Cheap around $50 Multimeter - Page 1
Forum section: electronics / beginners

author: SuperMiguel
author_rank: Regular Contributor
timestamp: April 30, 2010, 04:33:07 am
content: Im an EE student and my cheap $5 is giving me wrong values... As a college student i dont have much money.. I was going to save up for a fluke but i guess is not worth it now since im doing basic stuff..So for around $50 whats a good multimeter???So im kinda betweenhttp://www.sparkfun.com/commerce/product_info.php?products_id=8657andhttp://www.amazon.com/Extech-EX330-Autoranging-Multimeter-Thermometer/dp/B000EX0AE4/ref=pd_cp_hi_2Whats you guys opinion?

author: EEVblog
author_rank: Unknown
timestamp: April 30, 2010, 09:07:19 am
content: Hold off.I'm reviewing all these meters soon:https://www.eevblog.com/forum/index.php?topic=323.msg4148#msg4148Dave.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: April 30, 2010, 12:03:16 pm
content: Hello@SuperMiguel, your choice looks to be aUnit-Tone, that is an well known and respected brand in Europe.If you do know, what you are looking for, just get it.If not, its advisable to see the upcoming review, some times there is small details, that makes the deference.

author: EEVblog
author_rank: Unknown
timestamp: April 30, 2010, 12:43:31 pm
content: I hate the Uni-T bench meters we have at work!Dave.

author: SuperMiguel
author_rank: Regular Contributor
timestamp: April 30, 2010, 02:12:01 pm
content: i also tought about getting the fluke 115 but dave mentioned on his 117 video that it was an electrician multimeter since it didnt have mA nor microA and that this wont be good for electronics but not sure if this applies to the 115 If you look at the specs in the link below the AC and DC 6 amp max range will resolve down to .001 amps which equals 1 ma.http://support.fluke.com/find-sales/Download/Asset/2634043_6116_ENG_B_W.PDF

author: saturation
author_rank: Super Contributor
timestamp: April 30, 2010, 02:59:11 pm
content: Any quick quip as to why Dave?Quote from: EEVblog on April 30, 2010, 12:43:31 pm

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: April 30, 2010, 08:21:59 pm
content: Quote from: EEVblog on April 30, 2010, 12:43:31 pmI hate everything we have at work too , because its tools = work = not fun ...Today I just read the full users manual of the 87-5 .( I had printed it )There is lots of good info in it , and about 80 times in 40 pages, the wordsHazard - warning - Do not .

author: SuperMiguel
author_rank: Regular Contributor
timestamp: April 30, 2010, 09:20:56 pm
content: i have about $300 to spare right now.. I can get the Fluke 179 or i can buy a cheap one ($60) and save money for an O'scope... Ummm but i dont want to buy a multimeter now and then next semeter i have would have to change it because its crap ummm

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: April 30, 2010, 10:27:20 pm
content: No one are able to guide your buying decision , by having in mind your own future needs !!!Even the most expensive ones , are specialized in some areas only ..So its in your fate , to own more than one .If you find the ultra perfect " I do all " DMM in the range of 300$ please inform us too.

author: EEVblog
author_rank: Unknown
timestamp: April 30, 2010, 11:03:37 pm
content: Quote from: SuperMiguel on April 30, 2010, 02:12:01 pmYes, but that's 1mA resolution (+3 digits), which is next to useless for electronics. i.e is your PIC really drawing 5mA which it says, or is it 2mA-8mA?, you just can't be sure. You need better resolution than 1mA for electronics, you need uA resolution as I mentioned.Dave.

author: SuperMiguel
author_rank: Regular Contributor
timestamp: April 30, 2010, 11:29:01 pm
content: how about the ex430?True RMSBasic Accuracy (VDC) ±0.3%AC Voltage 0.1mV to 750VDC Voltage 0.1mV to 1000VAC Current 0.1?A to 20ADC Current 0.1?A to 20AResistance 0.1? to 40M?Capacitance 0.01nF to 100?FFrequency 0.001Hz to 10MHzTemperature (Type K) -4 to 1382°F (-20 to 750°C)Duty Cycle 0.1% to 99.9%Continuity / Diode Yeshttp://flirextechcompletesolutions.com/instruments/resources/datasheets/400series.pdf

author: saturation
author_rank: Super Contributor
timestamp: May 01, 2010, 01:53:41 am
content: If you can, wait for Dave's review. For $300 on Amazon, you can get an 87V new. I'm not sure where you live, taxes, or cost to ship.A problem with other meters is do they really live up to the spec sheet they publish, and I think Extech is a good bet. Its $100 at Amazon. But as you read its specs its rated CAT III for protection, whereas the 87V Fluke is rated CAT IV. Also, I can say for certain you can drop the FLuke at 3' without a problem, and my 85 has held its calibration and accuracy for over 20 years. I paid ~$300 for that Fluke then, but its so durable, I still use it now.If you are cash strapped, get something in the $50 range than will give you good reliable 0.5% V and A, AC and DC. Cost won't be such a big issue when you graduate, are employed and making money and as a pro you'll get what saves you time by being accurate and durable. As Dave has said, in real life you'll need more than one meter, so you can make simultaneous measurements and monitor various portions of a circuit, so you can still use your old meters if they are still working. I own 4 but the Fluke is the one I trust.Quote from: SuperMiguel on April 30, 2010, 09:20:56 pm

