has anyone heard of UNI-T multimeters off ebay??? - Page 1
Forum section: electronics / beginners

author: doctorm
author_rank: Regular Contributor
timestamp: May 10, 2010, 05:47:09 am
content: hey guys. im just a newbie starting out in electronics for hobby. i have some college physics under my belt so im not totally in the dark lol.anyways, ive been looking for a multimeter on the internet and its been hard. i can probably go up to about $100 to spend on one but for the features i want, im having a hard time trying to find a good one to fit this.on ebay ive seen these supposedly great multimeters that are part of the UNI-T line. they seem to have great specs and are seeminly well prices for some models. but the thing is i can find anythign on them on the internet except for the home site and some very bad youtube videos.so my question is has anyone heard of or dealt with these multimeters? if so then is it a good multimeter? if not whats wrong with them?also is there any multimeters you guys can suggest to look at that are good. i know fluke is great and ive looked at all of them but i need some more options to look at that when i buy it, i wont have any problems. so ur advice would be greatly appreciated.

author: doctorm
author_rank: Regular Contributor
timestamp: May 10, 2010, 05:50:11 am
content: also just in case you are wondering, here are the specs im looking for in a multimeter i need:DCV: in the milivolts range to maybe 600 or moreACV: sameDC/AC Current: need something in micro range up to at least 10 AResistance: at least 20 Mohmscontinuity testdiodecapacitance: a good range at least. ive seen on go form 10 nf to 200 uf and then another to 1000uf so something like that i guess.so yeah thanks again.

author: EEVblog
author_rank: Unknown
timestamp: May 10, 2010, 06:02:19 am
content: See another thread in the Suggestion section, I'm doing a review of 5x $50 meters and 5x$100 meters shortly as part of a shootout.No Uni-T's though unfortunately.Dave.

author: Simon
author_rank: Unknown
timestamp: May 10, 2010, 06:41:06 am
content: if you can't find a half decent website of the manufacturer: be warned !

author: logictom
author_rank: Unknown
timestamp: May 10, 2010, 03:18:54 pm
content: Their websitethey sell them inMaplinsand have one over atSparkfunThere was some photos of the inside of one of the units, can't recall if it was here or not, but the general comments were along the lines of usual cheap Chinese multimeter.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 10, 2010, 04:25:00 pm
content: QuoteYes we have in Greece , for more than 14 years.UNI-T , has an extreme product range.I own one small one UT30D for 12 years, and I like it.Its my small one of the many , that stays always at the tool box ,and I measure mostly Mains 220V with it.Even the continuity Beep are fast enough to satisfy DaveYesterday ordered and the UNI-T 15C ( hand held tester).The most worthy tip that I have for you , get the best UNI-T that you can afford.Even if the company looks honest, the higher quality always goes with the price level.Yesterday I had the chance to play ( Test ) with an very old Metex (US + GER) patent ..The display had a terrible slow response and the numbers was just visible.The Beeper was even slower than ProS Kit DMM ( 18 years old ).And the selector, was produce an clicking sound , like to was an fake DMM Kids Toy.My opinion are that medium priced UNIT-T models, are very honest for their price.

author: Simon
author_rank: Unknown
timestamp: May 10, 2010, 04:41:24 pm
content: Quote from: logictom on May 10, 2010, 03:18:54 pmMaplin sells them ? I rest my case !

author: logictom
author_rank: Unknown
timestamp: May 10, 2010, 04:48:36 pm
content: Quote from: Simon on May 10, 2010, 04:41:24 pmlol, yeah I was tempted to buy one from Sparkfun and thought I would look for somewhere over here to save on the P&P and import. Once I found it in Maplin I started looking at other meters. Ended up with the 87V

author: Simon
author_rank: Unknown
timestamp: May 10, 2010, 04:53:46 pm
content: I would not touch anything from maplin other than basic materials and parts, I've seen too many over priced and/or horrible quality products to know

author: saturation
author_rank: Super Contributor
timestamp: May 10, 2010, 09:52:42 pm
content: Uni-T is another equipment maker, but not with the reputation of the some of the established Asian players like Instek.http://www.uni-trend.com/factory.htmlhttp://www.gwinstek.com/en/brand.aspxI have a better sense about gear from Taiwan, they are overall better designed, built and use quality parts. The problem with spec sheets is can you be sure its really that good? So, you need to have a brand reputation to earn enough trust among consumers to believe the spec sheet.

author: doctorm
author_rank: Regular Contributor
timestamp: May 11, 2010, 02:53:41 am
content: hey thanks everyone for the replies.hey while i was ebay i also came across these two multimeters. i think i heard of Protek before i guess but i cant remeber bc of just getting out of school lolanyone know anything about the two below?http://www.protektest.com/ProdInfo.asp?prodId=608http://cgi.ebay.com/Protek-6500-50-000-count-True-rms-DMM-/360260119445?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item53e12d2b95p.s. so excited about the multimeter shootout!!!

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 11, 2010, 11:10:32 am
content: The first of your link's , at the top of the page says clearly*** THIS PRODUCT IS OBSOLETE ***It looks that you are in a harry,and you do not process the information that you get, correctly .The UNIT-T its a good balance of value for money.Just select the best model that you can buy of those , and compare it with all the others.If you find a better one at the same value , just get the better one.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 11, 2010, 11:38:10 am
content: Additionally check the users manual before you buy anything.About looking for safety standards .Just download the manual of my little UT30D , and here it is ..

author: saturation
author_rank: Super Contributor
timestamp: May 11, 2010, 02:47:04 pm
content: OBSOLETE products are not necessarily bad, it just often means they stop production. For many uses an obsolete good model such as a Fluke often can outperform current lesser brand DMM anyday.

