Are there any handheld DMMs that read ACV & DCV simultaneously?

[Electro Detective]

After all of this discussion, why is it necessary to measure both AC and DC on the same meter? If you only have one meter maybe but if you are working on electronics you want at least two meters anyway, three or four even better.

Connect the meters in parallel, set one on DC and the other on AC. Then you can see both components and with the added ability to adjust the AC range independently from the DC range so you can see smaller ripple. Make sure the meter being used has the better AC bandwidth and is TRMS.

Whilst that is what usually ends up happening for those in the know with an arsenal of meters, the thread is titled:    Are there any handheld DMMs that read ACV & DCV simultaneously?   

[chickenHeadKnob]

Does such a beast exist?  It would be great for working on power supplies.

For me, extreme precision isn't needed; lower cost is the more desirable feature.  Thanks for any suggestions you may have!

Do you want to measure overall efficiency ie. AC power in vs DC power out? In which case separate meters. Or do you want to measure PARD ? (periodic and random deviation -Stupide acronym, not my invention).  If you are looking at transient response, ripple and other noise on a DC output you want a DSO, not a hand held that is only giving you 4 samples per second.

[bitseeker]

In the US, you can also get Brymen meters under the Greenlee brand. I have the DM-820A and it works great for seeing AC ripple voltage while measuring DC output voltage.

The V and mV of dm820a are separated, Therefore, In dual display mode, it may not be enough resolution to measure ripple with V range.

Sure, depends what you're measuring. Works fine for my use.

[bitseeker]

I have the DM-820A and it works great for seeing AC ripple voltage while measuring DC output voltage.

No, you can not measure mV AC RMS ripple when on 50V range (common 10V-30V power supply).

Even if your meter is not overloaded big DC offset, AC RMS values are only defined FOR ABOUT > 5% of range, which in this example is about > 2.5V AC RMS.
Even 1% is only 500mV, and even on switch power supplies 30mV ripple you can not see and measure.
mVolt (AC RMS) readings have no value on 50V range!

That's a tall order for a handheld DMM. You'd certainly need more resolution (high-end Brymen?).

[Lightages]

After all of this discussion, why is it necessary to measure both AC and DC on the same meter? If you only have one meter maybe but if you are working on electronics you want at least two meters anyway, three or four even better.

Connect the meters in parallel, set one on DC and the other on AC. Then you can see both components and with the added ability to adjust the AC range independently from the DC range so you can see smaller ripple. Make sure the meter being used has the better AC bandwidth and is TRMS.

Whilst that is what usually ends up happening for those in the know with an arsenal of meters, the thread is titled:    Are there any handheld DMMs that read ACV & DCV simultaneously?   

I answered the OP's question, and offered an alternative option. Nothing wrong with that.

[nanofrog]

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[Lightages]

Guys, please lets keep the thread steered towards what the OP asked. 

FWIW it's possible to get what s/he wishes in both a hand-held or bench meter. Given the recent-ish shut-down of ITT, the GW Instek 8251A benchtop DMM is still one heck of a deal IMHO (5.5digit meter, dual display).

That is completely dishonest of you to fabricate a quote from me that I didn't say. It might be something I might think but it is a total fabricated lie. Please edit your post and apologize..

[Simon]

I've given him a couple of weeks to think about "with great power comes great responsibility"

[evava]

I have the DM-820A and it works great for seeing AC ripple voltage while measuring DC output voltage.

No, you can not measure mV AC RMS ripple when on 50V range (common 10V-30V power supply).

Even if your meter is not overloaded big DC offset, AC RMS values are only defined FOR ABOUT > 5% of range, which in this example is about > 2.5V AC RMS.
Even 1% is only 500mV, and even on switch power supplies 30mV ripple you can not see and measure.
mVolt (AC RMS) readings have no value on 50V range!

That's a tall order for a handheld DMM. You'd certainly need more resolution (high-end Brymen?).

What I am trying to say is that none resolution matters in this case, because of RMS converter, everything under 5% (maybe 1%) of range is not valid.
That's all.
So IMHO you can not measure ripple and DC voltage of the power supply on one meter shown on dual display mode.

