Talk:Multimeter

Untitled

It would be a nice historical note to add something about the AVOmeter, which was the ubiquitous predecesor to modern electronic multimeters. DFH 09:29:53, 2005-09-05 (UTC)

Meanwhile, here's a nice link. AVO Model 8 MkII with some historical information that I just found in the Richards Radios website. DFH 10:41:56, 2005-09-05 (UTC)

I've added data about AVO, David. If you want to expand, proof, or correct it, please feel free to do so! -- Mikeblas 21:43, 8 January 2006 (UTC)

No Explanation of how it works

No mention of processors.

What processors? "Processors" are not necessary to multimeters. Jeh (talk) 09:57, 27 March 2011 (UTC)

RMS processors and how it works for 'digital processors' . .--Ericg33 (talk) 06:11, 2 April 2011 (UTC)

There is currently no material on the basics, e.g. the fact that all analog meters are milli- or microammeters at root, and are converted to voltmeters via a series resistance or to higher-current ammeters via a parallel shunt...but you think it is important to detail how RMS voltage is determined from a complex waveform? Jeh (talk) 05:48, 31 December 2011 (UTC)

Definition of VOM

A publication my students use states the VOM is Volt-Ohm-Milliammeter. I think my Simpson operator's manual makes the same statement.

I don't agree, the original meters only measured volts and resistance so VOM would have stood for "Volts Ohms Meter". Current measurement came later — Preceding unsigned comment added by DesmondW (talk • contribs) 22:26, 30 December 2011 (UTC)

Incorrect. The article states that the early 1920s pocket "watch style" multimeters measured milliamps and volts. And the "Avometer", also in early 1920s, was so named because it measured amps, volts, and ohms. The term "VOM" did not appear until after that. So I think it unlikely that the first instruments called "VOMs" did not measure current. Can provide an example of something that was a) called a VOM and b) did not measure current? Jeh (talk) 06:11, 31 December 2011 (UTC)

Request for Knowledge

I wonder if someone could be kind enough to add to this article whether the final two syllables of "multimeter" are pronounced like "millimeter" or "odometer", because I don't want to give those geeks at Radio Shack the satisfaction of knowing how clueless I am. :) Thanks in advance and feel free to delete this comment. MatthewDaly 18:49, 21 July 2006 (UTC)

More like "meter" than "met her". I can't fix the article as I don't know IPA. -- Mikeblas 01:00, 22 July 2006 (UTC)

like millimetre Tabby (talk) 07:39, 6 May 2010 (UTC)

The article needs to be wikified

There are no sections other than external links, I think there should be more. --Adam1213 Talk + 02:13, 22 July 2006 (UTC)

Feel free to edit it! -- Mikeblas 02:22, 22 July 2006 (UTC)

I was not all that certain on how to divide it up, otherwise I would of.

Feel free to do it for me--Adam1213 Talk + 13:25, 23 July 2006 (UTC)

You don't know how to edit it, or you don't know where the sections should be? -- Mikeblas 15:46, 23 July 2006 (UTC)

digits

The article says "For a modern DMM, such as a PC-based multimeter, the term "digits" actual maps to the noise performance of the device," and I can't make much sense of that. Can anyone expand on it or clarify it? -- Mikeblas 19:49, 13 September 2006 (UTC)

• I think the article is wrong. Digits is more of a measure of resolution (either decimal digits or DAC bits), not noise. "Effective bits" is more of a noise/AC measurement thing. -- Morcheeba 03:24, 4 January 2007 (UTC)
  • OK. I've deleted that; I was going to just tag it {{fact}}, but since it's been so long for that editor to explain himself, it might as well go right now. -- Mikeblas 15:19, 28 January 2007 (UTC)

Test Set

The reference provided is to a dedicated test set, not a multimeter with test-set features. The bullet here in this article says that multimeters with test set features are available, and I'm hoping to either find a reference to such a unit; otherwise, we'll remove the bullet as uncited. -- Mikeblas 17:26, 28 January 2007 (UTC)

With no reference added, I've remvoed the bullet. -- Mikeblas 17:59, 11 February 2007 (UTC)

Disambiguation

Just to mention, DMM (which redirects to the main article) can also stand for Digital Molecular Matter (a kind of simulation technique that basically uses physics to calculate the simulation... mass, velocity, momentum, inertia, etc. ). I recommend that a Disambiguation page be made.(I don't know how to make one...)

