Author Topic: Why get a multimeter  (Read 6344 times)

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Offline Ferroto

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Why get a multimeter
« on: February 09, 2010, 01:58:56 am »
I was wondering what would be better if i could only get 1, a multimeter or an oscilloscope. Then I got thinking why do we need both instruments. Can't an oscilloscope measure just as high voltages as a multimeter with a greater degree of accuracy. A multimeter gives voltage in realtime, an oscilloscope gives voltage OVER time. A decent oscilloscope will cost almost 400$ and a decent multimeter about the same. There are hand held oscilloscopes available as well as handheld multimeters.
 

Offline Murphy

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Re: Why get a multimeter
« Reply #1 on: February 09, 2010, 02:19:17 am »
I'm not enough of an expert to comment on accuracy for voltage but remember a multimeter doesn't JUST measure voltage. Multimeters also measure current, resistance, capacitance, diode voltage drop, and have that nice continuity test beeper. Maybe other functions if you have a fancier meter. Also, oscilloscopes aren't very portable and the ones that are and are still good are in the many thousands of dollars (and still large).

Both are necessary and at least a cheap multimeter is an essential to work with electronics, even if you had the most expensive oscilloscope in the world.

Why would you only get one???
 

GeekGirl

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Re: Why get a multimeter
« Reply #2 on: February 09, 2010, 03:10:57 am »
I was wondering what would be better if i could only get 1, a multimeter or an oscilloscope. Then I got thinking why do we need both instruments. Can't an oscilloscope measure just as high voltages as a multimeter with a greater degree of accuracy. A multimeter gives voltage in realtime, an oscilloscope gives voltage OVER time. A decent oscilloscope will cost almost 400$ and a decent multimeter about the same. There are hand held oscilloscopes available as well as handheld multimeters.

A Good Multimeter will have a high end ADC with a high accuracy and 12+ BIT ADC. most of the DSO,s on the market around the same price EG Rigol are only 8 bit.

A multimeter is doubly insulated, NOTHING is referenced to Mains earth so I can do voltage mesurements anywhere, with the probes anyway around ;) A scope has one side of the probe (ground) at mains ground, which will if used wrong blow the circuit and posibly damage the scope.

a Decent Multimeter may be CatIII 1000V Cat IV 600V (I doubt you will find a scope as good for under us$10K)

It is all about using the right tool for the right job.
 

Offline EEVblog

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Re: Why get a multimeter
« Reply #3 on: February 09, 2010, 03:47:38 am »
An oscilloscope won't easily measure resistance, current, diode voltage drop, capacitance, or continuity beep. Not to mention as safely, accurately, or quickly (autoranging) as a multimeter.
It's called a "multi" "meter" for a reason!

It's no contest at all.

BTW, even the most expensive oscilloscopes are only 1% or worse in vertical accuracy, and usually only 8 bits at that. Not even close to the accuracy or resolution of even a $20 no-name multimeter.

GeekGirl nailed it on the head by saying, "It is all about using the right tool for the right job. "

Dave.
 

Offline Neilm

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Re: Why get a multimeter
« Reply #4 on: February 10, 2010, 06:45:18 pm »
It might be of interest to know that there are adapters that can be used (quite safely) to uprate an ordinary oscilloscope to make CAT IV measurements. I use one to do measure voltage transients.

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Offline Zero999

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Re: Why get a multimeter
« Reply #5 on: February 10, 2010, 10:28:55 pm »
I don't see why you shouldn't be able to afford a meter, if you can afford a 'scope.

Meters are cheap, 'scopes are expensive.
 

Offline rossmoffett

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Re: Why get a multimeter
« Reply #6 on: February 11, 2010, 12:59:38 am »
Buy both.  Get an analog used scope and the highest quality multimeter you can afford after that.  The Rigol scope that Dave reviewed is indeed an awesome buy (I just got mine in the mail today) but I have some analog scopes that will be just as good for most of my purposes.

Remember that you should buy your scope with the specs you will need, not just the ones you want.  If you're working on audio, a 1 MHz scope is sufficient.  This is so low that you probably won't find one.. more like 10-20 MHz.  Once you're in the 10-20 MHz range you've covered all motor control, power supplies, most micro-controllers and all audio devices out there.  It depends on what you want to work on/build.  If you keep this in mind, you'll find that oscilloscopes can be a bargain.

If you're planning on doing analog circuit design, you might find yourself naked without a function generator also.  Then you're going to want a power supply, and so on..  you can do a lot of stuff with just a multimeter though.
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Offline flolic

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Re: Why get a multimeter
« Reply #7 on: February 11, 2010, 08:15:20 am »
  Once you're in the 10-20 MHz range you've covered all motor control, power supplies, ...

 IMHO, 10MHz (analog) scope is not enough for troubleshooting most of switching power supplies. Those scopes usually have low CRT acceleration voltage which results in very dim trace at fast timebase. Also bandwidth is not enough to properly see eventual ringing and overshoot. Yes, you can see basic waveform but not so easily interesting parts of a signal  ;D
That's the reason I sell my 20MHz analog and bought 100MHz digital.
 

Offline qno

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Re: Why get a multimeter
« Reply #8 on: February 11, 2010, 12:16:04 pm »
You could buy a Fluke scopemeter  ;).
Why spend money I don't have on things I don't need to impress people I don't like?
 

Offline xani

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Re: Why get a multimeter
« Reply #9 on: February 11, 2010, 02:18:12 pm »
Digital scope ( i <3 my Rigol ) is also good when u do digital circuits, it can be used as simple logic analyser for serial data (righol have version with LA but imo its way too expensive, i'd rather buy separate one). If i'd have to choose i'd get Rigol and some el cheapo multimeter (i mean those 20-30$, not those 2-3$ ones they are utter crap

As for me i have Rigol DS1052 ($404 from DealExtreme, can't find anything better new in that price range, tho some ppl say support is crap... but then noone was complaining their rigol broke) and Ronex/Velleman DVM 1200 meter ($72 USD new, it isn't fluke, but good enougth for me)
 

Offline StephenOng

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Re: Why get a multimeter
« Reply #10 on: February 11, 2010, 03:17:42 pm »
I noticed that dealextreme also sells Fluke 17B for USD $92. It seems like a good basic meter for electronics hobbyist/engineer. It has a basic DC accuracy of 0.5%. It is however an odd Fluke model as it is only targeted for China market.
 


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