super Contributor
timestamp: July 25, 2014, 05:59:06 pm
content: Buy the Brymen leads..........Do you still have those Fluke leads available Frankie? They are very nice as well.

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: July 25, 2014, 06:02:13 pm
content: Quote from: SeanB on July 25, 2014, 05:59:06 pmI might still have a pair of those Chinese Fluke TL175's, but can't be sure right now.

author: vladdrake
author_rank: Newbie
timestamp: July 26, 2014, 09:40:49 am
content: Thank you Franky for your prompt reply.Indeed the Brymen one seems to be really good !I'm looking for good quality leads with low resistance to calculate resistance under 1 ohm.Anybody to help me with the bar graph feature?

author: Yago
author_rank: Frequent Contributor
timestamp: July 26, 2014, 10:34:28 am
content: The LCD numerical display can not be read when there is a slowly changing level measured.Think of something similar to the turning signal on a car, the meter just reads numbers racing up then down.The bargraph simulates an analogue meter, and allows you to get some information from measuring such signal.

author: mariush
author_rank: Super Contributor
timestamp: July 26, 2014, 11:33:10 am
content: On UT61E, the numbers on the screen update 2 times a second (a bit slower than the average multimeter, which does 2.5 to 4 updates a second). The bargraph updates about 40 times a second.The bargraph allows you to see if what you measure is stable or not or if you have something that's active for short periods of time.For example, let's say you want to see if the tachometer wire of a fan works. You can connect the fan to about 5v, just enough to get the fan spinning slowly and you you connect the tach wire to that voltage through a pull up resistor. Now you can put the probes on tach wire and ground and you'll see that voltage on the digits most of the time, because it only updates twice a second, but on the bar graph you may see how the tach wire is pulled down to ground twice for each rotation (well, you'll see the bargraph moving more often than the digits)

author: vladdrake
author_rank: Newbie
timestamp: July 26, 2014, 01:54:07 pm
content: Ok thanks, so not really useful for me i think ^^

author: torr032
author_rank: Regular Contributor
timestamp: July 26, 2014, 04:04:07 pm
content: Bar graph comes in handy on the places where constant voltage should be expected, but for some reason it is not and that is causing the device to malfunction. Because of the slow update, numbers on the screen can't show if it is changing rapidly, so you will need a fast bargraph with enough segments at least like on the ut61e. And I would say numbers updates more like a 3 times per second.

author: vladdrake
author_rank: Newbie
timestamp: July 28, 2014, 05:02:56 am
content: I really thank you for the good explanation about what is a bar graph and what is it for.So which one of the three multimeters do you think is the best?

author: torr032
author_rank: Regular Contributor
timestamp: July 28, 2014, 11:26:28 am
content: Quote from: vladdrake on July 28, 2014, 05:02:56 amWhen I choose to buy some product, I always go to the most popular trading site in China, taobao.com and there I apply the best selling filter. If the chinese buy something the most in the land where competition is greater than in other countries then it must be good. Among better quality DMM's ut61E is the clear winner.

author: idpromnut
author_rank: Unknown
timestamp: July 28, 2014, 12:58:20 pm
content: This might come up a bit late, but the UNI-T 136C (with temperature) is fairly accurate, reasonably built and a decent "dicking around on the bench" meter. At CAD22$ shipped, it was a great temperature meter with the extra DMM features thrown in

author: larry42
author_rank: Regular Contributor
timestamp: July 31, 2014, 10:22:33 am
content: You're doing something wrong.A LED rated for 22mA (normal max, not Abs. Max) will not blow up at 22.1mA, unless it's faulty or other things are happening (such as an oscillating supply, current hogging etc) - are you driving these LEDs in series or parallel?You're doing something wrong, or your designing something wrong if you need more than 5% accuracy in current measurements for LEDs.Quote from: adrianf88 on April 18, 2014, 06:00:45 pm

author: larry42
author_rank: Regular Contributor
timestamp: July 31, 2014, 10:24:08 am
content: Quote from: torr032 on July 28, 2014, 11:26:28 amOf course that is an unstable feedback system - imagine if all the purchasers start to do that - rail to rail immediately...

author: onlooker
author_rank: Frequent Contributor
timestamp: July 31, 2014, 12:54:09 pm
content: From adrianf88's posts, I guess he is simply parallel all his 16 LEDs, which is,in general, a big no no.Such setup will explain why some LEDs will be burnt out earlier than others since as others had already pointed out LEDs are not really made equal even in the same batch.In fact, once some are gone, the others will be destroyed too due to the same CC is distributed to less number of LEDs.

author: torr032
author_rank: Regular Contributor
timestamp: August 01, 2014, 03:45:40 pm
content: Quote from: larry42 on July 31, 2014, 10:24:08 amWell I use it pretty often. Sometimes I buy item directly on taobao, sometimes I find the same on ebay. It works quite well and on taobao you are able to see buyers comments. Together with comments on amazon and with a little forums search you are able to distinct fake versus real ones reviews and get a picture of the product.