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What to look for in a Multimeter

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John Loftus

John Loftus

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I'm in the market for a new multimeter. Any suggestions on what to look for?

Get technical if you need to but I may not be able to follow along too far i.e. no formal background in things electrical /bcforum/images/%%GRAEMLIN_URL%%/grin.gif

Thanks,
John
 
I am not very electrical savy either. I purchased an inexpensive multimeter {Power Raft DT-830B} from either Cal Ranch or True Value {I can`t recall which} for around $5.00. It tests Ohms, Volts and Amps and even has a socket to test something or the other {looks like a socket to test transistors of some sort}. It works great for my purposes. {testing voltage, testing for continuity, checking small bulb filiments and fuses for open circut ECT.} I have a high end Fluke multimeter that I hesitate to use for fear of connecting it to something wrong and frying it, so I got this one, if it gets fried, whats 5 bucks /bcforum/images/%%GRAEMLIN_URL%%/lol.gif

Note: I built a 60 Ft. triangular shaped crank up Ham radio tower {60 Ft. fully extended and 25 ft. retracted} for a friend for $200.00 and the fluke multimeter.
 
Hi John,
I have an old (35 years) Simpson 260. I also have a couple of digital meters. I much prefer the 260 for almost everything. Being analog, it isn't subject to the flakey readings that you often get with the digital. It is much more rugged & heavier. It's even internally fused, added feature, so that it isn't destroyed if you happen to have it on ohms while checking volts. It does stay put when you are working with it. The light digitals tend to slide all over the bench or car when pulling on the test leads.

It will actually read three ohm ignition coil primaries accurately. Most digitals won't read low ohms accurately at all.

I've seen 260's offered for bargain dollars on Ebay. I'll bet if you looked around, you could find one.
D
 
Dave Russell said:
It will actually read three ohm ignition coil primaries accurately. Most digitals won't read low ohms accurately at all.
Click to expand...

You must have read my mind! I purchased a correctly date stamped Lucas coil from someone who said it measured 3ohms and both my el cheapo (one digital and one analog) meters come up with about 6 Ohms (the same as my other correctly stamped coil). So I need to get to the bottom of this. Thanks for the recommendation.
 
I'd prefer a used Fluke to just about anything else. Check eBay. I have half a dozen meters and the Fluke is the first one I reach for. It has true RMS and is "autoranging" (you dont need to set the scale manually).

For a "value priced" meter, check the Triplett line. I have a Triplett 9000 series that I keep in the garage. Works fine, was about $50. I also keep a $5 Harbor Freight yellow jobbie in each car just in case. They're fine for testing resistance and voltage, just dont expect too much from it.
 
Dave Russell said:
I have an old (35 years) Simpson 260
Click to expand...

There seem to be a couple of types of these Simpson 260 meters on eBay. Do you know which you have (I saw series 4, 5, 6, 7, 8p). Someday soon I want to add a better meter to my kit, and I'm a big fan of analog for such things.
 
It has the ability to zero the ohms on any scale which takes any error due to lead resistance, contact resistance, or battery voltage changes. This is especially important on very low ohms. It takes a rather expensive auto ranging digital to be able to do the same. Cheap auto ranging digitals are hopeless on low ohm readings.
D
 
Old Trip model 630 here, along with a couple other analog ones. The trip is a Bakelite (!) case unit, bigger'n a house-brick, heavier too. Likely as old as me. Still the "meter of choice" when I'm doin' aught electrical/electronic. /bcforum/images/%%GRAEMLIN_URL%%/wink.gif
 
Thanks, Dave. Any excuse to add another tool to my inventory is always welcome. /bcforum/images/%%GRAEMLIN_URL%%/grin.gif
 
Hello John,

excuse me if I'm teaching you to suck eggs, but just be aware of the significant difference between setting up to measure voltage and amperage. With the former the meter goes across what you need to measure, and with the latter it is connected in line.
The danger is that you try and measure voltage forgetting the meter set to read amps, this presents a near dead short to what you are trying to measure, and depending on where you are checking depends on the size of the spark and tests the meters inbuilt protection. (This can be really hazardous when using a multi meter on mains voltage, especially in the U.K. where our mains is twice the voltage of yours.)

Alec
 
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Mine is a series 5. Rugged old brute, still looks & works like new.
[/QUOTE]

DITTO, Dave!!! Really want to know how "rugged"?? /bcforum/images/%%GRAEMLIN_URL%%/devilgrin.gif

A number of moons ago I worked as a two-way radio tech (hence the 260 /bcforum/images/%%GRAEMLIN_URL%%/grin.gif ). Some of our work included installing/checking antenneas on TOWERS. I dropped mine from 150' (in hard leather case but open) and it still works just fine (tested vs 2 others in shop =ed identical readings).

Can't beat them to death!! /bcforum/images/%%GRAEMLIN_URL%%/devilgrin.gif

/bcforum/images/%%GRAEMLIN_URL%%/cheers.gif
Ed
 
Thanks for the all the advice. I picked up a Simpson 260 series 5 on ebay for about $30 (including shipping) and it arrived yesterday and is in fine shape.

Both original coils tested out at 3.2 ohms so they appear to be keepers.

One thing I'll keep my eye out for is a leather case. Not that I'm planning on scaling any radio towers in the near future but it would be nice to keep it protected.

