digital multimeter...........

[poprockcrusher]

the Fluke 87 is also known as GM special tool J6360
I have had mine for almost 20 years

 

[Michael]

By cutting the strands, you aren't changing the resistance of the wire, just the ability of the wire to carry current. Your test will never show the difference you are looking for.

I'm pretty sure the resistance changes when there is only one small strand. I'm just saying that hand held meters are not accurate enough to pick up the change. It would be like taking a two inch hose and putting a 1/4 coupler in the center of it, it's going to cause resistance.

 

[walrus]

I'm pretty sure the resistance changes when there is only one small strand. I'm just saying that hand held meters are not accurate enough to pick up the change. It would be like taking a two inch hose and putting a 1/4 coupler in the center of it, it's going to cause resistance.

Yes, but the multimeter doesn't load the wire and you wouldn't know if the hose had any resistance unless you open the valve. Put current on the one strand and your analogy makes sense.

 

[Michael]

Yes, but the multimeter doesn't load the wire and you wouldn't know if the hose had any resistance unless you open the valve. Put current on the one strand and your analogy makes sense.

All a meter does when it measures resistance is send current through the wire and measure the voltage drop. So it is putting a load on it, although small.

 

[MrMark]

By cutting the strands, you aren't changing the resistance of the wire, just the ability of the wire to carry current. Your test will never show the difference you are looking for.

He most certainly is and current is inversely proportional to resistance. V=IR. I=V/R. Can't diagnose anything without understanding this.

 

[MrMark]

All a meter does when it measures resistance is send current through the wire and measure the voltage drop. So it is putting a load on it, although small.

Yes, of course. This point is not directed at you, but water and electricity analogies are not useful.

 

[caper]

It puts current through the wire but not nearly enough to be able to tell if you have one strand of wire or not.The amount of current put out by a multimeter won't overwhelm one strand of wire.Most only put 3v out on an ohms test.Something like a teslite would be more helpful.
http://www.amazon.com/dp/B002QK45XK/?tag=atomicindus08-20

http://www.brighterideas.com/pdf-files-for-everything/TESliteae-Manual-V3.3-GEN.pdf

 

[Stick]

He most certainly is and current is inversely proportional to resistance. V=IR. I=V/R. Can't diagnose anything without understanding this.


Edited: to correct relationship due to a momentary lapse of reason.

Think about it, by cutting strands of wire, you cut down on the available paths for electrons to flow through the wire, reducing the amount of current that can flow through it.

If you are going to quote formulas at me, you might want to understand them. If you re-read what I stated: "the resistance doesn't change, just the ability of the wire to carry current", you'll see that Ohms law will verify what I just said. If the resistance stays the same, and the ability to move current drops, it will lower how much voltage can flow through the wire before it melts. Just like in the real world.

Look up the formula for power.

 

[MrMark]

If you are going to quote formulas at me, you might want to understand them. If you re-read what I stated: "the resistance doesn't change, just the ability of the wire to carry current", you'll see that Ohms law will verify what I just said.

If the resistance stays the same, and the voltage stays the same, the only thing that changes is how much current can flow through the wire. By cutting strands of wire, you cut down on the available paths for electrons to flow through the wire, reducing the amount of current that can flow through it.

Resistance is proportional to wire lenght and inversely proportional to cross sectional area. Going from memory the formula is something like R = Rho (coefficient of resistivity) * A * L.

Fatter wire has less resistance.

 

[MrMark]

It's R = (rho * l)/A.

I just looked it up. R is inversely proportional to cross-sectional area. As the cross sectional area increases the resistance goes down.

 

[MrMark]

Think about it, by cutting strands of wire, you cut down on the available paths for electrons to flow through the wire, reducing the amount of current that can flow through it.

And what do you think that does to the resistance. If you have more current, you have less resistance, if Voltage is held constant.

 

[MrMark]

Think about it, by cutting strands of wire, you cut down on the available paths for electrons to flow through the wire, reducing the amount of current that can flow through it.

If you are going to quote formulas at me, you might want to understand them. If you re-read what I stated: "the resistance doesn't change, just the ability of the wire to carry current", you'll see that Ohms law will verify what I just said. If the resistance stays the same, and the ability to move current drops, it will lower how much voltage can flow through the wire before it melts. Just like in the real world.

Look up the formula for power.

Try editing again. No better this time. First of all Voltage doesn't flow. It exists as a potential difference between two points. Current flows. "The ability to move current drops" What does this mean? Sounds like you are trying to say the resistance increases.

