Which Multimeter Should I Choose for My Agricultural Engineering Degree?

[MJay82]

Hello all. I'd like to purchase a multimeter very soon. I'm pursuing an Agricultural Engineering degree with a focus on electrical/electronics. I also have interest in designing amplifiers and guitar effects pedal. Although I'd prefer to find a nice model for around $100, I always prefer a great buy, so if I have to pay extra now for something that will be worth it down the road, I will entertain the idea of more expensive units.

Does anyone have a recommendation?

 

[Topher925]

You may find this of interest: http://www.eevblog.com/2010/07/11/e...probe-bk-precision-ideal-uei-uni-t-part-1of2/

 

[berkeman]

You may find this of interest: http://www.eevblog.com/2010/07/11/e...probe-bk-precision-ideal-uei-uni-t-part-1of2/

Cool link, Topher. Could you add it to the "Useful EE Links and Search Engines"?

Thanks.

 

[MJay82]

Thank you! I'll watch that as soon as my room cleans itself. Hopefully magically. :)

 

[Studiot]

$100

Students must be made of money these days. Can't see why you need to spend anything like that for starters. None of the meters in the attached pic approach this value.

Set of meters and testers standard in my field case.

The ruler at bottom is 300cm or 1 foot long

From left to right along top

Mains power tester displays power, voltage, current, frequency & power factor.

Multimeter

The multimeter does, volts, amps, resistance, transistors, diodes, temeprature, humidity, light flux, sound intensity, semiconductor tests, continuity.

Battery tester applies dedicated loads, has spring loaded coin cell fitting.

Computer psu tester

Second row

Battery eliminator tester and polarity indicator accepts various jacks
Mains socket wiring checker checks line neutral & Earth for correct operation

Third row

Telephone socket and line function tester.

 

[berkeman]

$100

Students must be made of money these days. Can't see why you need to spend anything like that for starters. None of the meters in the attached pic approach this value.

Set of meters and testers standard in my field case.

The ruler at bottom is 300cm or 1 foot long

From left to right along top

Mains power tester displays power, voltage, current, frequency & power factor.

Multimeter

Nice set of meters!

Actually the DT-21 (2nd from the left) does retail for $100, but can be found down to $60:

http://www.metershack.com/electrica...mometer-light-humidity-sound-multi-meter.html

.

 

[turbo]

My work-horse is an Extech that I bought at Radio Shack. Less than $60 at the time. It does everything I need with acceptable accuracy. My electronic interests generally involve vacuum-tube circuits where Fluke accuracy isn't required.

I recently found a need for a clamp-meter and ended up paying $80 for such a meter with fewer overall capabilities than the Extech.

 

[Topher925]

$100

Students must be made of money these days. Can't see why you need to spend anything like that for starters. None of the meters in the attached pic approach this value.

I used to be the same way until my $30 meter exploded checking a LiPo. If you're a student that does any actual technical work, I would invest a lot more than $100 on a meter. Its something you will use for many years and worth the investment. I bought my meter for $200 and it was worth every penny. Having a calibrated meter that you know you can rely on is an item that I don't think you should skimp on. Features like high current diode test, dual thermocouple readers, data-logging, and all the nice safety features to make sure you don't kill yourself or the meter are very nice too.

 

[berkeman]

I used to be the same way until my $30 meter exploded checking a LiPo.

Okay, I have to ask. I Googled LiPo, and all I get are advertisements for Liposuction :tongue2:

What's a LiPo, and why did it make your meter explode?

 

[turbo]

Okay, I have to ask. I Googled LiPo, and all I get are advertisements for Liposuction :tongue2:

What's a LiPo, and why did it make your meter explode?

And who would purchase or use such meters? I have owned a TON of meters since the 1960s. None of them posed a risk of injury or death.

 

[vk6kro]

Okay, I have to ask. I Googled LiPo, and all I get are advertisements for Liposuction :tongue2:

What's a LiPo, and why did it make your meter explode?

Probably Lithium ion Polymer battery. I'd guess it blew up because it tried to measure voltage on a current range.

I have a multimeter that measures inductance and capacitance and has lots of voltage and current ranges, but mostly, I use an $8 meter that let's me keep the leads in the same sockets all the time.
It spends most of its time on the 2 volt and 20 volt ranges with excursions to the diode and transistor test function. It has 1% accuracy and if I do something stupid with it, it is no big deal.

I wouldn't be suggesting a beginner go get a Swiss Army knife multimeter with a ton of functions he'll never use.

 

[Topher925]

Okay, I have to ask. I Googled LiPo, and all I get are advertisements for Liposuction :tongue2:

What's a LiPo, and why did it make your meter explode?

Ha. LiPo is short for Lithium Polymer Battery. It made my meter explode because I tried to measure the voltage of the battery but had the meter set to resistance measurement.

I used a meter such as that because its all I could afford at the time and didn't have nearly as much experience with electrical equipment as I do now.