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 01, 2010, 07:45:10 pm
content: i just ordered a Uni-T UT70B from ebay. I'll take a blind shoot on it for about $70. Lets see if i have a hitThanx guys for info here.

author: saturation
author_rank: Super Contributor
timestamp: June 01, 2010, 08:24:24 pm
content: Review it for us please, when you get it. Enjoy.Quote from: shafri on June 01, 2010, 07:45:10 pm

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: June 01, 2010, 10:58:51 pm
content: The UNI-T, had start even at the " Financial Crisis time " in 2010 , to blast the market with "quality at low price " .Even more "New" fresh products, with fresh technology in them .. are ready to enter in the market .The UNI-T Chinese site are on continues reconstruction .. The international site its not updated yet .New portable Oscillators , and DDM cables are ready to go ..Even the tester that I got , are so advanced .... that by demonstrating it , at one Greek forum , at the fellow electricians , an true panic started about getting one for them too.Voltage meter + Led voltage reading + polarity + continuity tester + phase direction (motors) + light torch + single probe phase detector ... got it directly from China for 23EUR , and found it to be sold in Greece for just 32EUR with VAT ..Thats an amazing pricing , and they will get enormous market share .. I am starting to believe that the year 2010 , its the year that the UNI-T, it will start to shine for good.Additionally :Any one working with Mains 220 , its recommended first to use such testers before using an DMM to take an more accurate measurement ..Pictures maestro ..

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: June 01, 2010, 11:00:28 pm
content: second wave ..

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: June 04, 2010, 06:00:57 pm
content: Quote from: shafri on June 04, 2010, 03:28:45 pmDo not expect from me to search the deferences, and spot them , thats your job ..so to inform us.

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 05, 2010, 12:49:14 am
content: i've made a post on this inhttps://www.eevblog.com/forum/index.php?topic=500.15this is just an echo from there:1) greater uA range at low side (200uA on UT71A compared to 400uA on UT70B)2) USB connection compared to RS232 (not sure whats it for, no review on this online, i hope its for sending data to PC)3) greater count accuracy, 3999 for 70B, 20000 for 71A4) with carrying case5) 71A looks more pro and sexy! oh yeah baby!and all this is just for $20 addition, i think its worth it.my only concern with this "new technology" DMM is that reading/update speed. i dont understand why more expensive DMM's are very slow at even continuity check where my $20 can do that in split second. similar to other V and A reading too.

author: EEVblog
author_rank: Unknown
timestamp: June 05, 2010, 03:23:03 am
content: I'm getting quite few calls to include the Uni-T in the $100 shootout.But which one. I haven't really looked at it yet, but the website shows the 71A through E! and the other models have A though D or E as well!It's also hard to compare a cheap name (probably fragile) $100 20,000 count 0.1% meter to a 6000 count 0.5% rugged industrial meter.The UT61x series looks like the closest match with the other meters I think, but they are significantly cheaper than the others.No contacts at Uni-T, so don't know if I can get one in time. Unless I fork out $100 of my own money that is. Can always resell it afterwards I guess, if I don't smash it :->Dave.

author: EEVblog
author_rank: Unknown
timestamp: June 05, 2010, 02:01:09 pm
content: What the hell is going on with Uni-T meter pricing?The UT61 series is the closest to the other $100 meters in terms of functionality, but the UT61D is more expensive ($72) than the much better speced UT61E at $65.The cheaper E model is 0.1% vs 0.5% and 22000 count vs 6000 count.Both TRMS and CAT4Looks like the E model drops the temperature and backlight to gain the extra performance for less $And in the catalog the photo does not show the E model having a 5 digit display!The other ranges of meters seem just as weird.Looks like they have so many damn models they have no idea what they are doing!Would people rather see the E or D model review? The 71 series is just too different to the other models in the shootout I think.Dave.

author: Unknown
author_rank: Unknown
timestamp: June 05, 2010, 03:05:23 pm
content: No idea about what Uni-T's marketing people are thinking, but I'd definitely take the E model if I had to choose. I consider temperature of limited use, and backlight on a battery-powered meter usually isn't that useful since it either turns off in a few seconds or sucks down the batteries. I'm sure people often having to work in dark spots would disagree, but most of my electronics work takes place on a well-lit bench.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: June 05, 2010, 04:01:34 pm
content: Quote from: EEVblog on June 05, 2010, 02:01:09 pmThats the only downsize of them , their model listings, it does cause confusion..Thats why you have to individually check its product manual ( pdf ) ..

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: June 05, 2010, 04:14:20 pm
content: Quote from: alm on June 05, 2010, 03:05:23 pmYes we do , most industrial installations,was not build by having in mind the " easy " of service or maintenance.Lots of metallic cabinets , with no light , or even worst .. with no free access on them.Any meter with back-light , expands the potentials for "out-bench" usage ...

author: Unknown
author_rank: Unknown
timestamp: June 05, 2010, 04:48:44 pm
content: That's why they have all those different models, to please everyone.I'm sure someone who works in an industrial environment has very different requirements. For example, I've always considered the hold button (not auto hold) to be quite silly. The only time that I want to hold a reading is if I want to synchronize multiple meters, but I can't press four different hold buttons at the same time, so I use the external trigger feature. But for people who have to take measurements in inaccessible places where they can't read the display at the same time as connecting the probes to the circuit under test, this might be a very important feature. It's probably hard to please both crowds at the same time.

author: EEVblog
author_rank: Unknown
timestamp: June 05, 2010, 11:36:44 pm
content: If it was my money I'd probably get the E model over the D for the better accuracy and counts, temp and backlight wouldn't matter as much in my case.But as for the shootout, all the other meters are 0.5% and 6000 count, so the D model is the most comparable in that respect. If I chose the E model I'd have to try and explain the pros and cons of 20000 count and 0.1%+counts vs 6000 count 0.5% in the other models etc.So I'll probably just order the 61D model from ebay I think. That's a 6 meter shootout now.Dave.

