Author Topic: EEVblog #1067 - Analog vs Digital Multimeters  (Read 19247 times)

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Offline Zbig

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Re: EEVblog #1067 - Analog vs Digital Multimeters
« Reply #25 on: March 26, 2018, 03:37:29 pm »
I still use my ancient Micronta FET input analog meter fairly regularly.  Sometimes seeing how a value is moving is more important than measuring it to 3 D.P.s.

Have you actually watched the video? The part where Dave shows that most bargraphs in digital multimeters (well, at least those shown in the video) are both faster (no mechanical inertia) and more accurate in displaying value changes and fluctuations?
 

Offline glarsson

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Re: EEVblog #1067 - Analog vs Digital Multimeters
« Reply #26 on: March 26, 2018, 03:48:45 pm »
You need a VTVM.
No. I have no use for any analog meter.
Analog meters are at an disadvantage in all use cases.
 

Offline ahbushnell

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Re: EEVblog #1067 - Analog vs Digital Multimeters
« Reply #27 on: March 26, 2018, 03:55:57 pm »
You need a VTVM.
No. I have no use for any analog meter.
Analog meters are at an disadvantage in all use cases.
Thats a joke son.  Vacuum Tube Volt Meter

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Offline schmitt trigger

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Re: EEVblog #1067 - Analog vs Digital Multimeters
« Reply #28 on: March 26, 2018, 04:00:27 pm »
A previous poster made an analogy (no pun intended) to an analog watch.

Analog watches allows to develop intuitive visual method to determine relative time for certain events. For instance, if the hour hand is almost vertical, and the minute hand is to the right of it, it means that I'm already late for my lunch hour.

It is similar with analog meters. Like nulling a circuit.

But other than that, DMMs win.
 

Offline jolshefsky

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Re: EEVblog #1067 - Analog vs Digital Multimeters
« Reply #29 on: March 26, 2018, 04:09:34 pm »
I sometimes think the biggest advantage analogue has today is to remove meaningless significant figures from measurements. So many seem to obsess over the 3 and above significant figures which almost no-one needs 99% of the time.

This is basically what I wanted to say as an "advantage" of analog. I think they are good as a learning tool because, given a circuit with typically 1%-5% tolerance components, they give you a tangible understanding of what 1% "looks like". Also, given the fairly low voltage-range resistance, making a habit of thinking about that resistance makes you a better engineer. Sure, 10M? won't affect many circuits, but when it does, you'll at least have a chance of remembering.

That said, I don't use analog really at all. At work, I use a Fluke 27V for pretty high accuracy to track long-term drift in the field, but it tricks me into trying to get +5.000V out of the adjustable voltage regulators when ±0.2V is acceptable, and ±0.02V is plenty accurate enough for adjustment.

I think if digital meters were "classy", I'd be more inclined to let the analog meters go, but an old Simpson is a work of art whereas even a Fluke looks like a chunky kids toy. For instance, if the LCD were rendered in a crisp, readable typeface rather than a pretty-good built-for-cost LCD 7-segment, I'd take notice.
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Offline Bud

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Re: EEVblog #1067 - Analog vs Digital Multimeters
« Reply #30 on: March 26, 2018, 04:28:20 pm »
That is true, Fluke 87-V display sucks donkey balls big time.

Analog displays have charm and charisma that digital displays lack.

As to use cases for representing information in analog form, next time you get in your car look at the speedometer.
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Offline xani

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Re: EEVblog #1067 - Analog vs Digital Multimeters
« Reply #31 on: March 26, 2018, 04:32:45 pm »
That thread got me thinking, why most digital meters are meters are soo poor on display front ?

It is basically "a number" for cheap ones, then "number + bargraph" for anything more expensive and only real change is when we get to top of the line >$300 multimeters.

Graphical displays are cheap, MCUs are basically free (and a ton of performance per mA), why we don't have affordable multimeter that have say a histogram of last few seconds as an option for display, or simultaneous display of various other parameters of signal ?

Instead of "look, the bargraph is wobbling" the display should just show "12.103v +/- 100mV with base frequency of 100Hz", maybe even replace a bargraph at bottom with a box plot

 
 

Offline Cnoob

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Re: EEVblog #1067 - Analog vs Digital Multimeters
« Reply #32 on: March 26, 2018, 04:51:46 pm »
Some of you need to get a room.   Please.
Function over form any day of the week.
 