BTW, my $200 meter doesn't care if I put a high voltage across it on the resistance setting, not even 220VAC. Its almost completely Topher proof.

 

[MJay82]

$100

Students must be made of money these days. Can't see why you need to spend anything like that for starters. None of the meters in the attached pic approach this value.

Some of my fellow classmates (younger than me) spend more in a weekend on drinks. Many others have hundreds, if not thousands, of dollars worth of clothes. Others find value in expensive television sets and the new Call of Duty. Me - I'm a simple guy. I work at the school and take classes, eat at the house and sleep. So yes, I've got a little money set aside for items which I perceive as necessary to forward my academic (and just general engineering) endeavors.

Besides, "these days" $100 is not a lot of money.

Topher - as I said, I don't want to spend $100 now just to have to turn around in a few years to spend twice as much. I'd rather spend the $200 (or more really, if truly needed) now. So what would your recommendation be in the $200 neighborhood? I don't have much to go on - my physics teacher just told me to "inductance and capacitance". At the same time, I don't want to pay for a name, so if there's something out there that's Fluke quality without the name, it makes no difference to me. I guess what I'm trying to say is, I'm looking to make an investment here that will pay off in the long run.

 

[AlephZero]

Some practical advice: don't just but one "high quality" meter. Buy a second cheap one as well, so you won't mind too much if you drop it 20 ft onto a concrete floor, or get it covered in various biological materials you will find in an agricultural environment, or whatever.

There are plenty of times when even a meter with a 10% error is good enough to tell you what you need to know, and there's no sense in risking damage to a precision measuring instrument when you don't need to use one.

Being able to measure two things at once can sometimes save you a lot of time as well.

And if you accidentally use an expensive meter on the wrong range setting, it will blow up just as effectively as a cheap one. I know that from personal experience...

 

[MATLABdude]

I'll make some general recommendations, based on my (limited) experience. Names to trust for (portable) DMMs

• Fluke -- almost certainly outside your price range you pay for the calibration, rock steady reliability, and name / quality
• Agilent -- see Fluke, except probably more expensive
• Amprobe / Meterman -- the budget range of Fluke (at least, it was the last time I checked)
• Extech -- probably just a hair below Amprobe / Meterman, but still excellent quality

As for features to look for:

• Volts (at least ~600 AC/DC), Ohms (at least 10 MOhm), Amps (at least 10 A, AC/DC), continuity checking (the annoying and extremely useful beeping when a low-resistance path exists between the two leads) and diode check are non-negotiable.
• Capacitance, inductance, frequency / PWM, are really nice to have--transistor check is pretty hit or miss, in my opinion
• Ruggedness -- I don't know about you, but I've dropped my meter more than a few times: the rubberized case (or applique rubber pads) have saved it in all these instances
• Autoranging -- comes in extremely handy, since you don't have to worry about blowing the meter / fuses at lower ranges, and since you don't have to fiddle with the meter when you have large dynamic changes
• Data logging / PC interface (preferably USB, unless you still have a computer with a serial port on it) -- comes in really handy when you need to take measurements over a long period of time

 

[Topher925]

So what would your recommendation be in the $200 neighborhood? I don't have much to go on - my physics teacher just told me to "inductance and capacitance"

It really depends on what you're going to be using it for. Are you using it for more power based applications, like motors or mains power, or are you going to be using for low voltage/power electronics work, or both? You're probably not going to find a good meter that measures inductance unless you're paying some big bucks. You'd be better off just getting a separate LCR meter that will do that. It will be more accurate and give you more info (like ESR) than any DMM can.

I'm a fan of Agilent meters as you get a lot for the money. I've got a u1242b that I really like. They perform just as good as Flukes, have more features, but aren't quite as durable. They also come completely calibrated with Cal Cert. Gossen Metrawatt makes the best of the best but are also extremely expensive. Extech makes some water and dust proof meters that are OK for they money.

If I had to recommend something for $200 it would obviously be the u1242b as that's the one I decided to get. Its a 10k count meter, includes a cal certificate, plus built in temp sensor, and measures things FAST. Like snaps to a resistance or voltage and doesn't budge. It retails for about $220 but you can often find it for under $200 with a coupon. If you're doing more power or industrial stuff the new u1271a is suppose to be a really great meter but has a steep price tag of $340. If you can post more about what applications you will be using the meter for I can provide better suggestions.

 

[Topher925]

Like AlephZero said, its good have a cheap meter lying around as well. If you ever order anything from www.circuitspecialists.com for over $50, you can get a free DMM. I've got one or two in the lab at school and they're great for leaving in oven's or cold chambers.

And if you accidentally use an expensive meter on the wrong range setting, it will blow up just as effectively as a cheap one. I know that from personal experience...

I have NEVER blown up a good meter before, and I've tried pretty hard. I blew a fuse in a Fluke 87IV before measuring current from a 60VDC source before but the thing certainly didn't explode. Usually, as long as you stay below 300V, you will probably never do more damage than blowing a fuse.

