Should I get an analog VOM?

[FenderBender]

Hey guys,

I've been thinking. We have a lot of analog meters at my school. (It's just a high school.) But it's interesting how its easy to see changes in what you are measuring.. But as for actually being practical, does analog still have a home today for measurement? Scopes sure but how about VOMs.

I was snooping around the store room and we actually have a few Simpson meters. Must have cost big bucks back in the day. Never used them, but they have always intrigued me.

Again, most will tell me that "this depends on the type of work you do". But in general..

Thanks.

[nanofrog]

Generally speaking, I'd say a DMM is more useful (more accurate, can have additional features, and easier to use IMHO). For example, if you connect the the probes in reverse on a voltage using a DMM, it just adds a Minus sign in front of the value, while an analog meter will swing the needle far left (0 or infinity).

Where a VOM has the advantage though, is if you need to watch trends of slowly changing voltages or currents. A scope can do this as well, so it's far more useful IMHO.

Rather simple, but I hope this helps.

[EEVblog]

In general, no, the analog VOM has essentially no value any more. They are all but a novelty.

Although requiring no batteries for voltage and current measurement is kinda nice!

Dave.

[Lightages]

Hmmm.... I am trying to think about the last time I thought to myself that I had better get out my analog meter. I cannot think of any case where I would have benefited from an analog meter for a measurement. If it was that important to see a trend of some form that I could not follow it with a digital meter then I would get my handheld scope or bench scope out to watch.

I would say don't bother with an analog meter, really not that useful.

[Dawn]

"this depends on the type of work you do"

I'd have to agree on that. I work in RF. There's just some jobs you run into that a DMM isn't suitable. Even though most everything I do I use a Fluke 87 or my bench Ballantine 3028 DMM, sometimes I have to pull out an analog VOM or my bench HP 410C and 400EL. Some of us have to work daily with older equipment. In many cases, typical operating voltages annotated on schematics are given in 20k ohms/V. Equipment that originally used proprietary test sets may be as low as 1K ohms/volt and procedures are written often for their use with often include 20k measurements if a test set is unavailable. We're talking about equipment made well into the 90's still used the Simpson 260 & Triplett 60/630NA as reference test equipment all still being made today. Bar graphs in DMM's even with expand features can fail to indicate very small trends like a minor dip in an alignment procedure. In multiplier stages, monitoring the emitter voltage of the preceding state to pre-adjust the current stage, the dip can be so tiny, it can be just a nudge indicating that the next stage is going into resonance. AC measurements where noise is a component can drive you crazy on a DMM or scope where the damping factor of a mechanical movement makes it easier for the eye to make an average measurement. Current measurements for many of the reasons above are also best done analog in the case where the trend is more important then the static value.

[Bored@Work]

If you get a reasonable good one, reasonably cheap, and if you already have a few good digital meters, then you could consider adding one to your collection. The problem is that most analog, reasonable cheap meters build these days are crap. Most is low-end stuff that is easily beaten by even the cheapest digital meter.

One of the power supplies I occasionally use has a digital voltmeter and an analog ammeter. I turn to it when I know the circuit I want to power has rapid current consumption changes all the time as part of its normal operation. The analog ammeter isn't so distracting in these cases, compared to the constant flickering of a digital ammeter.

I also occasionally use an analog meter when I have to watch really slow voltage changes. This is more for nostalgic reasons than out of a real need. It is just more fun seeing the needle moving slowly to where it should be than looking at a digital display.

[SeanB]

Analogue VOM is perfect if you need to leave it in circuit for a few days, no battery to go flat, and no powering down. As well often they have a lower burden voltage on the current ranges than most DVM's, so are more useful in low voltage current measurement. Often the FS voltage is under 200mV.

[pullin-gs]

There is no reason to get one.
I have one though and use it from time to time.
99.9% of the meter-work I do can be handled by a nice Simpson.