 

[Teken]

I don't know why every thread has to end up in a ******* contest but. This is my two cents on the topic and take it for what it's worth.

Given the jump in technology far and wide even a cheap $25.00 DMM will give you the accuracy that you're looking for. Now if you're addressing CAT rating the cheaper one's do not meet those safety ratings, nor are they built and designed to shield the unit from EMI / RFI which in my case is important in an industrial setting.

When people are talking about voltage drop and resistance. One thing to keep in mind is that unless it is in the extreme ranges even a cheap meter can display the nuts and bolts of what you need to know . . .

Now would I use a $25.00 DMM for work? No, but in a pinch in daily random affair no problem, comes down to how important the information you need to know.

If we are talking about zener diodes etc and you need accuracy to ensure that the break over point is set correctly for what power supply you're designing. I can assure you that $25.00 meter will get you to the ball park, but it sure won't get you to where you need to be if accuracy is what you're after.

Just some insight before this thread gets off base . .

 

[doug.j]

You get what you pay for. I don't have a need for a cheap metersbut I'm sure they fit the needs of some. Same with other tools. Here's a few videos that discuss very cheap meters and a few Flukes.

http://www.youtube.com/user/EEVblog#p/u/79/8cNc5An0DLw

http://www.youtube.com/user/EEVblog#p/u/72/whvSl_0p8e4

http://www.youtube.com/user/EEVblog#p/u/8/vkYm021p5qk

http://www.youtube.com/user/EEVblog#p/u/6/qlA7-fh5nDQ

 

[Stick]

Try editing again. No better this time. First of all Voltage doesn't flow. It exists as a potential difference between two points. Current flows. "The ability to move current drops" What does this mean? Sounds like you are trying to say the resistance increases.

I'll own this one and admit you are correct, I can see where I didn't think through what I was saying. I think Caper was able to sum up the point I was trying to make.

Because the wire isn't loaded, the meter can't tell the difference between a 22g wire with one intact strand and a 4/0 wire with all of the strands intact. To the meter, the wire is the same, even though the overall resistance of the wire is much higher with the strands cut. Most meters aren't sensitive enough at the extreme low end of the scale, so tests like Michael was describing aren't a good indication of if the meter is accurate or not.

 

[MrMark]

I'll own this one and admit you are correct, I can see where I didn't think through what I was saying. I think Caper was able to sum up the point I was trying to make.

Because the wire isn't loaded, the meter can't tell the difference between a 22g wire with one intact strand and a 4/0 wire with all of the strands intact. To the meter, the wire is the same, even though the overall resistance of the wire is much higher with the strands cut. Most meters aren't sensitive enough at the extreme low end of the scale, so tests like Michael was describing aren't a good indication of if the meter is accurate or not.

You get credit for fessing up. I was hoping you would do that.

Now, as to whether the wire is "loaded" is not a good way of looking at things and will only harm your ability to understand. I have no idea what "loaded" means.

The important factor here is the meter's resolution. If the meter is able to resolve milliohms then the meter is able to resolve milliohms. You look at the resolution and the accuracy of the meter. Pull up your meter's spec's and compare it to the anticipated range of resistance of the wire. If the subject wire is within your meter's resolution, then you can get a good reading.

 

[Stick]

You get credit for fessing up. I was hoping you would do that.

Now, as to whether the wire is "loaded" is not a good way of looking at things and will only harm your ability to understand. I have no idea what "loaded" means.

When I realize I'm wrong, I'll own it. You'll never learn anything if you can't admit you make mistakes once in a while.

Loaded to me means that the wire (or component) is in the live circut. In this case, if you pull the wire out of the circut it may test good due to the inability of the meter to resolve resistance measurements that low. However if you put the wire into the circut, it will not be able to pass current the way it was intended. Now if you were to measure voltage drop on a live circut, you would see that the wire is bad, even with a cheap meter.

I'm not a rank amateur when it comes to electricity, but I think I got caught up trying to explain something and was trying to wrap a not quite solid understanding around my explanation. I guess it's time to hit the books again for a little bit.

 

[20-100]

Fluke is the way to go...

I still have my Fluke Model 23 (it's discontinued but as long as I'll be able to have it calibrated I'm not changing it).

I have it since more than 15 years, it was seriously abused... dropped from scaffolding, dipped in water, overloaded (thanks god for the internal fuses), etc... and today, it's still looks good and works well.

The actual equivalent model is the 27-II.

 

[Sick Puppy]

Okay, so if I'm looking at a fluke multimeter, in relation to working with cars, is the 87 model the only way to go? I looked at the fluke site, and cars weren't an area they referred to... are they much of a muchness, or is there a particular type I should be looking for?

