Digital Multimeter

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So it's settled. Consensus has it that The Critic should buy a Fluke 120 Series ScopeMeter as well as a HF disposable multimeter to loan to friends. That should have all the bases covered :-)

Actually, I agree with the view that it comes down to whether it will get much use in the future for other projects. If this is a one time project and all you need is something to tell you 0V or 12V, then anything will do. However, if one knows that they will get significant use out if in the future, then take some time to seek out something you can trust and won't frustrate you during use.

I have used my Fluke 77 for so many projects over the years that I don't ever regret paying a hefty sum for it back in the 80's when I purchased it. It has been used for house wiring, automotive work, diagnosing micro-controllers, etc, over the decades.

To The Critic, one thing to keep in mind especially as you own a Hybrid vehicle, do you think you will ever be measuring some of the higher voltages that you might encounter in those vehicles. At that point safety becomes an issue so you might want a meter that has a bit of a track record. (Heck even 220V makes me nervous.) I'm not sure I would trust my cheaper meters with their skimpy leads even though they supposedly can handle the voltage. Another thing to ask yourself, are you the type of borderline OCD person who, like many on the candlepowerforums, cares if their li-ion battery chargers terminates at 4.20V (nominal) or 4.25 (just slightly overcharged.) If so, then again, you might want to consider something a little bit better than the $5 yellow/red manual range meters.

To everyone else, since this is BITOG where everyone confesses their "stash" collections, here is my current multimeter stash:

Fluke 77
Extech 430
Generic Chinese Fluke clone under the name of Circuit-Test
Agilent 34401A bench meter
Kleton M320 (also can be found sold under the Mastech, Apeco, etc, brands)
(Might be a Radio Shack analogue meter in the collection. Can't remember if I donated that one or not.)

BTW, the M320 is actually pretty good for a disposable/glovebox type multimeter. It is auto-ranging and the one I have at least is pretty accurate when compared against my Fluke and Agilent meters. It's only real downside is that the auto-ranging is slow (but still better than trying to reach for a dial to change ranges when both hands are being used to hold the test leads onto something that requires some finesse, ie surface mount components), limited current measurement capability (400mA max), and the leads are kind of short. But, if you only have $20 to spend on a meter, it's not bad.

Now what's in your multimeter stash?

David
 
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Originally Posted By: JHZR2
Originally Posted By: Donald
As far as a clamp on meter, while I agree they are handy, even more handy is a digital scope with clamp on probe. With it you can pull the fuse for fuel pump, connect clamp around battery cable, crank the starter and see which cylinder is bad as it will take less current than the rest while the starter is going.



I would guess so, but what kindof $$$ are we talking about for that? A DC clamp is $$ enough.

Scopes I thought were on the order of thousands of dollars... May be wrong though.


One can get a decent digital scope for a few hundred and the clamp-on probe is maybe $100. If you go for a fancy Tektronix then maybe a grand or two. Unless you are GM building an ECM for a new vehicle, you do not need a Tektronix.

I guess The Critic would need a Tektronix however.
 
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how many channels on that scope? please give few pointers. I would not mind getting my hands on a digital scope for few hundred dollars but my research indicated that even picoscope which uses my own laptop or tablet costs way more than that. If I can get a standalone digital scope with dual/quad channels for few hundred dollars, I will jump on it.
 
Looks like the going rate on Ebay is from $4300 to about $60, depending on how much capability you want.
 
$400 can buy a pretty nice oscilloscope these days. The Rigol and OWON offerings on Ebay seem to be pretty popular. Check out David L. Jones's EEVBlog website for reviews and tear downs.

Since this thread is about multimeters however, also have a look at mjlorton's channel on YouTube "Solar Power and Electronic Measurement Equipment". There is a wealth of information there for anyone seeking out a multimeter.

David
 
Well, it depends on what you want to do with it.

The max input of 80 volts peak to peak kind of jumped out at me. You may need a 10:1 probe for some applications.

My cheapie dual channel ProTek handheld ( no longer made ) will do 600 volts, iirc.

You can get a lot of handheld scope for $500-600 these days, so it looks like an upgrade may be in my near future.
 
Originally Posted By: dk1604

Now what's in your multimeter stash?

David


Oh, you don't want to know.
It's at least a dozen.
The latest purchase was a VC60B+ Meggar, for when I rebuild my alternator and want to test the windings.

Before that it was some cheap MF47A VOMs I wanted for nostalgia, plus, even if no batteries are in them at all I still can leave it in the trunk and it'll measure volts if I need it.

How often does a remote at work not work well, yet there's no battery tester around? Often. There's always a need for a meter a little more versatile than a single-cell tester, but not pricy enough that I need to worry about it going walkies.
 
Originally Posted By: Vikas
what are the pitfalls of something like this? For under $200, I might take the leap if there are no glaring shortcoming.

