Author Topic: EEVblog #489 - Agilent 34461A Multimeter Review  (Read 29735 times)

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Offline c4757p

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Re: EEVblog #489 - Agilent 34461A Multimeter Review
« Reply #75 on: June 30, 2013, 04:00:46 pm »
Well, you get the warm-up time of the ADC, but aren't you neglecting the reference by doing it at zero?
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Offline AlfBaz

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Re: EEVblog #489 - Agilent 34461A Multimeter Review
« Reply #76 on: June 30, 2013, 04:16:52 pm »
according to lm399 data sheet, it take 3 seconds to warm up. I always though the warm up time was to get "everything" up to operating temp were the tempco's of all passive and active devices have had time to plateau and any thermoelectric differences have reached some sort of stable point, as its at this point that calibration was done
 

Offline mikeselectricstuff

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Re: EEVblog #489 - Agilent 34461A Multimeter Review
« Reply #77 on: June 30, 2013, 05:05:25 pm »
A nice use of Trend Plot is to identify your meters actual warm up time by shorting the inputs and turning the meter on and instantly turning on trend plot in DCV. The chart will show the Logaritmic? warm up curve and you can determine visualy what your meters actual warm up time is instead of using the manuals generic time. On my 8846A I find it is about 30 minutes instead of the stated 1 hour. I would guess the 34461A would be similar.
surely all that will tell you is zero drift, not absolute voltage reference stability
 
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duskglow

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Re: EEVblog #489 - Agilent 34461A Multimeter Review
« Reply #78 on: June 30, 2013, 05:22:29 pm »
surely all that will tell you is zero drift, not absolute voltage reference stability

How would you tell absolute voltage reference stability?  And don't call him Shirley.
 

Offline mikeselectricstuff

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Re: EEVblog #489 - Agilent 34461A Multimeter Review
« Reply #79 on: June 30, 2013, 05:31:02 pm »
surely all that will tell you is zero drift, not absolute voltage reference stability

How would you tell absolute voltage reference stability?  And don't call him Shirley.
With a stable external reference.
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Offline free_electron

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Re: EEVblog #489 - Agilent 34461A Multimeter Review
« Reply #80 on: June 30, 2013, 06:45:54 pm »
Why wince over others ? Because they ru. ST' spear processor.
Agilent made a win ce port for that cpu. They use it in their scopes. So they have a huge ecosystem inside the company already...
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Offline robrenz

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Re: EEVblog #489 - Agilent 34461A Multimeter Review
« Reply #81 on: June 30, 2013, 11:45:02 pm »
Well, you get the warm-up time of the ADC, but aren't you neglecting the reference by doing it at zero?

That sounds right, but I don't know, I'm a machinist not an EE :-//

surely all that will tell you is zero drift, not absolute voltage reference stability

How would you tell absolute voltage reference stability?  And don't call him Shirley.

It's OK, I have been called surely before :D

With a stable external reference.

I never implied anything about reference stability just when does my meter trend plot go zero slope with a invariant input meaning things have settled down and I will now get consistent readings that don't have warmup artifacts.  Whats more stable than a shorting bar?  I don't have anything to give a 10V signal that varies less than 1µV, who does?

Just a few captures showing what I was talking about and how nice it is to have trend plot on a meter.  8846A with shorting bar in inputs, DCV auto range, 100NPLC, digital filter, trend plot as soon as it boots. 6 min. 20 sec has passed. 1.2172µV droop including noise.


Same setup at total elapsed time of 28 mins. 1.7184µV droop including noise.


Same setup at total elapsed time of 1 hour 18 mins. 1.7542µV droop including noise. Only 36nv additional droop/noise. Obvious that the 28 minutes is enough time that the meter is stable.