 

[Busted_Knuckles]

Okay, so if I'm looking at a fluke multimeter, in relation to working with cars, is the 87 model the only way to go? I looked at the fluke site, and cars weren't an area they referred to... are they much of a muchness, or is there a particular type I should be looking for?

You missed my post on page two:

Re: digital multimeter...........

--------------------------------------------------------------------------------

I see the Fluke 87 is popular, not sure how I wound up with the 88 Model, I thought the 88 was the automotive meter from fluke? Anyhow, I bought mine new, use it weekly if not daily, and like it, Ive used other techs from time to time, and found that I really like mine after using others. This is what I found online about my meter:

The Fluke 88V has improved measurement functions, trouble-shooting features and accuracy to solve more problems on conventional and hybrid vehicles. The 88V is the most powerful automotive multimeter Fluke has ever offered. In addition to having all standard multimeter features like the ability to measure voltage, current, continuity, and resistance, the 88V can perform diode test and pulse width measurements.

This meter can take current measurements up to 20A for 30 seconds and 10A continuously. The optional magnetic hanger lets you attach the meter to almost any steel surface for easy set-up and viewing. The 88V is designed to be used in high energy environments like those found on hybrid vehicles.

 

[comedyman809]

get a fluke with only what you need it for,

im and eletrical tech...i use.....AC DC AMPs and continuity and the ohm meter, thats all.

so get the one with what you use. some have an ampmeter as part, and some dont, then you use a separate amp meter.

i have many meters. but my new fav is the fluke t5-1000, its an amp meter, ac/dc voltmeter, and ohmeter with continuity. all i need. stick with fluke though. although, amprobe makes an excellent amp meter, it also hase a multi meter with a thermometer....i was a refrigeration guy when i used it, and that helped a lot. dont get the one that looks like a computer if yu only need ac and dc volts!

 

[comedyman809]

i beleive nec states that after 50 foot of wire run, there is a risk of a a voltage drop, and nec allows no more than 3% or voltage drop, and the reccomend that if the run is going to be over 50 feet, that gauge should be 1 size bigger. that means the wire will be fatter, and the resistance will be smaller.

correct me if im wrong. so thickness does matter.

 

[Sick Puppy]

You missed my post on page two:

Re: digital multimeter stuff[i/]

Nah, I got this, but I was wondering if that was the only model, or if there were others... I looked on the fluke website, but couldn't find the automotive section (as I figure there isn't one! lol)- cheers for the reiteration, I'm now looking for the model on the site specifically... Cheers!

 

[Busted_Knuckles]

Okay, so if I'm looking at a fluke multimeter, in relation to working with cars, is the 87 model the only way to go? I looked at the fluke site, and cars weren't an area they referred to... are they much of a muchness, or is there a particular type I should be looking for?

I added a pic of mine in my previous post (you can see at the top of the meter is printed "Automotive"), something worth mentioning, that meter does have a high/low/average function. So you can set it, and it will record the high, the low, and the average from a time period you specify, I use that frequently. It will also measure frequency and pulse width. I'm not sure about the other families of meters (as far as the size of the plug on the leads that goes into the meter), but there is an aftermarket of accessories, leads, clamps and so on, I'm not sure if that is the case with other manufactures. Ive got a small tool box for my meter and almost all my accessories are aftermarket (spelled affordable!).

 

[Sick Puppy]

I added a pic of mine in my previous post (you can see at the top of the meter is printed "Automotive")

[...]

Ive got a small tool box for my meter and almost all my accessories are aftermarket (spelled affordable!).

lol cheers for that, and thanks for the additional info!

 

[Sick Puppy]

Okay, after a few weeks of looking around, a Fluke 87 is out of my budget for what I want... what other brands should I be looking for?

I want it mainly for automotive work, notably a reshell project- moving running gear into another car, and checking components before and during this project, as well as diagnoostic work. As for other work... [shrugs]

I don't really want to spend more than about US$70. Would be nice to be able to have it calibrated, but then, at that kind of price I think I'm pushing it! lol

So, any suggestions?

 

[Sick Puppy]

Re: last post, I'm now hovering a lot closer to the Flukes or other better brands - the **** Smith / Jay car ones are pretty much regarded as junk, the Uni-T ones okay but not much better... looking overseas now and trade shops... I think this is going to be expensive! lol

 

[PrecisionTools]

Check out

He also does a shoot-out on $50 dollar meters. I would suggest you go through some of his vids on meters because you will learn a bit about them and he has an Australian/NZ perspective.