Mini-4CH-ARM-DSO203-Nano-V2-Quad-Pocket-Digital-2MB-USB-Storage-Oscilloscope


One of the main things to look at is the maximum sampling rate. In this case it 72MSa/S so, unless you employ repetitive waveform capture and can combine all of the captured waveforms, you won't be able to fully utilize the 72MHz analogue bandwidth of the front end. For example, if you are measuring sine waves and want a nicely rendered representation on your screen (and are not employing repetitive waveform capture), you would want around 10 samples per cycle (can probably get by with 5) so that limits you to 7MHz or thereabouts. Another thing to consider is that your 72MSa/S may possibly be shared among all of the channels so, for instance, if you are using two channels you might only have 36MSa/S on each.

That said, if what you are measuring is within the instruments capabilities, it is really nice having 4 channels (even though two are digital.) Four channels is really nice for debugging things like SPI bus where you need to monitor the DATA-IN, DATA-OUT, CLOCK, and DEVICE-SELECT lines simultaneously. (My apologies to the SPI bus gurus out there. I know that the signal names are really MOSI, MISO, SCLK, and *SS.) The Nano is also portable and compact and sometimes that is everything.

Regarding oscilloscope probes, we almost always use 10x probes since they put less load on the circuit under test than a 1x probe.
 
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Originally Posted By: spackard

Before that it was some cheap MF47A VOMs I wanted for nostalgia, plus, even if no batteries are in them at all I still can leave it in the trunk and it'll measure volts if I need it.


Must admit to having a soft spot for analogue meters as well - especially the nice old ones with the nicely damped meter movements, substantial rotary selector switches, and Bakelite cases (vintage Simpson, Triplett, etc). Analogue meters also display trends in noisy signals better hence the bar graphs on many digital multimeters. Alas, must admit I haven't used one in some time now...

However, I'll take an analogue speedometer over digital one any day.

David
 
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Thanks for those comments! Can you elaborate more on the difference between analog and digital channels of that oscilloscope? Most of my usage would on automotive and household application and will not be in the radio frequency domain. Wouldn't 5MHz be plenty fast for mechanical applications? I will not be able to use it for debugging local area networks such CAN protocol but I doubt if it would be possible to do that even with a much faster and expensive scope.
 
Originally Posted By: Vikas
Thanks for those comments! Can you elaborate more on the difference between analog and digital channels of that oscilloscope?.


I can't say for sure regarding that particular scope but on the HP/Agilent scopes I have used the digital channels are essentially logic analyzer channels that tell you whether a signal is logic high or logic low. Essentially a comparator.

There seems to be lots of reviews of that scope on YouTube. There is 50minute review under title "DSO Quad Review" by the user "stuckinpants". I don't have the time right now to watch it but if you are seriously considering the Nano, definitely have a look at the various reviews. Hopefully some of them elaborate on the software and user interface aspects of the instrument.

Regarding the usable bandwidth, I would imagine it would be fine for 5MHz signals (probably even 10MHz). Should be plenty quick for looking at O2 sensor waveforms and such. Would likely even work for debugging CAN bus physical layer problems as the signalling rate of CAN bus isn't particularly fast (max bit rate of 1Mbit/s).

David
 
Originally Posted By: Donald
If The Critic is still waiting, HF has the red one for free on Monday. No purchase, but you need a coupon. Anyone need a coupon?


Good to know, thanks. I do remember the cashier mentioning that I can get a free multi-meter with my next purchase, but I need to see if I can still locate the coupon/voucher.

Do you know where I can get a copy of the no purchase required coupon for the multi-meter? Thanks.
 
Originally Posted By: The Critic
Originally Posted By: Donald
If The Critic is still waiting, HF has the red one for free on Monday. No purchase, but you need a coupon. Anyone need a coupon?


Good to know, thanks. I do remember the cashier mentioning that I can get a free multi-meter with my next purchase, but I need to see if I can still locate the coupon/voucher.

Do you know where I can get a copy of the no purchase required coupon for the multi-meter? Thanks.


PM me and I will forward the email I got from HF. Use it for a week or two, get the ins and outs and buy a better one. Keep in vehicle or as loaner to friends who make break it or may not return it.
 
Originally Posted By: Vikas
I am shocked to see TheCritic visiting HF store! What is this world coming to?

If you look back on his past threads of a year or so, you will learn that he has stepped off his OEM/Snap On only podium and is venturing into the "gut enough" trials and tribulations. For instance, on someone's beater car he tried Bando belts instead of OEM. His recent use of KYB shocks/struts on his dad's minivan turned out less than favorable.

Unlike other young and dumb know it alls (vs. us old and dumb know it alls), TheCritic has the self esteem to give feedback even when his trials backfire on him. A lesson for all of us.
 
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