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 06, 2010, 08:38:38 am
content: one more thing i got confused... why they show 20000 count accuracy, what does it mean? not like 29999? or 2999 or 9999?whats the difference?

author: Unknown
author_rank: Unknown
timestamp: June 06, 2010, 09:06:55 am
content: It's probably 0 - 19999 (20000 counts). Can't imagine them spending the extra $0.01 on the segments just to display 20.000.

author: EEVblog
author_rank: Unknown
timestamp: June 06, 2010, 11:55:11 am
content: Quote from: shafri on June 06, 2010, 08:38:38 am20000 count means 1999910000 count means 99992000 count means 19996000 count means 5999 etcDave.

author: cybergibbons
author_rank: Frequent Contributor
timestamp: June 06, 2010, 12:25:09 pm
content: If the meter is 2000, 20000 etc. count, then they are normally limited by the LCD (or the LCD is matched to the ADC). A 3000,5000,6000,8000 etc. has the full digit in the display, but it just can't use it.Quite a few of the Unitrend meters have a much higher count than the accuracy warrants though.

author: Fernando
author_rank: Newbie
timestamp: June 09, 2010, 07:55:05 pm
content: I've got a UNI-T 60E, I got it locally (Chile) for something like US$80, it's rugged I have dropped it from the bench several times.Continuity beep is fast and loud but not latched. It's based on a FS9721-LP3 IC, from the Chinese Fortune IC.BTW GW-Instek sells this same meter in other colours under the GDM-396 model.One of the things that bugs me of my meter is that the back light button is the same as the Hold button (no auto hold), and the hold button function is useless, if I'm having trouble positioning the probes I won't bother on pressing a button.

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 14, 2010, 08:52:29 pm
content: my $90 baby has arrived. 1 week delivery hongkong-malaysia excluding negotiation to change model UT70B to UT71A. quick test indicates:i like:1) build quality, design and weight, a lil bit heavy compared to my cheapo one, got the impression that its built for quality. but others opinion may differ.2) accessories: box,bag,cd, aligator clips,manual... a pen gift from the seller, not so good in quality though (the pen), but its just a humble gift that i never ask for or expected from the seller, thanx seller!.3) lot of decimals compared to my older DMM (4 decimals point)4) tolerable reading speed. for the precision it gives, i think its quite fast... compared to DMMs Dave has reviewed.5) datalogging in PC through "infrared" usb cable (one of a kind that i never saw before, its like 2 eye (LED) at the end of USB cable, i think 1 led to send data, and another one to receive data). but its like 1 reading/sec update rate? very slow. ok for me since i never have this feature before, but for pro, i think it will be useless. can save in excel format. got to dig more into this if it can update at faster rate reading.6) white backlight (setupable to change the auto off timing)7) beeper sound quite louder than my older DMM. i dont really mind, but i prefer if it could be lowered (so to avoid disturbance to my wife/children in the next room) but i dont think its loud enuf to do that.dont wiggles when on its stand (or like Kiriakos termed it as dancing like a boat). basically it has solved all the issues Dave mentioned about the bail problem. It has an angled inclination on the bottom back casing that will lay flat to the surface to make it more stable. It has protuding rubber on the back at each corner so when we lay it on the surface facing up, it will hold and grip in that position.i dont like:1) slow continuity check. as Dave called it... sucks! thumb down. But i think its workable, its like you have to stay shorted for about half a second to hear the beep, so running slowly on chips leg to find continuity will make it work. i think i can get used to it, its just a matter of time. i've done some simple sweeping test.2) too long probe cables (around 120cm), but thats just me. will be harder to work in confined space just as i usually did (in my "small lab")3) protruding buttons and knob. When fall, this knob will be potentially got damage if it hits first on the ground. But thats just minor, its just becoz Dave has mentioned about this problem b4. But i will take care of it, if it falls, i will put the blame on me for not taking care of my baby properly4) No OFF Button! we have to rotate the knob to OFF position! This is what i really hate most!i havent make a thourough testing on reading though, but from early test, i can say, i have no issue with the reading (DCV, ACV, Ohm), instead being happier coz it shows more decimals point than what i used to have.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: June 14, 2010, 09:20:49 pm
content: You have right, this pen its not an worthy one ..The most like able point of detail , are the anti skate bubbles at the bottom of it .As design its a lollipop ... Nice tool ..

author: cybergibbons
author_rank: Frequent Contributor
timestamp: June 15, 2010, 04:59:57 pm
content: I've just picked up a UT-71D, which is rebadged as a Tenma 72-7732 - which means that the case is orange instead of red.First impressions:* Strong case + display cover* Battery compartment internals very very thin, quite hard to get battery in.* Backlight very bright and even.* Display good and clear* Rotary switch has a good feel to it.* Beeping warning if probe in A/mA socket and you set the mode to anything other than current.* Everything seems to work OK* Frequency mode is not very sensitive - needs quite a large amplitude to work.* Stand is stable, but leaves the meter at a very low angle (display still readable). Would snap off if dropped with it extended.* Continuity check is slow, but latches so none of the horrible scratching noise.* Big concern is the warning in the manual to not apply voltage when using the temperature mode - I could see myself leaving probes connected and switching to this range by accident.* A neat feature (similar to some Flukes) is the ability to switch it into 4000 count mode by pressing the blue button whilst turning it on.I've not tried the USB connectivity - I did however notice that there are two windows on the back for connectivity, but only one on the cable. Maybe one is used to detect the presence of the cable.

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 15, 2010, 05:21:11 pm
content: mine beep too when probes in mAuA or A and mode is different from it. for me, the rotary switch is a lil bit hard, but ok. so we have the same slow continuity check issue, i guess thats just how it purposedly design. but i still love the fast respond of my older DMM, even if its not latched/scratchy sound.only thing concerns me is that, i just found out when we are in continuity check mode and we connect the probes to +ve and -ve of a battery.. it will beep, its like shorted. is it normal? my older DMM dont do that

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: June 15, 2010, 07:35:11 pm
content: Quote from: shafri on June 15, 2010, 05:21:11 pmI do not do comments, about abnormal usage of DMM's ... simple as that .

