Analog multimeters, are they still useful?

[tooki]

I just thought of this because of a recent project:

While I don’t think (ordinary) analog VOMs have a lot of uses anymore, there’s definitely a place for analog panel meters: when you need a passive voltage or current display that works without its own power supply.

I recently used one in a project that has up to 40kV applied to some electrodes. In addition to the quick discharge circuit in the HV power supply, I added a redundant discharge circuit that integrates an analog panel meter. The 100uA discharge resistors are connected in series with a 100uA panel meter for which I made a custom scale. This provides an extra voltage display in addition to the digital display on the power supply.

[dzseki]

I inherited an MTM Vielfachmesser III (Made in GDR) analog multimeter about 15 years ago, now, as I am 37, still using it. My main driver is a bench DMM, granted, but when I want to measure something on the spot (then it is usually a less critical measurement anyway), I reach for my trusty old MTM 99% of time, while my kids are happy to test the continuity on my spare DMM in the meantime...

[MrAl]

Is there anyone who still uses analog multimeters?

Hi,

Despite the better precision of digital meters analog meters are still useful and have their advantages.

For one thing, they do NOT require batteries.  This can be an important feature.  If you want a digital meter that does not require batteries you have to get a bench meter that plugs into the wall, or get a battery adapter or something else that plugs into the wall.

Another use is when you want faster response.  Many analog meters can respond faster than digital meters, and some digital meters can take 3 to 5 seconds just to get one reading as the meter digits start to stabilize.
An example is if you want to test your car battery when you start the car to see how low the battery voltage drops when the engine first starts to turn over.  A cheap analog panel meter will jump right down to the lower voltage when the engine start to turn while a digital meter will just start to change and probably won't catch the lowest voltage as the engine starts running, but then it's too late.
It's true you can get an oscilloscope for this and that would work even better, but that's not a meter that's a different instrument.

Then there is the antique thing.  I have an old Westinghouse panel meter that measures current, the face is 10 inches in diameter.  God only knows when it was first made.  I don't actually use it anymore, but it's pretty cool.  You can see how they made things back then and compare to how they make things now.  I wonder if anything we have now like digital meters will last 100 years like this old meter would.  It's doubtful.
So, chalk up another advantage: longevity.
I also had an old Simpson multimeter, and an old Radio Shack meter which I was sorry I threw out because it had a special dual range feature and FET input stage, so it was high impedance even though an analog multimeter.

Many devices have their own niche not just analog meters.

[Kleinstein]

Not needing a battery is big plus. There is also no need for a turn on / off. So they can be handy to keep connected to check a current / voltage all the time.
No need for battery is also a plus for a 2nd / 3rd meter that is seldom used, but nice to have, so one has to run less or take the normal meter out of a circuit.
There are also fast reacting digital meters (though not so much portable ones) - the limit here is more how fast one can read the number(s).

[Zenith]

Despite the better precision of digital meters analog meters are still useful and have their advantages.

For one thing, they do NOT require batteries.  This can be an important feature.  If you want a digital meter that does not require batteries you have to get a bench meter that plugs into the wall, or get a battery adapter or something else that plugs into the wall.

It depends on the analog multimeter. One of mine is FET VOM, which has a 10M input resistance. It's the equivalent of a VTVM, and so good for low voltage high impedance circuits, but it needs a 9V battery. But mostly analog multimeters don't need a battery for voltage and current, which can be a definite advantage. Some of the cheaper digital DMMs gobble up batteries.

They are better for peaking adjustments. You can of course use an analog scope for that. A lot of vintage kit specified voltages measured with a 20kOhm/volt meter and you may get different results if you use anything else. Note that analog VOMs had various figures of merit, from 1kOhm/volt or less to 100kOhm/volt. 20kOhm/volt was typical for a quality VOM 50 years plus back. Some analog VOMs have a voltage range going well over 1kV, which can be useful.

With some things, such as panel meters, they are plenty good enough, and you don't want the extra complexity of arranging the supply for a digital panel meter.

As for analog meters lasting - well sort of. They are more delicate and don't like drops a digital meter would cope with easily. Precision resistors can drift with time, especially the ones produced decades back. Magnets weaken with years of aging.

I've got half a dozen analog multimeters. I don't use them much but I'm glad I've got them.

[ftg]

One thing a purely analog meter is good at is measuring DC rails in high power RF amplifiers with the case open.
Often there is enough RF ripple on the supply rails or just in the air to confuse digital meters, while the AVO 9 is still perfectly fine.