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 01, 2010, 02:14:21 am
content: School - students - stealing - not safe environment.If I had ask my father when I was in your age, he would said get the cheapest one, and later on, you will get a better one.Industrial specs and high resolution , comes slowly in our life's.I can not imagine any student to like, to carry one 600 grams brick, here and there..

author: SuperMiguel
author_rank: Regular Contributor
timestamp: May 01, 2010, 05:30:33 am
content: do i need true RMS for electronics?

author: DJPhil
author_rank: Frequent Contributor
timestamp: May 01, 2010, 07:37:09 am
content: Quote from: SuperMiguel on May 01, 2010, 05:30:33 amI would say yes, very much so, or at very least you need to know the limitations of your meter.Those that are not true RMS for AC measurements are almost always assuming a perfect sine wave, especially if they're inexpensive. In electronics you will deal with all sorts of wave shapes, and a true RMS meter will give you vastly more accurate readings for wave shapes that are significantly different than sine waves. This crops up an awful lot in electronics, but not very often for the average homeowner who's testing batteries or working on their car.Don't get me wrong, you can certainly survive without it. You just have to remember what your meter is doing when it's measuring AC voltage or AC current. If you're working with a square wave or triangle wave you may be able to compensate with math, but for anything not mathematically simple you won't get a meaningful measurement.In my opinion it's a fundamental criterion for a multimeter used in electronics, and I wouldn't buy a meter without it. My advice would be that if you're going to be working with electronics for a while and you don't yet have a decent meter, make true RMS mandatory.

author: StephenOng
author_rank: Newbie
timestamp: May 01, 2010, 08:58:31 am
content: Quote from: SuperMiguel on May 01, 2010, 05:30:33 amI find there are very few cases where a RMS meter is more useful than an averaging meter.When the time varying signal is non sinusoidal both kind of meters are usually useless. You will want to see the waveshape with an oscilloscope.

author: Unknown
author_rank: Unknown
timestamp: May 01, 2010, 11:39:02 am
content: Quote from: StephenOng on May 01, 2010, 08:58:31 amSure, a scope is a useful tool too, but that's kind of off-topic for this discussion. I would argue that if you don't have a scope, you need an RMS meter even more. An average-responding meter will give wrong results for non-sinusoidal signals, how do you know if your signal is sinusoidal without a scope? You'll never know if the meter is reading correctly. An RMS meter will always give the correct result (provided the signal is within its bandwidth and crest factor). You may not know if it's a square wave or a sinus, but at least you know the real voltage (which is what a multimeter is for), not some fictional 'if this was a sinus' voltage.

author: StephenOng
author_rank: Newbie
timestamp: May 01, 2010, 01:31:30 pm
content: Quote from: alm on May 01, 2010, 11:39:02 amFor electronics use, I'd put RMS meter in the nice to have category. As for a scope, I don't think I can live without oneQuote from: alm on May 01, 2010, 11:39:02 amTime varying signals don't have "real" voltage. They have voltage distribution which enable statistical values like average, peak and RMS value to be calculated. RMS is only relevant for power calculation. I think it is rare in electronics to have power issues due to AC non-sinusoidal signal.However, given that true RMS is usually found on better multimeters, it is good to get a true RMS meter.

author: Unknown
author_rank: Unknown
timestamp: May 01, 2010, 02:24:36 pm
content: Quote from: StephenOng on May 01, 2010, 01:31:30 pmI'd probably agree, especially since digital scopes can measure voltage with a reasonable accuracy. Although the extra cost for an RMS meter is usually a lot less than a scope (both new DMM vs. new scope and used DMM vs. used scope).Quote from: alm on May 01, 2010, 11:39:02 amThe voltage of an AC signal is quite real, but it isn't a single value but indeed a function of time. However, average-responding meters don't actually report the average rectified voltage, but report the average rectified voltage multiplied by 1.1 (so it will yield the RMS voltage for sinusoidal signals). So they try to report the RMS value, but do so in a way that only works for sine waves. So for a 5Vp-p square wave, it will report 5.5V. This is neither the RMS, average or peak-to-peak voltage, and is just a fictional number. This is why I called results from a true RMS meter real, and from an average-responding fiction as soon as the signal is not sinusoidal. I agree that the peak-to peak value is sometimes more useful, but an average responding meter won't give you that either, it will just be a worse approximation of the RMS voltage.Whether it's important depends on the applications. Anything involving switching power supplies, noise or distorted signals (eg. a power rail modulated by the loading of digital circuits) would benefit from true RMS.Quote from: alm on May 01, 2010, 11:39:02 amActually the previous Fluke 25/27 (eg. without the II), and the Fluke 70 series (even the current I think) don't feature true RMS, so it's a premium feature, even for Fluke. Given the choice between something like a Fluke 77 without true RMS and a cheap, feature-packed meter with true RMS, I'd probably prefer the Fluke, although I'd probably buy neither. It's just to easy to pick up cheap used brand-name meters (especially bench meters) for under $100 to bother with the cheap stuff in my opinion, at least for me.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 01, 2010, 03:05:26 pm
content: This well made video it will help allot in this conversation.Still , I strongly believe, that True RMS , has mostly to do with people who repairs inverters.The AC in our homes , and industrial locations, are perfectly perfect.If some one, does not do installations or servicing, large AC motors or inverters , does not need True RMS tools at all.