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 16, 2010, 01:47:20 pm
content: another peculiar behaviour for Unit-T 71A. is when we switch to mV from another mode (after a while) except OFF, it will show some deviation when the probes is not connected or open circuit. sometime its -90mV -12mV etc. sometime it will be increasing in magnitude slowly in time. similar to ACV mode, at first, it will show some deviation, but it will converge to zero. for the mV, it will return to zero when 1) we short the probes (but if we release, it will deviate again) and 2) switch OFF (for a while, around 5-10 secs) and switch ON directly to mV. is this normal? or abnormal?

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: June 16, 2010, 02:09:14 pm
content: Quote from: cybergibbons on June 16, 2010, 02:02:11 pmExplain what ?That every range has an specific impedance ?I think that you got an DMM by far ahead from you skills level .Returning it back, sounds as an reasonable idea ..And get something simple ..

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: June 16, 2010, 02:15:40 pm
content: Quote from: shafri on June 16, 2010, 01:47:20 pmSuper normal ... at every free play of the leads in mV (range) , there is always some mV displayed ..As long any time that you cross the leads , the value fall to zero , the meter called healthy - calibrated.I have write all this over and over at the Fluke 87-5 thread ... why no one reads them !!https://www.eevblog.com/forum/index.php?topic=354.0Post number 10

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 16, 2010, 02:35:10 pm
content: sorry Kiriakos, maybe i missed it. but i dont have issue with uA and mA as cyber did. it will always showing zero at disconnected probes, connected but opened, and short circuited. maybe it something to do with floating input (tristated?) port in some chip inside that will read random level? or some capacitor is charging or discharging inside, since i picked up a consistent increment in mV open circuit reading. but still, i dont know the exact explanation.

author: cybergibbons
author_rank: Frequent Contributor
timestamp: June 16, 2010, 02:59:38 pm
content: I just had a whinge up above at the burden voltage on the uA range on the meter and then deleted it.It seems that it is 0.5mV/uA, which actually isn't too far out of the ordinary. It's just the fact it's a 40k count meter meants that 4000uA * 0.5mV = 2V!Andrew

author: Unknown
author_rank: Unknown
timestamp: June 16, 2010, 03:56:44 pm
content: Quote from: Kiriakos-GR on June 16, 2010, 02:09:14 pmYou wanted to prove the statement 'There are no stupid questions, just stupid answers'?Quote from: shafri on June 16, 2010, 02:35:10 pmThe impedance of the ideal voltmeter is infinite (10Mohm for most handhelds). The impedance of an ideal ammeter has a zero impedance (a few hundred milliohm to a few kiloohms in most meters). The leads form a loop which can pick up electric and magnetic fields, and have a parasitic capacitance (so does the input circuit of the meter). If your meter has capacitance ranges with resolution down to the sub-nF level, you'll notice a non-zero reading with the leads plugged in (not connected), which changes depending on their distance. This capacitor is charged by the signals picked up by the leads, and because the resistance in parallel is only 10Mohm, it's discharged slowly. In other words, for a 10mV signal in 10Mohm impedance, you only need to induce 2nA.On the amps range, the impedance is much lower, a 2nA induced current will never register on most DMM's.So can you use the voltage range as sensitive ammeter? Yes, as long as you can live with the burden voltage of 10V/uA.

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 16, 2010, 04:40:47 pm
content: what?! what burden? anyway nvm. some curiosity that makes me take apart. i found out this UT71A is a one eyed pirate. from outside its like 2 eyed usb comm (transmit and receive), but actually, its only transmit eye that exist (as in the 2nd picture). probing the IR out with some sensor indicating its transmitting data at 1.5 reading/sec (ie 3 readings in every 2 seconds). so i guess there is no way to boost the datarate since its only a one eyed pirate! up to my knowledge only, someone else may dig deeper, who knows.1) batt compartment, quite nice for me.2) the one eyed pirate of the carrebian3) the pcb (notice a jumper and trim pot there)4) data received by PC (tabulated and graphical, can save as excel format and bmp for graph)

author: cybergibbons
author_rank: Frequent Contributor
timestamp: June 16, 2010, 05:22:51 pm
content: Quote from: Kiriakos-GR on June 16, 2010, 02:09:14 pmIt is however, a very, very big jump - from almost 0 to 500 ohms. It means that if you are measuring 4000uA on the uA range and jump to the mA range, you can see big differences. All the meters I've had before have been more distinct between the uA and mA ranges. On a 2000 count meter with a range of 20uA and 2mA, the highest reading on 20uA is only twice the lowest on the 2mA.With this meter the mA range can show down to 1uA, and the uA range up to 2mA - that's a factor of 1000.Not every range has a specific impedance either - both manual ranging meters here have the same shunt resistor.

author: Unknown
author_rank: Unknown
timestamp: June 16, 2010, 09:20:04 pm
content: Quote from: shafri on June 16, 2010, 04:49:08 pmThey probably mean capacitors in the DUT, eg. a CRT. Not sure what they mean with high voltage, the 1kV or so according the electrical code, or what an average consumer considers high voltage (>50V). It might indicate a limited voltage tolerance of the capacitance range. I wouldn't read too much into those warnings, since they're probably written by lawyers. Just use common sense. It's good practice to make sure capacitors are discharged before touching something.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: June 16, 2010, 11:44:32 pm
content: Quote from: shafri on June 16, 2010, 04:49:08 pmIts not waterproof , thats all about the " indoor " ..

author: cybergibbons
author_rank: Frequent Contributor
timestamp: June 17, 2010, 07:02:08 am
content: The internals of mine are almost exactly the same - just the A sticker says D. That means that I am the "one eyed pirate" as well.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: June 17, 2010, 08:37:19 am
content: Quote from: cybergibbons on June 17, 2010, 07:02:08 amIf you feel miserable about it ... Get the Gossen MetraWatt ... 499$ plus another 499$ for the communication module .

author: orbiter
author_rank: Frequent Contributor
timestamp: June 17, 2010, 04:48:15 pm
content: I've got a similar, if not the same meter. Well it looks the same and has very very similar internals, except it carries the Voltcraft name. I posted the specs so anyone interested can check it out. Seems like a pretty decent meter to me and I can't fault it yet. Cost me £118. It's not the top of the Voltcraft meter range but it's not far off.