[Zero999]

Not needing batteries, to measure voltage and current,  is the main reason why I have an analogue meter in my toolbox just in case the battery in my digital multimeter goes flat.

[CaptDon]

One of the best uses for an analog meter is in radio alignment and frequency adjustment. 'Peaking' an I.F. strip and zero beating to frequencies when the detector can provide the D.C. quantity is so much easier with an analog meter movement. In the early days of DMM's some even included a small 'zero center' analog meter. Most only showed +/- 100% of selected full scale without any actual 'value' markings. I seem to recall even Simpson offered such a model that incorporated a so called 'edgewise' meter.

[martin1959]

Analog meters are nice for demonstration and education purpose.

Example: Demonstrate working principle of a voltage divider or potentiometer by connecting 2 analog voltmeters to the upper and lower half of the potentiometer. Move the potentilmeter slider and watch the two analog meters respond in opposite directions.

I did such demonstration in a little "magic show" for engineer colleagues. Instead of a potentiometer, I connected 2 PPTC (self-resetting fuses) in series, forming a voltage divider. With suitable power applied, one of the PPTCs would "win", i.e. get hotter (and increase resistance) sooner and take almost all the voltage while the other one would remain/get cooler (and decrease resistance). This voltage divider of 2 PPTCs then reaches a stable "state". However, with the help of a heat gun, you can force the "state" to change by heating up the "cool" PPTC resistor. It will then end up in the other stable "state".

Could be a candidate for the Guiness book of records: The slowest ever produced electronic 1-bit memory cell which needs 20 seconds or more to change state.

[BillyO]

Not needing batteries, "peaking" adjustments, quick test jigs, and following changing signals have all been mentioned but none of these will absolutely prevent the demise of the analog meter.  However, as long as there are zero EMI emission environments (physics, engineering, medical .. laboratories) there will be a high dollar demand for non-electronic analog meters like the Simpson 360/370.  These still sell for well over $500 for some models.  Even over $1000.

[CatalinaWOW]

The demise of analog meters will not be because of what they can or can't do.  It will be because the economies of scale tip so far against them that they just will fade away.  Not enough volume to pay a single person who knows how to mount a hairspring, or load pivot bearings or all the other little fiddly skills that go into these.  They are close to manufacturing extinction already, almost all of the market is NOS, or used material.

[Kleinstein]

There is still some market for simple analog meter movements. Once the plans are there they are not that difficult to produce. One still finds analog movements in simpler battery testers - so they seem to still reasonable cheap at the low end. It may not be good for a new practical multimeter, but could still be good as part of an instrument / power supply / charger.

For many uses there are still enough old analog meters around - if treated well they can last very long. I still have my first 40+ years old analog multimeter.

[Gyro]

I restored an AVO 9 Mk3 2 a couple of years ago, it took quite a while, repairing and adjusting the overload trip, leaf switch contacts etc. Since then, it's been a bit of a love hate relationship, it's bulky and heavy, but the display is much clearer at following  moving trends than my DMMs. After all the time and effort I lavished on it, I would feel very sad if I had to part with it now. The 3kV ranges and transformer based AC current ranges are nice too.

[MrAl]

The demise of analog meters will not be because of what they can or can't do.  It will be because the economies of scale tip so far against them that they just will fade away.  Not enough volume to pay a single person who knows how to mount a hairspring, or load pivot bearings or all the other little fiddly skills that go into these.  They are close to manufacturing extinction already, almost all of the market is NOS, or used material.

Like CRT scopes

[Zenith]

The demise of analog meters will not be because of what they can or can't do.  It will be because the economies of scale tip so far against them that they just will fade away.  Not enough volume to pay a single person who knows how to mount a hairspring, or load pivot bearings or all the other little fiddly skills that go into these.  They are close to manufacturing extinction already, almost all of the market is NOS, or used material.

Like CRT scopes

There's a lot more to making a CRT than making a moving coil meter. You can still buy moving coil meters made in China, and by a few makers in the West. If there was a serious need for either, the knowledge isn't lost and we get better at making things. If there was sudden need for buggy whips or collapsible opera hats, there are still people who make them, and we could gear up to make them in quantity.

[CatalinaWOW]

You can recreate old tech.  But as the market shrinks it isn't worth it.  As both of you point out there is still a small market and sources for analog meters.  Not dead but moribund.  Who knows it could have a resurrection like vinyl record or vacuum tubes.