Offline MisterDiodes

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Re: EEVblog #1067 - Analog vs Digital Multimeters
« Reply #33 on: March 26, 2018, 05:03:10 pm »
There is something Dave never mentioned (Or I didn't see it):  Sometimes DMM's will really get fooled by an AC waveform at higher crest factors - and that's why we still use the very good Simpson 260's for checking various AC motor drive systems, used right along with DMM's.   In use every day, because the analog meter movement itself can do a better job of RMS conversion on some distorted waveforms - at least for what we need.  For instance - the Crest Factor limit is typically only 3~6 for a Fluke 87 and only 1.5 at the extreme ends of the AC scales.  We use Simpsons when the crest factor is getting upwards past 6, at least for some tests.  At this point the high crest factor renders the "TrueRMS" DMM useless.

I would point out that there is no such thing as a perfect meter for -every- application, so use the right tool for the job.

The graphic nature of the analog gauge registers information so much faster on a human brain, and that's why most aerospace cockpits are designed with a dual analog / digital type display readout.

Some of our custom designed test equipment is built the same way: with a high end low-noise input amp and MCU control/ logging system, but the operator readouts use an analog meter display.  It's much faster and foolproof for the operators to glance at the gauge and know if a certain test is within spec or not - and a real analog mechanical gauge is still used if we're in an environment where we can't have the relatively huge EMI of any "graphic display" panel near the sensitive test area.

Here's another example of an "Analog" meter display built with a more modern hardware front end.  In the case of a null detector a digital display would be a big disadvantage.  You need to watch the needle to finesse the center zero position when you are getting a measuring bridge in balance - at virtually true zero current flow (at least down to a few 10's of fA):

https://www.tegam.com/shop/resistance/avm-2000/avm-2000-null-detectornanovoltmeter/




« Last Edit: March 26, 2018, 05:05:48 pm by MisterDiodes »
 
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Offline PA4TIM

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Re: EEVblog #1067 - Analog vs Digital Multimeters
« Reply #34 on: March 26, 2018, 06:08:01 pm »
The AVO analogue meter I have is accurate to 1% fs DC ...
But with 10kohm/V (or close to it) it distorts the circuit more than that, especially with todays low power designs, probably causing some malfunction.  :-BROKE
Sometimes that is an advantage especially on power circuits, It also has a 10 and 40 meg ohm range not mant digital meters have that it is also water and vapour proof never seen a digital one of those.
Most of my DMMs can measure over 40M, and some can measure conductance (1/ohm in siemens) There are many DMMs that are waterproof. Dave has a video where he goes swimming with a Fluke.

Hij have a nice collection analog meters (15 of my nicest and oldest are on display in the livingroom)
I use them sometimes for fun but you must be real masochistic to still use them. About seeing fast the value like on an analog watch....yeah sure, with enough light, a magnifier and a sliderule to calculate how much volt one division is. And then the meters that let you gamble the scale is 10M fulkl scale or you need to multiply the reading by 10M. I have a meter that has a 25 range but no 25 scale.
Example, with your face straight in front of the meter due to parallax error and the probes almost out of reach because of that you see the needle at the 3rd division between 2 and 4 in the 10V scale. There are 5 divisions so 0.4V per division. So you measure 2 +1.2 = 3.2V. Yes, very quick and easy in use such a meter.

The only thing I prefer an analog meter for, is as null detector. I have several and some do 1 uV full scale.

Adjusting things for peakvalue only if you have cheap slow DMMs. My digital benchmeters are much faster than any analog meter and with much more resolution and without loading the circuit. Most have a >1Gohm input impedance. (my favorite 10G including the 10V range.) They are all TRMS some of the have a 1 MHz bandwith. Compare that to the few hundered Hz the average analog meter does (and not even close to RMS if the signal is not a perfect sinewave.)