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 17, 2010, 05:54:18 pm
content: yup! this one is blonde. the Unit-T one is the red head! but... they are both sexy!seem closer to 71B-E coz it has temp reading. not sure if this one got IR USB Con. The most visible difference is the probes.another clone war has begun. blind we are... if this **** we cannot see (forgot the quote from master yoda)

author: orbiter
author_rank: Frequent Contributor
timestamp: June 17, 2010, 06:38:04 pm
content: Quote from: shafri on June 17, 2010, 05:54:18 pmYes shafri mine has the IR pickup too, and as you noticed a temperature sensor which does seem pretty accurate. The only visible difference on the board though is this part for True RMS-to-DC Conversion..Regarding the probes. Mine both state CAT III 1000V

author: orbiter
author_rank: Frequent Contributor
timestamp: June 17, 2010, 07:13:13 pm
content: Quote from: shafri on June 17, 2010, 06:54:24 pmI checked out the datasheet for these parts and found that both do the same job (True RMS devices) As far as I can tell the different part numbers relate to the accuracy of the component. The way I read it is... If you have the AD636K IC chip, It's more accurate than the can?http://www.datasheetcatalog.org/datasheet/analogdevices/AD636JH.pdf

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: June 17, 2010, 07:27:15 pm
content: Quote from: shafri on June 17, 2010, 05:54:18 pmReally ?Quote from: shafri on June 17, 2010, 05:54:18 pmReally ?( 20A)I am going out to celebrate the victory of the National team against Nigeria ..

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 17, 2010, 07:36:38 pm
content: checked mine, its ES636http://www.datasheetcatalog.org/datasheet/CyrustekCo/mXutxrv.pdfi dont really care much of the accuracy, they should pretty close, for the human to comprehend.

author: armandas
author_rank: Frequent Contributor
timestamp: June 17, 2010, 09:29:55 pm
content: Quote from: shafri on June 17, 2010, 06:54:24 pmIf that makes you feel any better, you can switch it off by rotating the dial clockwise.

author: Unknown
author_rank: Unknown
timestamp: June 17, 2010, 10:54:17 pm
content: Quote from: shafri on June 17, 2010, 09:41:27 pmNote that you will void the IEC 61010 CAT ratings by doing this. The battery is often at line potential, and drilling a hole will decrease the protection against arcing and blasts.Quote from: shafri on June 17, 2010, 06:05:14 pmIt's common for equipment to be rated for both CAT IV 600V and CAT III 1000V. That means that you can use it on circuits up to 600V in CAT IV environments, but up to 1000V in CAT III and lower environments. The transient requirements for CAT IV 600V are actually stricter, so it's quite easy to pass CAT III 1000V once you've passed that one.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: June 17, 2010, 10:54:27 pm
content: Quote from: shafri on June 17, 2010, 09:41:27 pmRemove the battery for 5 minutes , so to find out .. simple solutions .

author: EEVblog
author_rank: Unknown
timestamp: June 18, 2010, 12:48:41 am
content: My Uni-T arrived from Hong Kong in the usual HK wrapping style!http://www.eevblog.com/images/misc/Uni-TmeterPackage.jpgNote the product description!Dave.

author: EEVblog
author_rank: Unknown
timestamp: June 18, 2010, 02:36:45 am
content: Quote from: shafri on June 18, 2010, 01:17:58 amIt was marked as Gift.In Australia we only get charged duty on anything over $1000.Dave.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: June 18, 2010, 01:03:45 pm
content: Do not zap it with high voltage, before even testing it !!

author: orbiter
author_rank: Frequent Contributor
timestamp: June 18, 2010, 01:49:39 pm
content: Quote from: EEVblog on June 18, 2010, 02:36:45 amYour quite lucky there then Dave in that regard. In the UK I don't think it will be too long before we're being taxed just for breathing in

author: ElektroQuark
author_rank: Unknown
timestamp: June 18, 2010, 02:07:44 pm
content: In Spain it has been changed recently to 22€, shipping cost included!

author: marianoapp
author_rank: Regular Contributor
timestamp: June 18, 2010, 04:49:35 pm
content: in Argentina you can import a maximum of USD 25 per year, anything above that and you have to pay 50% of the value of the product in customs taxes.. [yes, its not a typo.. 50%]

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 26, 2010, 02:50:19 am
content: an update of the UT71A... some peculiarity when reading capacitance. so far what i can conclude, i cannot rely on the capacitance reading yet. need a thourough testing later when i got time. i found out that i still use my older DMM to do some job as it can still give me satisfactory/fast reading (V and A). for V and A, the UT71A is just too accurate for my need. put it back in the bag and box, so it will not collect dust, my poor sweet baby! think i'm going to use it when i need the V and A reading simultaneously side by side to my older DMM.

author: MyZirconia
author_rank: Contributor
timestamp: June 26, 2010, 05:10:15 am
content: Hmmmm!shafri thats looks like its a UNI-T problem with capacitance measurements because my Uni-T UT60E cannot measure capacitors any good (compared to my FLUKE 198)for instance it cant measure capacitors greater than 100uF i have tried several caps.othewise my UT60E seems to work, i havent tried it so much but i will do some more comparing against my FLUKE 198//Magnus

author: cybergibbons
author_rank: Frequent Contributor
timestamp: June 26, 2010, 07:34:07 am
content: Does yours switch to a lower count number if you turn it on with the blue button held down?