author: SuperMiguel
author_rank: Regular Contributor
timestamp: May 01, 2010, 03:34:47 pm
content: The reason i ask is because everyone tells me not to buy an expensive multimeter now, to wait until i finish school and then get one based on my job requirements, also people tell me to buy a cheap multimeter and save for an Oscope.. So i guess ill go cheap but not that cheap/ and im trying to decide between the extech ex430 ($86) and the ex330 ($56) seems like the biggest difference is that the ex430 has true RMS... By watchikng that video posted by Kiri it seems like i need T-RMS so for $86 is the extech ex430 my best bet???

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 01, 2010, 06:36:56 pm
content: Quote from: SuperMiguel on May 01, 2010, 03:34:47 pmWell there is no such description when we look for tools.Not even expect , that some one else will examine all the target group of meters that you are interested about, so to save you from the trouble of finding "The right one " by your self.Even Dave is limited to the most marketed brands in Australia.And I, from Greece, I am also limited , to the goodies available in my market.Still our Dave, had all ready point out useful tips about selecting a DMM ,like having"auto range"in the voltage scale.Fast refresh time , and decent probes.

author: DJPhil
author_rank: Frequent Contributor
timestamp: May 01, 2010, 06:54:01 pm
content: Quote from: SuperMiguel on May 01, 2010, 03:34:47 pmI understand. To help with context a bit, a good deal of my zeal comes from not having regular access to a scope myself, as I'm still saving for one too.The posts above gave a great account of both sides of the issue, and did an excellent job of moderating my heavy bias. It really does depend on what you expect to be doing as to how valuable true RMS would be. Either way, at least you know what you're dealing with now.Quote from: SuperMiguel on May 01, 2010, 03:34:47 pmYou're coming up to the low end of Dave's big meter shootout. If you can wait, it's sure to be a valuable resource in your decision making.There are a few differences between those two meters that I would consider important, but let's say for the sake of argument that they're equivalent in value to you aside from true RMS. The question would be whether the extra $30 for true RMS is worth it to you, given your situation. It would be worth it to me if it was going to be my best or only way of measuring AC voltage and AC current for a while and I wasn't going to have a scope for at least few months. Consider also that someday this meter will be your 'second' meter.Hope that helps

author: EEVblog
author_rank: Unknown
timestamp: May 06, 2010, 11:04:47 pm
content: I'll be reviewing the EX330 and the EX505True RMS can be one of those "I wish I had it" features when you actually need it, so I think personally it would be money well spent. But that being said I can understand the attraction to the sub $50 meters.If I had to chose between having only one $100 meter with TrueRMS, or two $50 meters without True RMS, I'd go for the two $50 meters.Dave.

author: saturation
author_rank: Super Contributor
timestamp: May 10, 2010, 06:32:51 pm
content: Quote from: SuperMiguel on May 01, 2010, 05:30:33 amYes. The only reason to use true RMS meters is in electrical work, where most DMM type work is on dirty AC line voltage, and more importantly at 50-60 Hz. Beyond those frequencies accuracy starts to vary. Most DMM specs now report AC only up to 500 Hz.In AC work, the presence of harmonics will distort the pure sine wave, and thus, also affect the readings; likewise non-sine waves also alter the readings such as square and triangular waveforms. The RMS meters are more immune to these effects.Electronics work is very common with varying frequencies, and again RMS meters read better herein too.Note, for some Fluke meters, the difference is not that marked when it comes to sine waves, so a Fluke non-RMS meter does well in measuring AC sine waves up to its rated frequency. Since electronics work may likely be in a 'cleaner' environment, a true RMS DMM is not as necessary. Averaging ACV for pure sine waves give much better accuracy across all tested frequencies, at least by Fluke's standards, compared to the higher frequency range using true RMS; at worse its reporting 2% +20digits!Enclosed are the specs of the 83, 85, and 87 in ACV and AC A comparing averaging AC versus true RMS.Compare it against the spec sheet of the Extech 430, and note its true RMS is far more inaccurate that the averaging reading Fluke 83.