Good multimeter: which one?

Discussion in 'Test & Measurement Forum' started by FiNaR, Aug 21, 2018.

  1. FiNaR

    Thread Starter New Member

    Aug 4, 2018
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    Hi all,

    I'm an absolute beginner and I'm starting to play around with Arduino and home automation....

    As newbie, I wowou like to get a good multimeter that is not going to be useless in 1 year (when hopefully my knowledge and implementation will be more advanced), but at the same time I don't want to spend a fortune....

    Any good suggestion?

    Many thanks

    Ivan
     
  2. Hymie

    Member

    Mar 30, 2018
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  3. -live wire-

    Active Member

    Dec 22, 2017
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    I have a meter very similar to this one. I think mine is a slightly different model. I've had mine for almost a year and most of the time it's good enough. Sure, there have been times I wish I had a scope. But it is still incredibly useful, and a great deal.
     
  4. -live wire-

    Active Member

    Dec 22, 2017
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    Now, there are some things your multimeter can't measure. You may encounter these things later on. For example, it has a very hard time accurately measuring resistances within a few ohms, and certainly can't measure the resistance of the wires directly . But you can usually get around these limitations. For measuring small resistances, just send a few amps through the wire and measure the exact amps and volts dropped on the wire, With ohm's law, you can easily find the resistance, and determine many useful things about the wire. You also cannot directly measure inductance, which is very important to know in many applications. While you could buy an expensive LCR meter that can measure it, you can measure it by constructing a resonance circuit and doing a frequency sweep. Or, you can measure impedance by measuring current at different frequencies, and figure it out that way. You get my point.
     
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  5. panic mode

    Senior Member

    Oct 10, 2011
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    what i your budget?
     
  6. dl324

    AAC Fanatic!

    Mar 30, 2015
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    If you live in the US, Harbor Freight often gives away a multimeter with any purchase. It's probably worth $5-6 if you buy it outright. They're good enough for getting started and free is a decent price.
     
    FiNaR likes this.
  7. -live wire-

    Active Member

    Dec 22, 2017
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    I was able to get one for free. Sometimes you want to measure voltage and current at the same time, or something you can't do with just one meter. So it can be very useful for that. But the quality is low, and it is lacking in many features. And the "10 amp" connectors on mine melted at 4A. So unless your budget is really tight, then spending $15-$20 on a decent meter is definitely worth it.
     
  8. dl324

    AAC Fanatic!

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    I can't remember the last time I use a meter to take current measurements in a circuit. The meter resistance usually affects the circuit enough to give you erroneous readings. It's much more convenient to insert a low value resistance in the circuit and measure the voltage drop.
    What do you expect for free?? I keep one in the breakdown tool kit for each of my vehicles. I keep one in my tool bag for when I just need a quick voltage reading. I have spares for whatever...

    I have half a dozen or so better quality DVM's around my work bench.

    Starting out with a free DVM is fine. Once your skills outgrow it, you can get a better one. If you never reach that point, you didn't waste any money.
     
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  9. DickCappels

    Moderator

    Aug 21, 2008
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    I have checked several cheap digital multimeters, mostly by seeing how well the voltage measurements track those on my Fluke 75 meter. I have only come across one meter than I will not use at the bench and its not because of accuracy but because the input resistance is 1 meg ohm, which is too low for a lot of what I do.

    I have several UNI-T meters and they all perform well and have been holding up well for years.

    Consider that some day you will need to change the battery, and over the years that might be many times. The meters that are powered by a pair of AA cells (in my experience) go longer between battery replacements and AA cells are ubiquitous, 9V batteries often have to wait until I go out to buy one. The worst meter I had in this respect was a cute little pocket meter that used expensive and hard to find coin cells. Keep that in mind.

    Something that few people bother with is the ability to use a thermocouple.
    upload_2018-8-22_13-19-22.png
    The fact that a transistor or voltage regulator feels hot does not mean its over heating and with a thermocouple you can know with fair certainty whether something is wrong or not. The UNI-T UT33 is inexpensive and has this feature.
     