220.246.177.36 14:32, 22 July 2007 (UTC)Wiki_Flight_Simmer

Fuse protection

"Almost every multimeter includes a fuse, which will generally prevent damage to the multimeter if it is overloaded."

thats very incorrect. A fuse on an analogue meter only protects the highest current range, or sometimes 2. There is normally no effective fusing for other ranges, and analogue meter mechanisms are vulnerable to overcurrent on these ranges.

Back to back diodes are used to give at least partial protection.

And fwiw lots of analogue meters had no fuse at all. Tabby (talk) 20:03, 1 March 2008 (UTC)

Thanks for pointing this out, I fixed it up now --Adam1213 Talk 03:38, 24 April 2008 (UTC)

Almost every multimeter I've used had a fuse or circuit breaker; the ones that didn't were extremely low cost and quality to match. Also, you could blow the fuse by attempting to measure voltage while set to a resistance scale. Nibios (talk) 07:13, 21 June 2008 (UTC)

Budget meters with no fuse are very common/popular Tabby (talk) 07:41, 6 May 2010 (UTC)

Counts

A dual-slope A/D converter, as used in zillions of multimeters, essentially measures time or counts clock pulses, and so does not have the powers-of-two granularity this article formerly implied. I've removed the part about "conversion" counts not being the same as "display" counts. The merits of extra digits in the display are already described somewhat more dryly in the text. --Wtshymanski (talk) 18:54, 9 October 2008 (UTC)

Another peer review

Suggestions in the second peer review remain unused. Sillyfolkboy (talk) 20:06, 13 December 2008 (UTC)

The actionable ones have been applied. -- Mikeblas (talk) 22:53, 15 November 2009 (UTC)

Galvanometer confusion

An author seems to think a galvanometer and a moving coil meter are the same thing, but they're not, nor do they work the same. They key difference is that galvos have no return spring, and thus detect current but are incapable of measuring it. There are also other history steps missing. I'll rewrite this confusion at some point if no-one beats me to it. Tabby (talk) 07:44, 6 May 2010 (UTC)

Done Tabby (talk) 10:22, 6 May 2010 (UTC)

"This detected current, but due to absence of a return spring could not measure it." was removed, but its the key point about galvanometers imho Tabby (talk) 16:22, 7 May 2010 (UTC)

But galvanometers (nearly) always had some form of restoring force. Not necessarily a hair spring, but even Oerstead's compass had the Earth's magnetic field to restore the pointer to the zero-current position. The only galvanometer that had no restoring force would be a "ballistic" type, used to measure total charge not current. Could you show us a reference that says galvanometers typically didn't have restoring force? ( There's an IEEE magazine publication that explains this...I don't have the .PDF handy but it would be a good ref here and at galvanometer.) --Wtshymanski (talk) 16:34, 7 May 2010 (UTC)

I'm not saying galvos had no restoring force - they did, else the mirror/pointer would never return. But the restoring force was unpredictable, inconsistent, and not proportional to angle like a spring. That's why they were used in a wheatstone bridge arrangement, as detectors rather than measurers. Tabby (talk) 03:31, 9 May 2010 (UTC)

Maybe I'm wrong, I'd not heard of the d'arsonval/weston moving coil meter referred to before as a galvanometer. Tabby (talk) 03:41, 9 May 2010 (UTC)

A tangent galvanometer had a restoring force that was entirely predictable and consistent, although not linear with deflection beyond a small amount. --Wtshymanski (talk) 13:54, 9 May 2010 (UTC)

OK, I accept you folks are right about some galvos reading proportionally. The change from cotton suspension to sprung is a big step in the history, and I think could do with inclusion, even though I got my terminology wrong. Tabby (talk) 09:18, 18 May 2010 (UTC)

