It didn't take very long after the pocket calculator was brought to market for the slipstick to be obsolete. And yet, even with the advent of the DMM, the VOM is still being marketed. Simpson and Triplett (and several others) are not only continuing to market the VOM but also still making improvements on them. It has at least moved away from vacuum tube models but why is it still marketable other than for nostalgia reasons?
VOM Vs. DMM
- Thread starter SamR
- Start date
The only reason I can think of is that an analog meter allows you to more easily follow slow changes in the reading, such as adjusting a voltage or looking for a null.
There are some DMMs (such as some Flukes) that have a bar-graph readout at the bottom of the display along with the digital, for that very purpose.
Otherwise It would seem to fall in the same category as to why vinyl records and tube amps still have a market.
Simpson’s pitch is that it is easier to follow “fluctuations and trends”, and since the meter doesn’t use a clocked chip it doesn’t generate RFI. They say, “professionals have long known that the Simpson VOM is far superior to a DMM for following fluctuations and trends.”
If you were a pro, you would have long known this! You are revealed as a noob! I never would have guessed. You fake knowing what you are talking about very well.
I don’t know who writes their ad copy but they need to rethink it.
Some swear by analog VOMs to measure Variable Frequency Drive output because it is so noisy. They say DMMs can't faithfully measure (average) the chopped up AC.
I'm not convinced that is true, but if it is, it applies to more than just VFDs. Anyone measuring noisy signals might prefer a VOM.
Personally I just carry a high quality DMM and trust what it tells me. I would not carry an additional, larger, instrument unless I absolutely needed measurement accuracy that was better than what my DMM offers, and I don't absolutely need that, nor do I believe a VOM would provide it.
I'm not convinced that is true, but if it is, it applies to more than just VFDs. Anyone measuring noisy signals might prefer a VOM.
Personally I just carry a high quality DMM and trust what it tells me. I would not carry an additional, larger, instrument unless I absolutely needed measurement accuracy that was better than what my DMM offers, and I don't absolutely need that, nor do I believe a VOM would provide it.
They are great for relative HV measurements as they are just about impervious to EMI/RFI when things start to go bad during a repair.
It has a tube, it's time for Simpson.
Mr. Fluke is sleeping under that cart, in safety.
It's a choice of readout from long experience of building things that control HV.
The nostalgia reason is my analog meter is trusted not to lie about dangerous voltages because of some digital circuit lockup.
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Please define VOM...
schmitt trigger
- Joined Jul 12, 2010
- 900
In 2019, before Covid, I visited Tokyo’s Akihabara district. Although it is now a far cry from the 1980s “electric town”, I still found a shop which sold analog equipment. I purchased a Samwa analog VOM, partly from nostalgia but also because it was the last one which had the coveted “Made in Japan” sticker, the remaining ones were now made in Thailand.
Seldom use it, any DMM is leaps and bounds better. However, when measuring the voltage drop of a DC motor’s current shunt, no DMM would give a stable result. But this lowly VOM did.
The motor’s brushes were sparking… a lot. The noise was confusing the DMMs.
Seldom use it, any DMM is leaps and bounds better. However, when measuring the voltage drop of a DC motor’s current shunt, no DMM would give a stable result. But this lowly VOM did.
The motor’s brushes were sparking… a lot. The noise was confusing the DMMs.
volt, ohm, milliammeter. The generic name for analog multimeters, while DMM is the generic name for digital multimeters.
As already noted, analog meters can perform better is some noisy environments, including environments with the potential (no pun intended) to damage a digital meter.
Having a physical needle reading can also be quicker for people to assess and reduce potential interpretation errors. You know where you want the needle to be, so you know if it is there (or at least very close) at a moment's glance. With a digital meter, you have to be looking for a specific number and think at least enough to determine if the actual number is close enough to what you want. You can also get a better feel for the size and shape of signal fluctuations (within limits) with an analog meter movement compared to changing numbers on a digital display.
Overall, I prefer DMMs for most applications, in large part because they generally perturb the circuit significantly less than most VOMs. But there are times that I'm glad I still have my old VOM available (and more times when I wish I would make the effort to dig it out instead of just getting by with the DMM).
OK I wasn't sure, so we're actually talking about analog multimeters, because its easy to find examples of Digital VOMs out there.
Last VOM I had was probably late 70s to early 80s and made the mistake of loaning it to a guy who worked as an instrument tech. He didn't even bother to tell me when he returned it that he had burnt its internals to a crisp and I didn't bother to ask just how the hell he managed to do it as he apparently didn't have a clue. I've never paid a bit of attention to the bar graph on my DMMs and consider it pretty much useless other than a marketing gimmick. OK, I get the point of noisy or fast changing signals being easier read on the VOM as I've had that problem a few times. So, I've bought a nicely used Simpson 260 series 5. No parallax mirror (which my old one had) but if I need something that accurate, I have a 5-digit bench meter or a selection of handheld DMMs.
schmitt trigger
- Joined Jul 12, 2010
- 900
Konnichiwa!
Forgot to add that it has a 1.5V battery tester, which tests the battery under load to provide a better assessment of the battery’s health.
Forgot to add that it has a 1.5V battery tester, which tests the battery under load to provide a better assessment of the battery’s health.
There's certainly no standard nomenclature. As you can see in this description, two interpretations for VOM are given. But I think that if you could survey the usual way that the terms VOM and DMM are used, you would find that the analog versus digital distinction dominated by a wide margin.
Early VOM's were valve instruments and therefore typically had high impedance inputs however the move to solid state reduced that much and the moden DMM has much better input impedance yet the need for instruments to take readings and NOT affect the DUT has many bench meters now offer a 10G input impedance.
Moving coil meters and such had best 20 or 30k/V so dragged high impedance current sources down yet only a few decades ago they were the industry standard....today we can do better, much better.
DMM designed for mainly electrical wiring have low-z modes because that high impedance input can fool you.
https://www.fluke.com/en-us/learn/blog/digital-multimeters/dual-impedance-digital-multimeters
Sure but LoZ is a special requirement not in most of the multitude of meters available today.
The bench meters we do don't have it however a few hundred Ohms across the test leads serves a similar purpose.
LoZ is an important requirement for a large portion of the professional meter buying community called electricians.
Even HF has a model with it.
https://www.harborfreight.com/dm1000-electricians-hvac-contractor-trms-multimeter-64019.html
- LoZ low input impedance: helps prevent false readings due to ghost voltage