  10. dendad

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  11. BR-549

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  12. -live wire-

    Active Member

    Dec 22, 2017
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    It's still a good deal, given that it was free. But I really recommend getting a better one for $20, if it's going to be your only one. And how would a shunt resistor not also affect the circuit with its resistance?
     
  13. dl324

    AAC Fanatic!

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    The resistance of the two meters I've checked, by reading the manual, were both 1000 ohms on the 200uA scale. Any resistor put in a circuit for the purpose of measuring current would be of a value that didn't affect the circuit adversely; while giving an accurate current measurement.

    People who have used analog meters are more familiar with loading affects caused by meters that can affect the accuracy of measurements. The first analog meter I owned had a load resistance of 50k ohms per volt.
     
  14. rsjsouza

    Member

    Apr 21, 2014
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    Several good options above. For your scenario a very useful multimeter is also the Uni-T UT136C (sold by Amazon as Sinometer UT-136C), which is very compact, sturdy and is not plagued by the common issues I have seen with cheaper multimeters (I have one for two years now). Also, this meter is well furnished with features and, as you progress in your electronics development, it will still be quite useful as a secondary meter.

    A small list of details that make a difference during the decision process is shown below. This is not comprehensive by any means.
    - Quick autoranging - several of the cheap multimeters can be quite slow to find the value across the ranges.
    - Good diode tester that can lit higher voltage LEDs (above 3V).
    - Decent frequency/duty cycle meter - most cheap multimeters do not measure frequency if it has a DC offset, which is something important for digital systems.
    - Decent accuracy when bought new and after one year of use - most of the multimeters are good with the accuracy, but the bad ones tend to drift a lot over time.
    - Unfused 10A or 20A input. That may not be too problematic for low energy circuits, but a distraction and you can cause quite a damage to your projects.
    - Decent manufacturing - it is not uncommon to see low quality plastics, scratches or the occasional dust or dirt inside a brand new cheap meter. More serious problems involve loose solder blobs or parts rattling inside the meter (could cause short circuits), poor solder connections on fuses or on the input connectors (which can break with use) and rust or dirty contacts that cause fluctuations on measurements.

    Other minor aspects that may or may not make a difference for you are:
    - True RMS: this is contentious. In my opinion, the work on small microcontroller systems this option is not entirely relevant, but others may differ.
    - Backlight: this is important for some people.
    - Power: depending on where you live, 9V batteries are quite expensive and AA or AAA batteries are a better option. However, AA/AAA batteries leak a lot more easily.
    - Temperature: several of them have temperature sensing, which is quite interesting to avoid burning your fingers on the occasional overloaded part. For others, this is useless.
    - Non-contact detection: several meters allow detecting energized outlets and wiring inside walls, but if where you live uses 100V/115V/127V and the multimeter only detects 220V or more, this becomes a useless feature. Always read the user's manual thoroughly.
    - Square wave output. Some people like it, but to me it is too limited for any practical use. That and the fear of blowing out its ouput due to overloading it with a circuit that misbehave.
    - Transistor tester. An almost useless feature (only good for quick checks) that detracts from the safety of the meter.
     
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  15. FiNaR

    Thread Starter New Member

    Aug 4, 2018
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    I would say 30$....
     
  16. FiNaR

    Thread Starter New Member

    Aug 4, 2018
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    Living in Europe ... Nothing free here :p
     
  17. dl324

    AAC Fanatic!

    Mar 30, 2015
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    Well, I wouldn't recommend relocating to get a free meter. $30 will buy a number of decent meters. The one I use most frequently is now down to about that price.
     
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  18. MrChips

    Moderator

    Oct 2, 2009
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    My first meter as a teenager was an AVO Multiminor MK4 which I still have and use when nothing else is available. Buy a quality instrument and it can last a lifetime.

    [​IMG]
     
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  19. FiNaR

    Thread Starter New Member

    Aug 4, 2018
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    Yeah that's about my budget... I could actually push it to 30 :p ...

    I am surprised that you all suggest "a Chinese one".... Considering the cost of a FLUKE.... Probably electronic works regardless the brand ....
     
  20. MrChips

    Moderator

    Oct 2, 2009
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