So, I realy love analog meters like I like my 1936 Austin 10 (on a nice summerday on a quiet road, not for every day use)

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Offline BravoV

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Re: EEVblog #1067 - Analog vs Digital Multimeters
« Reply #35 on: March 26, 2018, 06:17:18 pm »
Popular good DMM say like Fluke 87V currently at Amazon is at $387 compared to ...
... Simpson 260 in 1946, with today money ...  ::)



Wonder what hobbyist bought back in those days ?  :-//

Offline Cnoob

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Re: EEVblog #1067 - Analog vs Digital Multimeters
« Reply #36 on: March 26, 2018, 06:19:46 pm »
My Hioki  DT4282 has a slow measurement feature.
|It's normal measurement  update rate is 5 per second.
I have 3 other DVM's they all bring different functionality to the bench
 
 

Offline xani

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Re: EEVblog #1067 - Analog vs Digital Multimeters
« Reply #37 on: March 26, 2018, 07:27:57 pm »
Popular good DMM say like Fluke 87V currently at Amazon is at $387 compared to ...
... Simpson 260 in 1946, with today money ...  ::)



Wonder what hobbyist bought back in those days ?  :-//
Apparently it is still produced (well, a revision) and on sale for only $279.95 https://www.amazon.com/gp/offer-listing/B002R6MWL0/ref=dp_olp_new_mbc?ie=UTF8&condition=new
 

Offline glarsson

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Re: EEVblog #1067 - Analog vs Digital Multimeters
« Reply #38 on: March 26, 2018, 07:33:21 pm »
Analog watches allows to develop intuitive visual method to determine relative time for certain events. For instance, if the hour hand is almost vertical, and the minute hand is to the right of it, it means that I'm already late for my lunch hour.
It's not intuitive at all if you don't use it. I transitioned away from quaint angled sticks in the second half of the seventies, both for time and multimeter purposes.
 

Offline Kleinstein

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Re: EEVblog #1067 - Analog vs Digital Multimeters
« Reply #39 on: March 26, 2018, 08:31:06 pm »
I still sometimes use an analog one - it's good enough in many cases and batteries last very long. No need to turn on the meter, just turn on the brain.

The early and and many cheap meters have quite a high burden voltage on DC-amps (usually 200 mV + fuse) - many of the analog meters were better in this respect. On the analog meter I have it's 60 mV. However some of the advantage can come from not having the fuse.

However already with AC amps it's usually a problem with the analog meters - though I once have used a rather fancy one with a current transformer for the AC current ranges. AFAIR it had a 60 amps or so AC amps range.
 

Offline vk6zgo

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Re: EEVblog #1067 - Analog vs Digital Multimeters
« Reply #40 on: March 27, 2018, 12:20:20 am »
Quote from: oldway link=topic=106744.msg1462199#msg1462199e  date=1522059297
Analog multimeters are not safe at all, never use them on high energy circuits..... :scared:

What do you imagine we used before DMMs? :palm:

The AVO 8 & the like were very well engineered, with large clearances, heavy insulation, & thick Bakelite cases.
Because they were large, meters of this class were not used handheld.
Instead, they were placed on the floor, rested on a "Tech's stool", or hung up by the handle.

In any case, the operator could be a metre or more away from the meter & still read it clearly, which reduced the possibility of injury in the very unlikely event of the meter case being breached.

In more than 40 years working at high power Radio & TV transmitter sites, I only saw one AVO 8 which had been "blown up".
The Bakelite case was not breached, the movement was clearly charred, the dial glass was cracked, but not
shattered.

DMMs are mostly used handheld, & have lightweight cases, so your chances of escaping injury are that much less.
 
PS:- sorry about the ( sort of) double post----I was sure the iPad had lost the first one, so I rewrote it.
This is a better version, hence it's renewal.
« Last Edit: March 27, 2018, 11:35:42 am by vk6zgo »
 

Online floobydust

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Re: EEVblog #1067 - Analog vs Digital Multimeters
« Reply #41 on: March 27, 2018, 12:48:12 am »
I've been screwed once by DMM's.

Repairing a CNC machine, I read good mains voltage both sides of a fuse terminal block- where an analog multimeter read zilch on the load-side.  Fuse tested good.
It was leakage currents from coolant mist that gave me a good reading on the DMM. In the end it was the fuseholder (not fuse) that failed, the spring fatigued and open circuited.

Some DMM's have low Z volts, to prevent ghost voltages like Fluke 114,116, 117 for very good reason. Also good working on cars, there's usually water under the hood on connectors etc.

