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Old 04-04-2013, 06:52   #31
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Re: Multimeters - What Features To Look For.

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Originally Posted by MarkJ View Post
. . . Does to volts and to 10 amps DC.
What more does one need?

It would be nice to find a multimeter under $30 that also has a high amperage measuring feature. Like 100 or 200 or more amps. Then you could check the output of your alternator and any other high amperage devices.

In the past I have used a car battery tester amperage meter that slipped over the electrical cable and read out +/- amps with a swing needle. Not all that accurate but it showed current flow well enough. Having a digital version would be nice.
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Old 04-04-2013, 07:00   #32
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Re: Multimeters - What Features To Look For.

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It would be nice to find a multimeter under $30 that also has a high amperage measuring feature. Like 100 or 200 or more amps. Then you could check the output of your alternator and any other high amperage devices.
Thats why a DC clamp meter is useful as well. You really cant handle that type of current through probe wires

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Old 04-04-2013, 07:17   #33
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Re: Multimeters - What Features To Look For.

Not multimeters, but these little scopes can be a godsend once in a while if looking for data or checking for AC leaks etc..

ARM DSO Portable Tiny Digital Scope DSO201 DIY Kit Nano | eBay
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Old 04-04-2013, 07:26   #34
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BTW... if anyone knows how to actually calibrate these things accurately, I'd like to know....
Easy to calibrate most basic functions on most meters. Most meters just have a small variable resistor (pot) on the circuit board you adjust w a small screw driver. Turn very gently because you can easily break one. You just have to figure out which pot for which function and for most popular meters you can find this online...or by trial and error...just note the position of the pot before you turn it so you can reset.

The more difficult thing may be for you to find a known good reference reading to calibrate against. Techs have this in the lab but Ive used several multimeters to "vote" in the field -- close enough for typical cruiser use.
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Old 04-04-2013, 07:59   #35
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Clamp on DC Amps. As others have said clamp on DC is very handy. For most boat apps you dont need more than 30 amps. Meters that will do this are more expensive than the el cheapos.

A backlit display is nice when you are working down in the dark recesses of a boat. One of my meters also has a nifty little light that illuminates the clamp on jaws.

If you want high end features w out a high end price look at ExTech and Mastech brands. These are certainly not on par w Fluke, but plenty good for typical boater use.

Test probes. I have a seperate little bag of assorted test probes. "mini grabbers" I find esp useful - probes ending in tiny spring loaded clips which you can clamp on to components for testing. Also a larger version using alligator clips. And an assortment of jumpers w small alligator clip ends.
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Old 04-04-2013, 08:25   #36
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As so many here said... You asked what to look for in a DMM

Fluke on the faceplate is the best place to start... They also re-calibrate and provide excellent support. Others are fine but in this case the best is just a bit more money than good ones. So Fluke for me

Oh, and like CharlieJ I do this for a living...

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Old 04-04-2013, 09:01   #37
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Re: Multimeters - What Features To Look For.

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BTW... if anyone knows how to actually calibrate these things accurately, I'd like to know....
I've never had to calibrate a multi-meter. I vaguely recall something about checking the calibration of the resistance test function by holding both leads together. They should reach Zero. If they don't then your meter is off. Measurement of voltages in a DC circuit should be fairly consistent. A True RMS meter will give you the most accurate ACvolt reading, but most inexpesive meters are close enough. A 12 volt battery fully charged should read around 13 volts if its storage capacity hasn't been compromised. If a battery wont charge or when fully charged read 12 volts or under the battery needs to be replaced.
The only intruments I've had to calibrate in nineteen years as an electricianare Hi-Pot testers for testing 15kvolt rated cables, and this I have to send off to get certified.
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Old 04-04-2013, 09:09   #38
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Re: Multimeters - What Features To Look For.

surv-
"Are we the only three people who have had calibration issues with multimeters?"
Nope. In fact I got so disgusted by it that I built a calibration source in a miniAltoids tin. I think you'd have to spend over $100 on a meter that was pre-calibrated, and of course you can send them back to Fluke and others who will do a lab-referenced calibration probably for $50? a shot or more.

But I'm a cheap SOB, so I found a reference circuit and now I have an Altoids tin with two alligator clips coming out the side. If I hook up a meter and it says anything except "10.000" then I know the meter is out of calibration. Yes, the reference standard is supposed to be that tight.

In theory you can take a coin cell or some other "reliable" source, or measure the drop across a diode or scrounge some other voltage reference and still get better than no calibration at all. In practice...the Horror Freight fee meter might as well say "YES/NO" and the rest drifted only about .2v after some years. That's still a difference of opinion on a 12v system.<G>

I just have to explain to the TSA why I have a mint tin with wires coming out of it. Or convince them to cut the BLUE wire.<G>
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Old 04-04-2013, 11:59   #39
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Re: Multimeters - What Features To Look For.

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Originally Posted by conachair View Post
Not multimeters, but these little scopes can be a godsend once in a while if looking for data or checking for AC leaks etc..