Battery question .. is there a concern with keeping the batteries installed for an extended time because of corrosion?

Cheers,
John
 
Features that I would recommend:

1). A audible continuity test. This is invaluable when trying to identify wires in different locations of the car. You don't have to see the meter face to know if you have continuity (a short). The meter beeps at you.

2). A rubber protective "boot" that fits over the back of the meter. Not sure the correct term for these but most major suppliers offer them. Meters tend to get knocked around a lot when in use and these things are very effective in protecting them.

3). If the meter doesn't come with them buy some alligator clip leads or lead ends. You only have two hands and one of them will probably be cradling your new meter. Allgator clips free up those hands to do other stuff while your taking measurements.

I bought a digital TPI 153 (from Digikey) about 10 years ago for $85 and it has served me flawlessy since. That same meter sells for about $75 today and has a couple additional features.

Greg Oakes
 
John Loftus said:
Thanks for the all the advice. I picked up a Simpson 260 series 5 on ebay for about $30 (including shipping) and it arrived yesterday and is in fine shape.

Battery question .. is there a concern with keeping the batteries installed for an extended time because of corrosion?
Cheers,
John
Click to expand...
I haven't noticed any good quality dry cell made in the last 10 years having a leakage problem.
D
 
Hi Dave,

I did discover a leaking dry cell just recently but it was some off brand type that came with the product from the overseas factory. I have new Duracells in the Simpson so I guess I'll be set for some time. Thanks for all the info!
 
I have been waiting for someone to say this, but they haven't so I will! In my mind, the most important thing is the ability to measure large current, up to say 20 or 25 amps. Most small or cheap multimeters won't do this.

The other point which arose for me was that a digital meter gives stupid answers when what is being measured is varying rapidly. I wanted to measure the average field current of the third-brush generator of my 1925 Rover, which varies through the rotation of the armature, and found that while an analog meter gave sensible results, my digital one just went wild.

Ken G, 1925 Rover 16/50 (San Francisco)
 
For folks who are inclined to experiment a bit, it's not hard to convert a voltmeter to read amps.
The Simpson model 260, already has a direct ammeter function up to 10 amps.

Almost all ammeters are actually shunted voltmeters. A quick internet search shows that there are many ammeter adapters still available for the Simpson 260 & other multimeters, new & old.

A simple approach to making a 25 amp meter would be to connect a 4.6" length of 16 gage Ni-Chrome wire to two banana plugs, (a shunt) insert the plugs with Ni-Chrome wire into the meter inputs, & plug the test leads into the backs of the banana plugs. With the meter set on the 2.5 volt scale, the meter will read zero to 25 amps.

The calculations:
Required shunt resistance = 2.5 volts divided by 25 amps = 0.1 ohms.

Since 16 gage Ni-Chrome wire has 0.2595 ohms resistance per foot;
0.1 ohms times 12" divided by 0.2595 ohms per foot = 4.6" of wire needed.

The required wattage for the shunt at full current would be 25 amps times 25 amps, times 0.1 ohms = 63 watts. the 4.6 inches of Ni-Chrome wire will easily handle 63 watts.

While this adapter would not give lab accuracy, it would be fine for general purpose measuring.

There are many combinations of meter scales & shunt values that could be used.
D
 
Dave,

I would watch out for using Ni-Chrome wire for shunting a connection. Nice short story to exemplify this, I'm working on a research project putting a pico sat into space with a stage rocket. The primary ignition source for the 3rd stage of the rocket is..... Ni-Chrome wire.

I know that the wire has a specific resistance per foot, but if you happen to knick it by accident that's going to cause a connection that might heat up quite fast. It's a sight seeing (or hearing) that stuff pop for the first time.

Instead I would recommend a high wattage current sensing resistor in series with your load and then measuring the voltage across it.

But, in all honesty, if you are going to be consistently measuring high currents, get a high quality bench multimeter. We use some nice Agilent (34055A variant) models both for my research and at my office (lab). I understand these models go for roughly $1000 new, but a somewhat older model can be found used for significantly less at the right time. Additionally, the connectivity for logging on these guys is amazing for a range of uses.

Now, in a hand held model, in my surface mount lab we have a crafstman model which fits in my hand. The three most used functions I have on there are the DC voltage, DC current, ohms (and connectivity WITH BEEP) and temperature. Make sure the hand held unit you get has temp.

Right now I have a cheap harbor freight unit in my garage for dirty work, but I'm on the lookout for a handout bench agilent. Additionally I plan on getting a decent quality handheld unit too.

In response to the idea of using an analog meter over a digital one, I somewhat disagree (only somewhat). Although a cheap digital meter might jump all over the place while the needle of a analog meter will appear to stay consistent, that's only because the needle physically can't keep up with the inconsistencies and because the needle is usually just that inaccurate. What you can do to fix this is buy a unit with two features. First, the ability to change the number of significant digits, second, the ability to set the averaging time. Therefore, the measured value will only change over a certain delta t. That way you won't have big jumps while measuring.

Finally, I have to recommend a mid range handheld unit for garage work with the above features and a real bench unit in conjunction with 2 GOOD power supplies for more accurate work.

Hopefully this all makes sense,

Ben
 
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