[MrAl]

The demise of analog meters will not be because of what they can or can't do.  It will be because the economies of scale tip so far against them that they just will fade away.  Not enough volume to pay a single person who knows how to mount a hairspring, or load pivot bearings or all the other little fiddly skills that go into these.  They are close to manufacturing extinction already, almost all of the market is NOS, or used material.

Like CRT scopes

There's a lot more to making a CRT than making a moving coil meter. You can still buy moving coil meters made in China, and by a few makers in the West. If there was a serious need for either, the knowledge isn't lost and we get better at making things. If there was sudden need for buggy whips or collapsible opera hats, there are still people who make them, and we could gear up to make them in quantity.

I mentioned the CRT scopes because it seems not long ago there were CRT scopes available all over the place.  Then one day there were digital scopes with impressive features and then CRT scopes were less desirable even if still available.  CRT scopes are actually better for some things.

[Zenith]

A similar thing happened with CRT monitors and flat screen monitors, and with HDDs and SSDs. Both were around for ages as an expensive, not particularly good niche product, then suddenly prices dropped and performance improved drastically and there was a fairly rapid switch over.

There are still a few makers of CRT scopes, but it's not where the action is in the scope market.

https://www.twintex-china.com/Analog-Oscilloscopes.html

It would be interesting to know where they get the CRTs from. They might be using NOS or I suppose if you are prepared to order 10,000, someone in China maybe already making valves for the audio market, would do it for you. If you are making an analog scope there must be lots of specialised things you have to source, such as EHT multipliers, controls and switches and the mu-metal screen.

[Ground_Loop]

My analog meter is permanently stationed on my variac.

[jonovid]

yes

[MarkT]

Where you need to rapidly scan many displays to find which are abnormal, they are preferred. That's why such displays are still found in many aircraft.

But arguably bargraph displays are better than rotary dial displays in this context as they can be arrayed side by side neatly.  (some multimeters have a crude bargraph as well as digits).

I've found that an analog meter on a bench PSU is more convenient, both for seeing the nature of current fluctuations and for rapidly setting an output voltage - a 4 digit digital display rapidly changing conveys less information than a needle swinging.

[tggzzz]

Where you need to rapidly scan many displays to find which are abnormal, they are preferred. That's why such displays are still found in many aircraft.

But arguably bargraph displays are better than rotary dial displays in this context as they can be arrayed side by side neatly. 

Counter-example, where there are multiple groups of four dials, one for each engine.


Rotary analogue meters are a well-understood and reliable technology, which can be an overriding consideration.

And, of course, good luck trying to replace one of these with a digital readout.

I've found that an analog meter on a bench PSU is more convenient, both for seeing the nature of current fluctuations and for rapidly setting an output voltage - a 4 digit digital display rapidly changing conveys less information than a needle swinging.

Yup, particularly the rate of swing.

Also works with using a ballistic galvo to measure charge.

[tooki]

The demise of analog meters will not be because of what they can or can't do.  It will be because the economies of scale tip so far against them that they just will fade away.  Not enough volume to pay a single person who knows how to mount a hairspring, or load pivot bearings or all the other little fiddly skills that go into these.  They are close to manufacturing extinction already, almost all of the market is NOS, or used material.

Analog multimeters have certainly largely disappeared. Analog panel meters, on the other hand, are still somewhat common. Certainly not as common as they once were, but still something you see on new installations all the time. So I don’t think they’re going away any time soon.

[tooki]

There's a lot more to making a CRT than making a moving coil meter. You can still buy moving coil meters made in China, and by a few makers in the West. If there was a serious need for either, the knowledge isn't lost and we get better at making things. If there was sudden need for buggy whips or collapsible opera hats, there are still people who make them, and we could gear up to make them in quantity.

I suspect that the knowledge needed to make top-quality color CRTs is already lost. As I understand it, there was tons of institutional knowledge involved in making the very best ones (like Trinitron) and those people retired 20 years ago. I think if we wanted to start making those again, it’d take us many years to redevelop the process.

It’s kinda shocking how quickly manufacturing knowledge can be lost. Look at how difficult it has been to recreate Polaroid film, even with lots of highly experienced Polaroid employees. It also shocks me at how quickly documentation gets thrown out when companies are closed, sold, or even just move. We blink, and the information on how to make something unique is simply gone.

[BILLPOD]

My analog meter is permanently stationed on my variac.
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