[digsys]

I use one for tracking LF power fields in the ground, and any inteference, using a custom loop antennae.
I see by how the needle vibrates and the extent, whats going on underground. And as I do a walk around, I get a feel
of the coverage. The other place I like them is on a large power display panel. I can glance over and see an instant
visual pattern of all the meters, don't care about the values. Many power distribution boards still have them for that reason.
You colour the last 1/4 say of the display in red, first eg 1/2 in yellow, centre green, and you don't need any training in
what it means. Can't colour a digital readout :-)
And 99.9% of the time I use digital without doubt. But they are STILL very handy in some circumstances !

[steve30]

For my own personal hobby stuff, I love my analogue AVO meters. They are very useful and are very good quality pieces of kit, regardless of whether it is a more modern one, or a very old one.

But the only digital meters I have are the super cheap £5 type, and a very old good quality one which needs some repair/calibration. Hence, the AVO is my 'every day' multimeter.

If you can get a good quality working analogue meter with a good spec for a reasonable price, then you can probably find a use for it. As you mention they are good for noticing changes. But if you can't get one for a good price, or require the high input impedance or very fine resolution of a digital one, then its probably not worth bothering.

[FenderBender]

Thanks everyone. I've taken all of your suggestions to heart. I figure if I'm going to buy an analog meter, I don't think I will buy a $300 Simpson but something cheap...though I don't know who even makes a good analog meter these days.

[JohnS_AZ]

I have several handheld DMMs and a couple bench meters that I use for probably 99% of the measurements I make. For that other 1% my old Simpson analog multi-meter is invaluable.

Usually I'm looking at a slowly varying sensor signal, and you just can't visualize what's happening on an digital display.

I'd be looking at hamfests and swap-meets for a good old one. New good units are WAY too expensive, and new cheap ones are pretty much crap.

[Jon Chandler]

In audio work, pink or white noise is often used for level calibration.  In my experience an analog meter is much easier to use to see the average level of the random noise.

[Lightages]

If you do buy an analog meter, then there are things to watch out for. There is a specification for the number of ohms per volt. This number should be over 20K ohm per volt to be a useful. Meters with mirrors behind the needle are easier to make readings without parallax error.

If you actually buy a used meter there can be some problems from misuse. Look for bent needles, sticky movement, and cracks in the case. You can check for sticky movement by rotating the meter back and forth and watch the needle moves freely. Bent needles are a result of people using the wrong range and the needle flying over against the stops.If the case has any cracks, it has probably been dropped and the movement is probably damaged. Also check to make sure you can zero the needle correctly and also set the zero point on the ohms range.

[saturation]

If you are given a quality analog meter for free, you can use it and compare the various techniques mentioned by the folks who prefer it against a DMM that has a fast bar graph.  But I would not buy an analog meter.  At the least, the impedance is too low for most circuits today that it will load most anything you probe, except for items like power output stages or AC line powered devices.

[Bored@Work]

I don't think I will buy a $300 Simpson but something cheap...though I don't know who even makes a good analog meter these days.

A sanwa YX-360 series meter would be an affordable meter. But, they have been so widely copied that it is hard to get an original one. If you see on for 10 or 15 Euro you can be sure to see a fake. But if you see one for 70 or 80 Euro you can't be sure it is genuine. Bulk purchase price for fakes is around USD 4 / piece, 1000 MOQ, so the ebay sellers still make money from their 15 Euro offerings.

Some of the fakes are obvious, using a "sunwa" instead of "sanwa" label, others aren't. 

[FenderBender]

Looks like a very nice meter. $80-90 Made in Japan. Seems like it could have potential. Though, now that I think of it, there are some other things I think I'd like to buy before getting an analog meter, but I really am interested in getting one.

[bradleytron]

Thanks everyone. I've taken all of your suggestions to heart. I figure if I'm going to buy an analog meter, I don't think I will buy a $300 Simpson but something cheap...though I don't know who even makes a good analog meter these days.

May I suggest that you approach the school, principal and or head of the science department, and ask them if they would be willing to give one to you. Your point being that they have never been used by the school.

[FenderBender]

Probably could just put in my backpack and leave. *cough*...No one would miss it. 

I'm not so sure about that. The principal of my school is very hard headed. I don't think he'd even consider it. My electronics teacher who is also my physics teacher is a cool guy though. I might ask him about it, but I think he'd be one to say "You'd have to check with my supervisor" or something.

But I never really thought about that.