Agree, all of that would be good in the history section of Galvanometer, but multimeters started off (as far as I can tell) with the d'Arsonval movement and Weston's commercial version. Imagine running a power plant without meters..that's the fix that the industry was in before Weston. And I'm sure there are some European meter manufacturers waiting to be heard from, though Web-accessible resources haven't shown me much so far. --Wtshymanski (talk) 13:36, 18 May 2010 (UTC)

Image problem

This image isnt displaying, but I cant see why... http://en.wikipedia.org/wiki/File:1920s_multimeter_3738-4.JPG Tabby (talk) 10:21, 6 May 2010 (UTC)

Thanks :) Tabby (talk) 09:19, 18 May 2010 (UTC)

Battery check

Article currently says... "Battery Check" for simple 1.5 and 9V batteries. This reading can be made just as accurately with the ordinary low-scale DCV function. It is included in some meters merely as a convenience for the homeowner and "Do It Yourself" users

I thought the batt check scales current loaded the battery for better results. Might well be wrong though. Tabby (talk) 10:34, 6 May 2010 (UTC)

I checked the circuit diagram of an analogue pocket meter, and the 9v battery check scale is 10mA FSD. Its not just a current scale, it has both current shunt and series voltage resistor. 09:54, 7 June 2010 (UTC)

(edited own contribs for clarity) Tabby (talk) 14:11, 2 March 2011 (UTC)

Any analog multiple-scale current meter involves a very low-current microammeter and a current shunt to bring the scale to a reasonable range. The question is, is that shunt you found sufficient to realistically load the battery? In any case there are most certainly multimeters with battery check ranges that don't present a load; your result is valid only for your particular meter. The article's claim looks to me to be WP:OR also. I think we're better off without mentioning the issue at all. Jeh (talk) 06:20, 31 December 2011 (UTC)

Reorganization needed

This article is **terrible** and needs a complete re-edit. Many repetitions and no clear flow, I tried adding a clarification section but this was removed.DesmondW (talk) —Preceding undated comment added 22:20, 30 December 2011 (UTC).

You are correct in that there is a lot of repetition and poor organization in general. However the "clarification" section you added, as far as I can see, added more repetition. Not really an improvement IMO. Jeh (talk) 06:14, 31 December 2011 (UTC)

Accuracy section sucks

It fails to explain the x%+y type of accuracy, aka two-term accuracy description commonly used today by many brands of DMMs. This book explains it properly. JMP EAX (talk) 12:53, 6 October 2014 (UTC)

Better sources for existence of commercial products?

@Mikeblas: added a couple of "better source needed" templates regarding specific product categories, like automotive meters.

For a claim of "a product exists that does x," exactly what sources should we be looking for other than filthy commerce "commercial" ones? I don't see anything in WP:RS that says "commercial" sources are not preferred.

Now, granted there are books. In the pro audio/video field I own a couple of massive tomes that describe practices for studio and live sound and so on, and they do mention specific products. I suppose that could be considered a "better source." For multimeters there are some books like The Art of Electronics that are considered very reliable sources and describe a few of the products in this space. But books like that don't get updated very often. Jeh (talk) 19:00, 20 January 2015 (UTC)

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Burden voltage

Too many things are self evident for the relative people but are hard to comprehend for the rest!

I would like to point out that, as far as Burden voltage is concerned, once an ammeter (meaning essentially galvanometer configured to count current in Amps) is connected in series with a circuit (the usual way to measure current), the degree or percentage of Burden voltage in relation to the circuit voltage essentially depends from the relation of the instrument's internal resistance to the overall resistance of the circuit in question. It becomes a problem only if the coil's internal resistance (without "help" from shunts, which you shouldn't need if the current is not too big)) is not small enough compared to the overall circuit resistance, irrespective of the actual voltage of the circuit.

In other words, for every circuit voltage, the relative importance of Burden voltage depends on the ratio of the ammeter's total resistance towards the overall circuit's resistance, whether you use shunt resistances or not. I think you probably say the same thing, because "using a higher current range" essentially means using lower shunt resistance, which means to lower the overall resistance of the ammeter in relation to the circuit's overall resistance (assuming we are talking about DC of course).

So, could you make a comment about that? I think some clarification would be useful. Thanks! 2A02:587:451A:F100:BE:7F44:8221:A3A1 (talk) 00:54, 30 June 2017 (UTC)