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 26, 2010, 05:24:08 pm
content: Quote from: cybergibbons on June 26, 2010, 07:34:07 amhow to tell the difference? it seem to change nothing if press hold blue button while ON, yet its in manual. i think its one of the stupid thing for this Uni-T. hold the blue button longer, it will beep continuosly.

author: cybergibbons
author_rank: Frequent Contributor
timestamp: June 28, 2010, 09:03:30 am
content: Mine loses the end digit, going from a 40,000 to 4,000 count meter.

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 28, 2010, 10:05:03 am
content: which mode? any mode?

author: cybergibbons
author_rank: Frequent Contributor
timestamp: June 28, 2010, 10:34:25 am
content: All modes, yes.

author: Mechatrommer
author_rank: Super Contributor
timestamp: July 01, 2010, 01:05:53 pm
content: another update. the reduced digit count feature will read quicker than the normal digit count. so its usefull when you need rapid answer. if only there is setup to make the reduced mode as a default without pressing the blue button on startup.the min max display is another valueable feature, recommended to get DMM with this. it can detect the V or A spike/pulse so quickly that normal/cheap DMM wont show. at least for me and my Uni-T. I think i'm going to miss it if i dont have it.

author: d3javu
author_rank: Regular Contributor
timestamp: October 12, 2010, 05:27:34 am
content: Shafri, do you have any plan to take it apart?

author: d3javu
author_rank: Regular Contributor
timestamp: October 12, 2010, 04:49:29 pm
content: Oh, seems like i've jumped just the particular page your pictures are on. my bad. Yea seen his review on D version which has true rms. Yea, i would love to take it apart, see if i can get my hands on a good camera.

author: BBK
author_rank: Newbie
timestamp: April 28, 2011, 09:17:05 pm
content: Hi,through Daves 100$ Multimeter Test I intent on the Uni-T multimeters.May someone can help me? The problem is I need one with temperature measurementfor a good price.Should I take the 61C (53$ on ebay)? 71B (120 $ on ebay)?Or another model?Im a noob in electric

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: April 28, 2011, 09:27:10 pm
content: UNI-T can be found easily locally in EU and USA .By getting it from a near by shop in your area , you will also have an warranty coverage.About temperature on DMM's , the acceptable accuracy is 1% .Check the users manual for specs, so to get the proper one .

author: Mechatrommer
author_rank: Super Contributor
timestamp: July 08, 2011, 10:37:29 pm
content: added to my collection.1) Uni-T UT202 Clamp Meter ~USD29 - choosen because lower ACA range (for home usage), down to 2A in 1mA max resolution. got temperature meter.2) Unit-T UT21B Voltage Detector ~USD17 - choosen because i just curious (from same seller of UT202), got beep and led blink. it seems i still prefer my test pen if wire can be contacted. i was hoping it can detect live wire behind wall, but cant.the family become larger

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: July 08, 2011, 11:14:21 pm
content: Quote from: Mechatrommer on July 08, 2011, 10:37:29 pmI know where you are getting it, you wish to become electrician, and get all the money..Nice staff , but I dislike the look of this modern tester, no mater the brand who made them.They look more like an accessory from the project Sagan than tools.About the clamp, just by looking at it, I feel like be home.The air smells like three phases and AC all over the place.

author: Mechatrommer
author_rank: Super Contributor
timestamp: July 08, 2011, 11:23:52 pm
content: i want to save money (electric bill) by looking which appliances in my home use much electricity. so i can control their usage. i've teared down the voltage tester, later i'll see if i can lower the voltage sensor or increase the distance range to detect wire behind wall. diy should be easy from the look, ive marked all the small components label, if someone can tell what 6 pin tssop mcu with label 0662 on it i will be grateful.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: July 09, 2011, 12:44:14 am
content: Quote from: Mechatrommer on July 08, 2011, 11:23:52 pmOk here it is, Its made in Germany from Volltronic at 1990, with adjustable detection range,but no buzzer. ( The maker does not look alive in the web)Its specialized for walls , that's why it has special " antenna " or better said " coil ".

author: Unknown
author_rank: Unknown
timestamp: July 09, 2011, 02:36:35 pm
content: Quote from: Kiriakos-GR on July 09, 2011, 12:44:14 amI have something similar. It can detected both metal and AC wires, and has adjustable sensitivity. Was fairly cheap if I remember correctly. I only used it for detecting metal, sensitivity of the AC detection didn't seem very good.I don't understand the point of clamp meter for residential electronics. Live and neutral are usually in one cable, so where do you put your clamp? If you have to insert a modified extension cord, you have to break the circuit anyway, so I don't see the point of a clamp. Maybe an electrician can elaborate?How do you determine real power from separate current and voltage measurements? Do you measure the power factor somehow? The normal way is to average the instantaneous product of current and voltage, but that would require measuring both with the same instrument.Those Kill-A-Watt type devices that go between socket and plug are probably cheaper, more convenient and more accurate for domestic and office applications.

author: Zero999
author_rank: Super Contributor
timestamp: July 09, 2011, 02:46:02 pm
content: Clam meters work at higher currents and I can measure the current consumption of everything in my house, just by putting the clamp over the live wire where the power enters the building.

author: Mechatrommer
author_rank: Super Contributor
timestamp: July 09, 2011, 04:08:40 pm
content: here's my reading/record last night1) air cond (compressor on) = 3.86A2) water pump = 1.73A3) refrigerator = 0.9A4) water heater = 3A (0.13 during standby)i checked last night live wire coming into my house, it measured 2.6A when water pump is off. but when turned on, the reading is 4.3A. so they add up. but i'm not electrician and i dont have clue on PF effect on usage (KWh). so maybe someone can advise me. i just roughly estimate using P = VI (rms)