An analog meter or LowZ is only thing I use troubleshooting outdoors.
But everybody here waaaa about about accuracy, it's not always what you need.
« Last Edit: March 27, 2018, 12:51:47 am by floobydust »
 

Offline Andrey_irk

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Re: EEVblog #1067 - Analog vs Digital Multimeters
« Reply #42 on: March 27, 2018, 02:06:51 am »
If you were to measure say 20 different values in a row what meter would you prefer? I bet you wouldn't fancy multiplicating and dividing every time in order to get a result.
If you had a good DMM you'd be able to workaround its "quirks" in most of the cases (need a low input resistance? add a resistor for god's sake), but if you had only an analog meter you wouldn't.
Finally, if I suspect something else present on the rail apart from DC I will use a scope rather than poke around with the needle's movements.
Analog meters are obsolete. Period.
 

Online Brumby

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Re: EEVblog #1067 - Analog vs Digital Multimeters
« Reply #43 on: March 27, 2018, 02:23:56 am »
Analog meters are obsolete. Period.
So is my old 486 computer running Windows 3.11 - but I still can't type faster than it can handle.

And without a battery, you can still use an analogue meter for everything except resistance measurements.  A DMM without a battery makes a poor wheel chock.


There's also this:
- Very short touch to see if there are big amps without blowing a fuse
If you suspect there is a potential for a very heavy current flow, you can make a glancing touch with the probes of an analogue meter - and the initial needle velocity will give you a qualitative indication.  If you know the current might be under 1A or over 15A and you are on a 10A scale, one quick touch will tell you which way it is going.
« Last Edit: March 27, 2018, 02:33:00 am by Brumby »
 
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Offline oldway

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Re: EEVblog #1067 - Analog vs Digital Multimeters
« Reply #44 on: March 27, 2018, 06:23:19 am »
Quote from: oldway link=topic=106744.msg1462199#msg1462199e  date=1522059297
Analog multimeters are not safe at all, never use them on high energy circuits..... :scared:

What do you imagine we used before DMMs? :palm:

The AVO 8 & the like were very well engineered, with large clearances, heavy insulation, & thick Bakelite cases.
Because they were large, meters of this class were not used handheld.
Instead, they were placed on the floor, rested on a "Tech's stool", or hung up by the handle.

In any case, the operator could be a metre or more away from the meter & still read it clearly, which reduced the possibility of injury in the very unlikely event of the meter case being breached.

In more than 40 years working at high power Radio & TV transmitter sites, I only saw one AVO 8 which had been "blown up".
The Bakelite case was not breached, the movement was clearly charred, the dial glass was cracked, but not
shattered.

DMMs are mostly used handheld, & have lightweight cases, so your chances of escaping injury are that much less.
I think you do not know at all the subtleties, or especially the weaknesses of the Avo 8  .....

First of all, I learned to drive with my father's Simca Aronde: this car had no seatbelts, no airbags, no ABS and was not crash tested ... and yet, everyone was driving with such insecure cars.

Safety standards have changed and it would be forbidden to drive today with such a car.

With regard to electrical safety, it's the same thing.

So to argue that we used in the past analog multimeters on high energy circuits, it's simplisly stupid.

You can't ignore actual safety rules.....

The avo 8 is very dangerous because it is the same terminals that are used for both the voltmeter and ammeter function .... an error can easily be made.

In addition, the so-called cutout protection does not protect anything because:

1) the breaking capacity of this cutout is very low
2) the protection is activated by the needle arriving at the end of scale stop ..... but if you are in range DC amps and you measure AC current, the needle does not move at all and does not cause the opening of the cut out.

Then, the principle that there is no danger because we do not hold the meter in hands is totally wrong and shows that you do not know anything about electrical safety.

On a high energy circuit, the risk comes from creating an arc that becomes explosive.

This arc is formed at the contacts, that is to say the test probes held by the operator and ionised air let the arc to close between phases with consequences of serious burns, damage to the eyes and a risk of electrocution.

With high energy circuits, every simple error have very serious consequences and it is not for nothing that the digital multimeters have special fuses with high breaking capacity in the current inputs.
 