Same setup but meter is now zeroed after the 1 hour 18 mins. and back into trend plot to see general noise.  465.4nV total span of all readings over 6 minutes. This correlates well with the noise level seen in the 1hr 18 min plot above.
« Last Edit: June 30, 2013, 11:47:45 pm by robrenz »
 

Offline ElectroIrradiator

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Re: EEVblog #489 - Agilent 34461A Multimeter Review
« Reply #82 on: July 01, 2013, 04:00:38 pm »
I've built countless mobile production and service test jigs. Most of them that require gear such as this (i.e. high end/high precision) will inevitably have a PC based control and logging system on the trolley as well. So the boot time of the PC and program usually dominates.

Not an expert, have just seen what others have built. Those I've seen has used laptops to get around the rebooting and setup problem. Though I am aware that a laptop will not cut it in every situation (if you absolutely need PCI cards etc.), and the UPS idea may also have merit.

That's what hand held meters are for. Or a bench meter without such high end system functionality that is instant-on.

And that's the kicker. This a complex system multimeter with oodles of power and functionality, it is not designed for the push-on and take a simple measurement crowd.
If any buys it for that and them proceeds to complain about the boot up time, then they are being rather silly.

Several years ago, while I was still active in my particular field, a colleague once asked an Agilent rep if the general kind of activity we engaged in was important to Agilent from a business perspective. The answer we got at the time was a strong affirmative.

As alm mentioned, then the 34461A is positioned to be the successor to the venerable 34401A, which I used regularly back then. I would expect it to be able to perform all the duties of the 34401A if this is so, and some of the basic needs we had to a 'field' DMM were:

*) Mains powered, with no batteries to run out. We frequently ran our DMMs for half a day or more at a time, sometimes with no say in the matter!
*) One man portable, relatively quickly if possible. We'd have hauled 19" rack gear around if that is what it took, but the smaller size of the 34401A was great.
*) Easy to stack physically, both vertically and horizontally.
*) High visibility display. In this regard I personally much prefer the VFD displays to, say, the 7 segment LCD display on my Fluke 189 (Mk I).
*) High relative accuracy, 5 digits didn't always cut it. Whenever possible our test/monitor points were designed such that absolute accuracy wasn't needed. By this I mean we only needed to see whether we could hit a null through adjustment, or quickly be able to check if a test voltage drifted and if so, gauge the speed and direction of drift. [1] My colleagues and I are acutely aware of the problems involved in obtaining measurements with an absolute accuracy in the uV range, so we mostly didn't even try.
*) Remote control and data acquisition was occasionally useful.

While we obviously didn't need all of these points fulfilled simultaneously, we did need them all at one point or another. My colleagues still do, as far as I know.

Additionally, our electronics labs mostly have a support function, they are not the center of activities. By this I mean that the test gear within are tools, which we fetch at need. Sometimes we are able to bring a piece of electronics there to troubleshoot, or we may develop a custom solution to a particular problem, though either didn't happen too often.

I'm terribly sorry if this bothers you but yes, my colleagues absolutely use the 34401A DMMs and their likes as portable devices to be used in the 'field'. They do not stay within the confines of the comfy laboratory.

Care to take a guess at what we do? By your words we cannot possibly have a valid reason to use these DMMs outside the confines of a proper lab, so clearly what we do is utterly pointless. ;)

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[1] "Oooohhh, the 34461A has drift mode! Aww chucks... Takes forever to boot, so no more quickly running around, locating the source of drift...  :'( "
 

Offline SeanB

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Re: EEVblog #489 - Agilent 34461A Multimeter Review
« Reply #83 on: July 01, 2013, 05:33:33 pm »
I saw a cart at CNA ( local bookseller, but mostly a few magazines, cards and romance pulp these days) they use to do stocktake. Has a PC, monitor, keyboard, mouse, mousepad, barcode scanner and a thermal printer all on it. Connected to a 50m long extension cord and a 50m long ethernet cable for the data connection. Reason fo this is Head office says they must take the stock to the computer to stocktake, and with 10 000 items in the store, often in quantities from 1 to 100 it would otherwise take weeks. With this it just takes a day every month.
 