ARM DSO Portable Tiny Digital Scope DSO201 DIY Kit Nano | eBay
Yeah. I got this little gem (which I believe is functionally identical) about a year ago. The platform is open (as in "anyone can program", which is different from NMEA-'open' ) so there's also 3rd party software for it. Google "DSO Nano BenF".

What's really great is that the 'BenF' version software permits single-shot triggering, and will record the sample buffer to a micro-SD card, which you can then view and process later. It's been fantastic for capturing transient events in the field, like switch bounces or command streams. Many of us recall that before PCs, digital storage scopes cost thousands.
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Old 04-04-2013, 12:02   #40
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Re: Multimeters - What Features To Look For.

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I've never had to calibrate a multi-meter.
I've never had to recalibrate either. Most important is simply checking. Before you trust a cheaper meter, compare it to a known good one, or measure a calibrated voltage.
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Old 04-04-2013, 12:40   #41
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Re: Multimeters - What Features To Look For.

For calibration (or just to know what the offset is) a precision voltage reference is required. Luckily, they are dirt cheap. Here are two:

http://www.ti.com/general/docs/lit/g...VS022&track=no

LH0070 - Precision 10V Reference - Linear Technology

Other chip makers have similar products.
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Old 04-04-2013, 13:17   #42
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Re: Multimeters - What Features To Look For.

I've been an electrician for 19 years and specialize in control wiring on multi-million dollar mining machines. I own three multi-meters, and each has its purpose. To best identify what you need in a multi-meter you need to understand what each function does, and some of the terms you might come across. If you need one for electronic circuitry troubleshooting you would require a precision multimeter, not the ordinary electricians multi-meter. If you don't solder printed circuit boards for a living, then you need one like the rest of us use.

Multimeters come in many shapes and sizes. I prefer a small version with a built in amp clamp meter. It helps to have several types of leads, the black and red sharp pointed ones and alligator clip style. I also recommend the purchase of a hanging magnet clip if the multimeter you buy have them as an accessory. They really help, unless you are one of those lucky people with three arms. The most important feature you should have is an Auto shutoff. Auto shutoff has saved me countless times, as most digital meters can get turned on accidentally in there storage cases. This feature will guarantee you have a working meter when you need it most. Lastly I would make sure it has a illuminated display feature as you will find most electrical problems leave you in the dark or in a dark area. Some even have an led flashlight built in.

Now, if you come across a True RMS meter, this simply means it has a more accurate AC voltage and current reading capability. This is mostly needed when trying to determine power factor corrections, and usually comes with a logging ability that 99% of you will not have any use for, and they cost substantially more. The general use multi-meters are plenty accurate enough for troubleshooting needs.

I could talk about brands for quite a while, but I would steer you away Fluke. I've owned 5 of them in one year, and found they really don't stand up to humid or direct contact with water. Good Brands that I've used in the past are Ideal, Greenlee, UEI, Sperry, and my favorite Klein. Klein is the most preferred toolmaker of electricians and they make tools exlusively for electricans. I own two Kleins and one Fluke. My last remaining Fluke I use exclusively for over 600 volt testing. Be sure to never use a multi-meter beyond its voltage rating. Most are only good for 600 volts. Chineese no-name brands are usually 500 volts or even 250 volts. Look at your meter now and see what its rated for.

My other two meters are the Klein CL-200 , and the MM-200. The CL-200 is my workhorse. It cost about $50 and has proven to be the toughest meter I've ever owned and extremely waterproof. I work in tunnels all day and most often electrical machinery break down when exposed to water seams (waterfalls). I'm always getting poured on and this meter is a steal at $50. It does everything I need except DC amperage. For DC 4-20mA signals I use the Klein MM-200, and have no complaints. Both have lighted LED screens and all the other Resistance, Continuity, AC/DC voltage, temp probe, diode test, and capacitor test functions as well as frequency and peak testing. Like I said all you will need, and both have the Auto shutdown feature. For $100 you can't go wrong.
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Old 05-04-2013, 10:38   #43
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Re: Multimeters - What Features To Look For.

Interesting, that Klein clamp on appears to be identical in every way to a MasTech meter I have.
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Old 05-04-2013, 11:44   #44
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Re: Multimeters - What Features To Look For.

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Originally Posted by belizesailor View Post
Interesting, that Klein clamp on appears to be identical in every way to a MasTech meter I have.
Plus it's the same as the Radio Shack one I posted, just some cosmetic change:
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Old 05-04-2013, 11:49   #45
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Re: Multimeters - What Features To Look For.

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Originally Posted by belizesailor View Post
Interesting, that Klein clamp on appears to be identical in every way to a MasTech meter I have.
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Originally Posted by s/v Jedi View Post
Plus it's the same as the Radio Shack one I posted, just some cosmetic change:
I assume, like everything these days, they are all make by the same small children in the same asian sweatshop.
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