My advice on Fluke? 87 series is way above what you need for general automotive work. I have always used the entry level Fluke meters and still have the first one I bought (Fluke 12) 22 years ago. It was limited as I moved into engineering so I have upgraded (Fluke 112) but still find myself going back to my old one every now and then.

I think if your buying new then the Fluke 115 would be a good buy. I would go up to the 116 to get better low current measurement but I really don't think you need it. Have a hunt around for this model and see if you can get a price within your budget. Haggle!

If you are in no hurry, keep an eye on ebay for a second hand 70 series. They are getting on a bit but are tough as nails and with a new set of leads and a clean up you will have a tool that will go for ever.

Hope this helps

 

[LawnDart79]

If I were you, I'd take a look at the Fluke 77 IV. For the average guy, this meter will do everything you ask of it.

Is the 77 IV my 1st choice of meters, no, but that doesn't make it a bad meter to own. I wouldn't be afraid to use one if I needed to. I personally own a Fluke 88.

Finally, often times these meters can be bought used from ebay and such for $75-$100.

 

[Krokodil]

I bought a used Fluke 177 last week for 1/4 of the new retail price. Pretty chuffed with myself!

 

[kms]

I got a Fluke 87-III off ebay for $30. Had a blown fuse, replaced it, good as new.

 

[0.511MeV]

Check out B&K Precision. They make a mighty fine meter for the price. I think most of them are about 100 USD.

Sure, I love Fluke, but B&K is my next bet for a lot of stuff.

 

[98TJ]

Since '95 I've been using the Fluke 75. Still serves me well.

 

[PrecisionTools]

I read on another forum that Rexel is having a Fluke sale - getting out of the brand apparently. It looks like they have a few shops in Christchurch - http://www.rexel.co.nz/index.php/pi_pageid/4 Give them a call and give them heaps...

 

[Bigpigdave]

I have Fluke 87 and 112. I use them both a lot. I also have several accessories that make them even more useful.
Dave

 

[Sick Puppy]

I read on another forum that Rexel is having a Fluke sale - getting out of the brand apparently. It looks like they have a few shops in Christchurch - http://www.rexel.co.nz/index.php/pi_pageid/4 Give them a call and give them heaps...

Thanks for the heads up - you're all quite right of course, a Fluke is massive overkill for my knowledge and needs, but if I get one for an awesome price... I'll see what they've got!

 

[Danglerb]

Meter in my toolbox that served me well for a good 20 years cost me $6 new at Radio Shack. It is a simple analog meter, which means it draws too much current even in the volt mode to be used with computer type signals, but it still worked fine for most diagnostic work where supply voltages are what needed to be checked.

Fluke makes a great meter, but nobody outside of the trade needs anything that stands up to as much abuse as a fluke. They are made to be used by employees that don't pay for their own tools, and electronic things need to be pretty robust in the hands of a person who doesn't pay for a replacement. I've never dropped a meter, maybe never will. I have blown up a couple, and since I was holding it in my hands at the time the lesson of what not to do eventually stuck.

Anything that works and I am good to go, with the only features I have been willing to pay for being a large easy to read display, and some automotive functions like tach and dwell (useful on injectors).

OTOH it does strike me as a little funny that I will be using about $100 in various test leads and adapters with no meter more expensive than $27.

*** Don't forget to remove old batteries. My B&K meter got switched on in my toolbag and the Kodak lithium 9v swelled when it died and busted the case around the battery door after maybe 25 years of use.

 

[scott37300]

NJHandyman has a fluke 77 for sale in the classifieds, http://www.garagejournal.com/forum/showthread.php?t=105085&showall=1

 

[mrbreezeet1]

I got a cheapie from Auto Zone that seems OK.
My boss said it wasn't so good cause it's not auto range, but I don't think you really need auto range.
it is this one.
http://www.amazon.com/dp/B0002LZU7K/?tag=atomicindus08-20

 

[back2class]

I have a $60 Actron full feature automotive unit that I got it as part of a tool lot. I also own a few $5 HF digital units. Guess what? I almost never use the big Actron. For the basic functions I use a meter for the HF works great and I don't worry about it getting fried. I use a multimeter only every few weeks though. I have had 2 nice flukes and a Matco come across by tool box, but never kept them as my multimeter needs are exceeded by about 1000% with the units I own. Sold them cheap too. I think $75 each for the fluke 87's I think and $30 for the Matco. I believe the $20 Craftsman one that goes on sale for $10 sometimes is all most of us here will ever need.