Offline ElectroIrradiator

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Re: EEVblog #489 - Agilent 34461A Multimeter Review
« Reply #84 on: July 01, 2013, 09:17:59 pm »
Why wince over others ? Because they ru. ST' spear processor.
Agilent made a win ce port for that cpu. They use it in their scopes. So they have a huge ecosystem inside the company already...

Then my question reduces to why Agilent chose WinCE for the 2000X/3000X/4000X scopes? ARM, the CPU core in the Spear, is also a supported architecture for QNX. From what I am being told, then, when compared to WinCE, it is a fair bit more comfortable porting QNX to new hardware. Particularly writing drivers should be a better experience, as a buggy driver won't crash the microkernel. Admittedly I haven't tried this myself though.

I saw a cart at CNA ( local bookseller, but mostly a few magazines, cards and romance pulp these days) they use to do stocktake. Has a PC, monitor, keyboard, mouse, mousepad, barcode scanner and a thermal printer all on it. Connected to a 50m long extension cord and a 50m long ethernet cable for the data connection. Reason fo this is Head office says they must take the stock to the computer to stocktake, and with 10 000 items in the store, often in quantities from 1 to 100 it would otherwise take weeks. With this it just takes a day every month.

A plain extension cord may very well end up being the chosen solution to my use case, at least for the smaller installations.
 

Offline KedasProbe

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Re: EEVblog #489 - Agilent 34461A Multimeter Review
« Reply #85 on: July 05, 2013, 06:03:28 pm »
I'm comparing with the DM3068 from Rigol.

Does someone know if Rigol is planning a new/updated version of their multimeter in the near future?
I would like a bigger screen on it, more like this Agilent, not a deal breaker but it would be nice.
or they can keep it 'small' but provide a tablet app UI.(over the network)

I don't want to buy a DM3068 and see the new one coming out soon after.

edit: Rigol Sales don't know about any new one with bigger screen so it may be a while before the next one is ready.
« Last Edit: July 08, 2013, 02:59:07 pm by KedasProbe »
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Offline ddavidebor

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EEVblog #489 - Agilent 34461A Multimeter Review
« Reply #86 on: July 05, 2013, 06:08:39 pm »
Should be great!
Davide Bortolami,
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Offline KedasProbe

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Re: EEVblog #489 - Agilent 34461A Multimeter Review
« Reply #87 on: July 06, 2013, 04:23:29 pm »
About the Rigol 'wrong calculated' Vrms I checked it with my DG4102 and it's simple, it doesn't calculate it wrong, it doesn't calculate it at all, all arb are assumed to be square waves. so 1Vrms is just 1Vp  ::)

Dave, will you also review the other multimeters you compared it with? (especially DM3068)
I liked the simple battery voltage tests.
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Offline victor

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Re: EEVblog #489 - Agilent 34461A Multimeter Review
« Reply #88 on: July 11, 2013, 12:50:31 am »
They should have implemented a hold to clear button. UI on these scopes is pretty lame.

My clear button solution simulation -> http://fiddle.jshell.net/Victornpb/HmRA4/show/
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Offline EEVblog

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Re: EEVblog #489 - Agilent 34461A Multimeter Review
« Reply #89 on: July 11, 2013, 03:11:55 am »
Does someone know if Rigol is planning a new/updated version of their multimeter in the near future?
I would like a bigger screen on it, more like this Agilent, not a deal breaker but it would be nice.
or they can keep it 'small' but provide a tablet app UI.(over the network)

I doubt it. It's a pretty new model already.
Only now that Agilent have a big screen meter would the competition likely think about it.
 

Offline EEVblog

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Re: EEVblog #489 - Agilent 34461A Multimeter Review
« Reply #90 on: July 11, 2013, 03:12:42 am »
Dave, will you also review the other multimeters you compared it with? (especially DM3068)
I liked the simple battery voltage tests.

No plans, I don't have them for starters.
 


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