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: July 09, 2011, 06:56:19 pm
content: Quote from: alm on July 09, 2011, 02:36:35 pmMy next project will be " a modified extension cord "Actually It will look like a small accessory.There is some available but only for the 120V US type plugs.Quote from: alm on July 09, 2011, 02:36:35 pmIf there is AC voltage unbalance present, the lights in your home they will start dancing.If they do not flicker, you do have stable input of mains.And so the Ampere is your only unknown factor.Quote from: alm on July 09, 2011, 02:36:35 pmMy opinion is that they are unworthy toys.How can you tell about their accuracy ?The classic trusted Ampere clamp, does not lie that easy, and you can verify it, even by connecting one good DMM in line with the load.Those tips are for professionals only .

author: jahonen
author_rank: Super Contributor
timestamp: July 09, 2011, 08:25:23 pm
content: Quote from: Kiriakos-GR on July 09, 2011, 06:56:19 pmI believe he means a load which measures like this on an oscilloscope with Fluke 80i-110s (current) and DP120 (voltage):Here, we have RMS voltage (yellow trace) of 240 VAC, RMS Current (green trace) of 1.151A, thus apparent power is S = 276.2 VA, but real power (average of instantaneous power in purple) delivered to the load is just 179.6 watts. That gives power factor of about 0.65. How can you tell the real power by just measuring the RMS Current and voltages, if your load is nonlinear (like in this case)?Regards,Janne

author: Unknown
author_rank: Unknown
timestamp: July 09, 2011, 09:33:35 pm
content: Quote from: Kiriakos-GR on July 09, 2011, 06:56:19 pmSo the advantage is just a higher current capacity and slightly easier connection (one clamp as opposed to two isolated leads). You could also make an adapter with two safety banana plugs to put a DMM in series. I believe I've even seen them for sale.Quote from: Kiriakos-GR on July 09, 2011, 06:56:19 pmOh, they're certainly not metrology class tools, or even professional tools. But neither is a $30 Uni-T clamp. The error due to power factor is likely to be larger than the error in the consumer toys due to lack of calibration, especially for the switching power supplies without power factor correction. For a proper measurement I would get my scope, voltage probe and current probe out, and do the instantaneous multiplication and calculate the RMS of the product. But that's just much more complex.Quote from: jahonen on July 09, 2011, 08:25:23 pmExactly. Few loads are linear these days, except for maybe heaters (as long as they don't do PWM). A transformer with large smoothing capacitors will only draw current at the peaks of the voltage waveform. A motor tends to be inductive, which introduces a phase shift between voltage and current. The perfect inductor draws current and drops voltage, but draws no real power, only reactive power, due to the ninety degree phase shift between voltage and current, so PF = cos(phi) = 0.The good consumer power meters actually do the same as what Janne shows, and perform OK with non-linear loads. I believe there are also professional versions of these power meters available, but I've never bothered to look.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: July 09, 2011, 10:09:41 pm
content: Quote from: alm on July 09, 2011, 09:33:35 pmThe design is simple, two sockets with separate isolated leads that run throw hard plastic pipes.( actually Teflon)The phase cable runs solo, and in the second pipe, there is together neutral and earth.I have the Teflon pipes, just need to drill the center holes.The similar design that I have see for the American plugs, they have even two positions ( holes) so to add the camp on,the one called X1 and the second X10, and so you can use even one less sensitive clamp,So to measure low amperes.Quote from: alm on July 09, 2011, 09:33:35 pmUNI-T is not responsible for the low price of the AC clamps.... they are cheap to build, always was.I got shocked few months back, when I found the price of the AC/DC clamps, that it is 10 times more than the AC ones.And the general rule are that electricians can do their work with out very expensive tools,I must have lost my way, because I had break the general rule ...

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: July 09, 2011, 10:51:40 pm
content: Quote from: alm on July 09, 2011, 02:36:35 pmI do not determine real power, this is the job of an engineer electrician.Personally I am licensed only for maintenance up to 200KW installations.And mainly I care for the health of the power lines and the protection circuitry in the power boards.I do not have to speculate about power factors, I am aware from the beginning that all my loads are motors.And even the clamp most of the times works as diagnostic tool, about comparing the Amperes in three phases motors,if you detect an major anomaly, you just replace the motor.Another practical example of where you use the clamp, is on motors that they connect with tension belts.If you had adjust the tension belts correctly , the motor will operate with the nominal power.Now days with the UPS devices, and the inverters, the electricians does need more high-tech tools.The AC/DC clamp becomes more and more as " must have " tool.I just wish that UNI-T will move forward, and offer an similar tool like the Fluke i400 clamp,in a more sweet price.As they use to do with their DMM.

author: Mechatrommer
author_rank: Super Contributor
timestamp: July 10, 2011, 03:22:02 am
content: Quote from: Kiriakos-GR on July 09, 2011, 06:56:19 pmyou mean like picture below? it works in any VAC that you put it in, be it 240V or 120V or else! it took me around 10 minutes to build.any link on how to characterize appliances power efficiency, power factor etc? by making a specific extension cord or tool so we can measure the Vac and Iac in oscilloscope? my Rigol will blow up if connected directly to Mains.i did search for Fluke Clamp Meter earlier, the price is like 6X at least compared to Uni-T. but i cannot find Fluke that can match exactly the UT202, ie for low home use 2A ACA spec, i found for industrial only, hundred/thousands of Amperage. But $30 UT202 is an expendable "toy".

author: jahonen
author_rank: Super Contributor
timestamp: July 10, 2011, 07:23:47 am
content: Quote from: Mechatrommer on July 10, 2011, 03:22:02 amFor scope, you can get a current and suitably CAT-rated differential voltage probe something like Fluke 80i-110s and Fluke DP120 (I have those). Not the cheapest ones probably but also not dodgy. Safety is not an issue with current probe if you have properly insulated conductor where you measure but for voltage, you must make a direct connection to the mains with the differential voltage probe. One problem with Rigol in this application is that IIRC it can't do a measurement on a math trace, so you can't get average of the instantaneous power, which would then give a true power.I also made a box for performing this kind of measurements. It has a loop for current probe and voltage taps bananas. But really you must know what you are doing when using something like this.Quote from: Kiriakos-GR on July 09, 2011, 06:56:19 pmThose Kill-A-Watt style meters available here in Finland were evaluated by HIIT, and you can read the reportHere. Some are quite good and some are bad. Problem with those is that models tend to change quite quickly.Regards,Janne