Offline Cnoob

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Re: EEVblog #1067 - Analog vs Digital Multimeters
« Reply #45 on: March 27, 2018, 06:45:38 am »
The Simpson 260-8p cost £430.80 new. Safety features. Transistorised relay (actuates in milliseconds) for overload protection but not on all ranges.
10amp range unfused. There is a cheap 1amp 250v quick blow fuse fitted and a busman 2amp 600v high energy fuse fitted.
Needless to say the manual and data sheet have no cat ratings listed and people used these type of meters on industrial equipment. 
Anything goes wrong you haven't got a leg to stand on.

The standard is to record data, to 3 significant digits not decimal places. Analogue meters at best is 2 significant digits and if you are like me on your way, to 60 your eyes are too f**ked to read the scale with sufficient accuracy.

Most hand held  DVM have a battery life of at least 100hours (oled and graphic excluded). I suppose that is a real hardship that you have to a spare battery around with the spares for your other battery operated equipment.

My first meter I owned  was a Russian analogue meter, my second was a fluke 8020 (1982)  after using that fluke I even refused to use analogue meters.

Over the years since 1982 DVM have become better and more versatile, hence more useful. Analogue meters  have not really  changed.
As Dave said they a few niche uses but they are niches and not for use as a general purpose  everyday instrument.
The DVM is one of the best tools and it's good enough to be classed as a tool.   



 
 

Offline JPortici

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Re: EEVblog #1067 - Analog vs Digital Multimeters
« Reply #46 on: March 27, 2018, 07:34:58 am »
As to use cases for representing information in analog form, next time you get in your car look at the speedometer.

don't you love it when the speed and RPM gauges are in sync?

i found it to be extremely pleasing in the previous 500 abarth


the late 2016 restilyng with the new display (of questionable quality)? not so much.

I also found it extremely pleasing to look at the "morphing" gauges that change the background if the car is in eco/sport/electric/whatever mode (see new renault/audi/volvo/lexus) to display the same thing  in different contexts
« Last Edit: March 27, 2018, 07:38:40 am by JPortici »
 

Offline Fungus

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Re: EEVblog #1067 - Analog vs Digital Multimeters
« Reply #47 on: March 27, 2018, 07:45:03 am »
I sometimes think the biggest advantage analogue has today is to remove meaningless significant figures from measurements. So many seem to obsess over the 3 and above significant figures which almost no-one needs 99% of the time.

a) Sometimes you need those digits. Worrying about whether they're accurate seems natural to me, not an "obsession".

b) What's stopping you from buying a DMM with less digits? They exist.

    Maybe you could paint over the last digit on screen with Tipp-Ex (or equivalent) if your bother you.

 

Offline Fungus

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Re: EEVblog #1067 - Analog vs Digital Multimeters
« Reply #48 on: March 27, 2018, 07:58:06 am »
Analog meters are obsolete. Period.
So is my old 486 computer running Windows 3.11 - but I still can't type faster than it can handle.

Sure, but any professional writer would soon replace if it required multiple weird key combinations to get anything other than basic letters of the alphabet (eg. parenthesis or full stops...)

And without a battery, you can still use an analogue meter for everything except resistance measurements.  A DMM without a battery makes a poor wheel chock.

Luckily for us, DMMs have battery indicators to tell us in advance when that's likely to happen.

Plus: They're smaller and cheap enough that we can own more than one without taking up the entire bench. The chances of multiple batteries dying simultaneously is very slim.


There's also this:
- Very short touch to see if there are big amps without blowing a fuse
If you suspect there is a potential for a very heavy current flow, you can make a glancing touch with the probes of an analogue meter - and the initial needle velocity will give you a qualitative indication.  If you know the current might be under 1A or over 15A and you are on a 10A scale, one quick touch will tell you which way it is going.

You can bridge the fuse in your DMM. A quick touch of the probes will send the bar graph over to the right just like an analog meter!

« Last Edit: March 27, 2018, 08:10:50 am by Fungus »
 

Offline Cnoob

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Re: EEVblog #1067 - Analog vs Digital Multimeters
« Reply #49 on: March 27, 2018, 08:01:48 am »
Car speedos and aircraft instrumentation are designed so a pilot or driver can take a quick glance and roughly see if everything is ok or not. So they are not distracted form their main task.
In fact on older instrumentation we had to paint green, yellow and red bars around the dials so the pilots would know the instrument was showing safer operating area or not.

Multimeters  are measurement devices.
 


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