 

[turbo]

If you spend more than 50-60 bucks or so on an auto-ranging meter, it's not going to blow up. It might take a fraction of a second longer or for that meter to stabilize and display a reading, but it's probably still a good meter. I am very happy with my cheap Extech meter and I think that anybody that screws around with electronics will agree. Nice rugged meter with ribbed hugging rubber armor... Does getting another 1/10th of a volt, etc, justify the cost of a top-drawer meter?

 

[Carl Pugh]

Buy two or maybe four of these.
http://www.harborfreight.com/catalogsearch/result?category=&q=multimeter
7 Function Digital Multimeter
Only:$9.99
Sale:$4.99
They are great little meters.
The only thing anyone could complain about is that they only have 200 and 750 VAC ranges.
Have checked their resistance reading with many 1% resistors and they always read withing 1% of resistor markings.
Have also check a few of the voltage ranges and they were always very accurate.

 

[turbo]

Buy two or maybe four of these.
http://www.harborfreight.com/catalogsearch/result?category=&q=multimeter
7 Function Digital Multimeter
Only:$9.99
Sale:$4.99
They are great little meters.
The only thing anyone could complain about is that they only have 200 and 750 VAC ranges.
Have checked their resistance reading with many 1% resistors and they always read withing 1% of resistor markings.
Have also check a few of the voltage ranges and they were always very accurate.

Nice! I'm already covered, but I'd buy a few of these if I were not.

 

[Studiot]

I only hope you really want to do electrics/electronics rather than own a status symbol.

Yes you can indeed blow up even expensive meters, as I know from bitter experience with the european equivalent of Fluke - a Dilog.

Yes I also have an Avo, a Fluke amongst other things. The point I was trying to show was that you will require more than one meter if you are serious.
Aleph Zero and Carl Pugh have made this same point. Two meters enable you to monitor/compare different points in a circuit, monitor voltage and current simultaneously and so on.
Meters with auxiliary functions such as LCR, semiconductor tests etc are often better consigned to a separate instrument. It is of no use to want to know the value of a capacitor when your only multimeter is already clipped into circuit monitoring the power rail.

The other problem with expensive meters is that the initial cost is not the only, or even largest, cost.
If you use them for work purposes the cost of annual certified calibration can soon exceed the intial cost.
This is not trivial in these days of certification madness. The latest NASA satellite launch was certified to the hilt but still didn't work.

I showed a range of dedicated meters and testers I carry round for computer work. You have stated that you are studying agricultural engineering and have a (side) interest in audio electronics.

For audio work your budget would stretch to a scopemeter, rather than a multimeter. Also include (add) a cheap signal source. Perhaps a cable tester fixture jig.
Such devices are also more use in digital electronics where a traditional multimeter has very limited application.

The most successful instrument ever from the now defunct, but formerly world famous, Marconi Instruments was the silage tester - yeah!
This was a cheap moisture content meter.
In agricultural engineering I expect you may well be dealing with machinery. A very useful type of multimeter are those that are made specifically for the auto industry. In addition to the usual VIR functions they contain (depending upon their specification) engine specific functions such an rpm meter, timing function and so on.

Finally while you are still at college you will probably have access to a lab where you can calibrate even the cheapest meter to any desired accuracy for your own purposes (although you will not get a certificate).

go well

 

[MJay82]

Thanks for all the help, everyone. I'm still unfamiliar with some of these acronyms, or even exactly what it is that I need. I've got a Borders coupon for 40% off good through the weekend. I'm going to go peruse their EE/electronics section today. I'm just now taking the second part of the introductory physics course - emag and optics.

Studiot - you pegged the interests. I think though that the program I'll be entering (I'm transferring in the summer) focuses specifically on sensors' roles in an agricultural setting. I'm not sure how much heavy equipment I'll be dealing with, but I hope to be prepared for all circumstances.

My primary concerns at this point though are getting the tools necessary to tinker around with the idea of building an amplifier, which is what I was encouraged to do by my physics teacher for my project this semester.

Carl - we've got a Harbor Freight store in town, I might just go buy one of those cheapies there so I can play over spring break! Thanks for the heads-up!

 

[Studiot]

http://vimeo.com/10492394


Above is a review of a scopemeter (not a Fluke) but coupled with the Tenma portable signal generator as in my pic they make a super audio test and development set that would be within your budget.

On the link, Alistair George also shows some other useful videos for budding electronics techs.

 

[turbo]

I have a few little cheapo meters for tool-box, vehicle, etc, but these are the two that get me through 'most anything. The clamp-on is handy, because it's really nice to be able measure amps on the fly without breaking a circuit and shunting current. Having a second auto-ranging multimeter on hand let's me measure two values at once. Neither of these meters are expensive - I got them both at Radio Shack, and they both came with cases, leads, thermocouples, etc. Buying an equivalent set of meters would run less than $150, and as long as you don't need calibration/certification, they are fine.