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: July 10, 2011, 10:02:52 am
content: Here is the solution that I have seen, and I will try to create the European version .

author: Mechatrommer
author_rank: Super Contributor
timestamp: July 10, 2011, 12:16:26 pm
content: Janne, can you provide the schematic for your box? i'm willing to learn.with PC/laptop, i think its possible to show instantaneous power.

author: armandas
author_rank: Frequent Contributor
timestamp: July 10, 2011, 12:50:17 pm
content: Quote from: Mechatrommer on July 10, 2011, 12:16:26 pmTry this one.

author: Mechatrommer
author_rank: Super Contributor
timestamp: July 10, 2011, 01:29:43 pm
content: Quote from: armandas on July 10, 2011, 12:50:17 pmhaha. i just realized it when googling on Fluke probe (which actually another clamp style) and how clamp meter work. its just my version of adaptor with nice box, banana and conector. so curious, i've teared down my ut202 to see if i can mod this to clamp probe, connected/tap 2 wires out of the white wires (leftmost in the picture), measure with oscilloscope. i thought i can measure some volt out of it, not a! i should study more on hall effect, found a pic on the net (schematic below). opened the UT202 manual (to find out if its used whether hall effect or current transformer), its all in chinese, no english. BAD!

author: jahonen
author_rank: Super Contributor
timestamp: July 10, 2011, 02:22:20 pm
content: Quote from: armandas on July 10, 2011, 12:50:17 pmYes, that is basically it. Just a loop with voltage taps.Regards,Janne

author: jahonen
author_rank: Super Contributor
timestamp: July 10, 2011, 02:41:23 pm
content: Quote from: Mechatrommer on July 10, 2011, 01:29:43 pmProbably current transformer since it doesn't measure DC.Regards,Janne

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: July 10, 2011, 03:24:03 pm
content: Quote from: Mechatrommer on July 10, 2011, 01:29:43 pmThe Hall effect clamps is only for rich people .. LOLThe cheapest ever, starts for 170$, fixed size open fork.Yes the AC clamps its common current transformers, that why they are cheap,and their output is in mA .I did a tear down of my AC/DC Chauvin Arnoux , and there is a tiny PCB strip, loaded with parts,but is surrounded by a flexible shield that covers all the PCB 360 degrees and its actually soldered in three key points.This shielding has few holes in some areas that there is parts like LED's or mini switch.And I found also three potentiometers, the ones with 40 turns , that are for calibration.1) Set zero volt.2) 0.2-40A range3) 0.4 - 400A rangeI did not take any pictures of it, even if I did take it all apart, for inspection and cleaning.It was exceptionally clean inside, and this translates to, that this second hand clamp probe,had never visited an industrial site.Got it just for 75EUR shipped, a true bargain for what it is and do.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: July 10, 2011, 03:38:50 pm
content: Quote from: jahonen on July 10, 2011, 02:22:20 pmBy measuring from a loop, you are in danger to get by some % higher readings than the real.But it does work as idea.

author: saturation
author_rank: Super Contributor
timestamp: July 10, 2011, 04:50:50 pm
content: For home use, a killawatt style device can't hurt, but as jahonen warns, beware of the type of model, as some are better than others. In the US, "KaW" has been around for almost 10 years, and many reputable folks have tested it, including state and local governments, but no formal reports I can find just unofficial endorsements to consider using one. Its not engineering quality, but it gives you a scale to adjust a device qualitatively at worst, quantitatively at best. In many US states, its even lent at libraries.http://alexandriava.gov/tes/gbrc/default.aspx?id=43956http://www.consumerreports.org/cro/magazine-archive/march-2009/appliances/energy-monitors/overview/energy-monitors-ov.htmNot many technical posts like the Finnish report, many anecodotal forum posts:http://www.silentpcreview.com/forums/viewtopic.php?p=485962#p485962For PF see:http://en.wikipedia.org/wiki/Power_factorQuote from: Mechatrommer on July 10, 2011, 03:22:02 am

author: jahonen
author_rank: Super Contributor
timestamp: July 10, 2011, 08:03:35 pm
content: This starts to be quite a bit off-topic but I have turned an old electric energy meter into a true power/energy meter by taking a pulse from front panel flashing led (I put an optoisolator LED in place of front panel led) into a microcontroller with a LCD. I then calculate power from time interval between flashes (10000 flashes = 1 kWh). It seems to be quite okay even for difficult non-linear loads. Although it is primarily a three-phase device, it works fine on one phase, when all phases are just connected together.Regards,Janne

author: torr032
author_rank: Regular Contributor
timestamp: November 24, 2011, 04:05:22 pm
content: which one is faster in autoranging ut61b or ut61c ?

author: IanB
author_rank: Super Contributor
timestamp: November 24, 2011, 07:19:01 pm
content: Quote from: alm on July 09, 2011, 02:36:35 pmResurrecting an old post, but clamp meters can be used when repairing electrical items like dishwashers or washing machines. You may need to determine whether power is making it to the heater, and whether the expected current is present. Once you are inside a device there will be separate conductors and the clamp meter can be placed around just one of them.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: November 25, 2011, 09:28:38 am
content: Quote from: torr032 on November 24, 2011, 04:05:22 pmWith how fast speed you will be happy with.If you look for speed daemons you looking at the wrong neighborhood.

author: torr032
author_rank: Regular Contributor
timestamp: November 27, 2011, 10:58:11 pm
content: maybe something like 61E. But I need a temperature measurment. And I don't really need 250mf capacitance. What about ut70B, by specs he fits my need, but what about speed and reliability, is he fast as a 61E ?