[Vtile]

I have the DM-820A and it works great for seeing AC ripple voltage while measuring DC output voltage.

No, you can not measure mV AC RMS ripple when on 50V range (common 10V-30V power supply).

Even if your meter is not overloaded big DC offset, AC RMS values are only defined FOR ABOUT > 5% of range, which in this example is about > 2.5V AC RMS.
Even 1% is only 500mV, and even on switch power supplies 30mV ripple you can not see and measure.
mVolt (AC RMS) readings have no value on 50V range!

That's a tall order for a handheld DMM. You'd certainly need more resolution (high-end Brymen?).

What I am trying to say is that none resolution matters in this case, because of RMS converter, everything under 5% (maybe 1%) of range is not valid.
That's all.
So IMHO you can not measure ripple and DC voltage of the power supply on one meter shown on dual display mode.

Unless it does have multiple front-ends doing the measurement.

[alm]

What I am trying to say is that none resolution matters in this case, because of RMS converter, everything under 5% (maybe 1%) of range is not valid.
That's all.
So IMHO you can not measure ripple and DC voltage of the power supply on one meter shown on dual display mode.

Assuming you are talking a traditional analog RMS-to-DC converter, like the AD636/7, they will have an offset that will increase the error and the lower end of the scale. This does not make the readings garbage as soon as they dip below 5%, but it does mean the meter may not meet its accuracy spec there. For ripple measurements I find this not as big of a deal, especially for troubleshooting, since you are often looking for order of magnitude differences due to a dead cap or open rectifier diode. On my Fluke 189, the AC offset in dual display mode on the 5 V range is about 5mV, so when measuring 10 mV, the error would be about 11% (which is about is pretty good for a ripple measurement), and for 20 mV the error is down to 3%. Note that the offset adds to the measurement value as the sum of squares. Obviously these are not guaranteed specs, but I find this a long way away from "unusable".

This is not an issue for the more modern technique of digitizing the waveform and the calculating the RMS value like used on modern Keysight bench meters. But I doubt you'll find that in any handheld, and certainly not in a $100 one.

[glarsson]

This is not an issue for the more modern technique of digitizing the waveform and the calculating the RMS value like used on modern Keysight bench meters. But I doubt you'll find that in any handheld, and certainly not in a $100 one.

Isn't that the method used in all the cheap ($20) handhelds with true RMS?

[IanB]

Isn't that the method used in all the cheap ($20) handhelds with true RMS?

Yes, but you will get digitization error with small signals (only a few bits of resolution available)?

[Lightages]

These concerns about the accuracy of a small AC component reading is why I suggested it better to use two meters. It is helpful though to have a sanity check all on one meter at least.

I have found to very hard to find a meter with dual display and can display both AC and DC together for less than around $175.

[IanB]

For good accuracy the meter should split the signal and measure the AC and DC components through different measurement paths. Then each part of the signal can use optimal scaling in the A-D converter.

It occurs to me that the 121GW must have two measurement paths to do current and voltage simultaneously. So potentially that hardware might be able to do the same with AC+DC? I wonder...?

[bitseeker]

Assuming you are talking a traditional analog RMS-to-DC converter, like the AD636/7, they will have an offset that will increase the error and the lower end of the scale. This does not make the readings garbage as soon as they dip below 5%, but it does mean the meter may not meet its accuracy spec there. For ripple measurements I find this not as big of a deal, especially for troubleshooting, since you are often looking for order of magnitude differences due to a dead cap or open rectifier diode.

Exactly. For my use, the dual display works just fine for troubleshooting. It's caught ripple when I wasn't expecting it, which is a great help (Aha! Well, lookee here.). Once you see there's some kind of AC showing up on a DC rail, you just switch to AC mode to measure the true magnitude of the problem.

But this all goes back to knowing what any gear can and can't do. When in doubt, test it.

[joeqsmith]

Just for a bit of a sanity check, shown with a 35mV RMS sine wave riding on top of 21VDC.    In PIC4, you can see that the BM869s has a 10mV resolution and is about half.  The UT181A is showing 26mV which is at least something.  The old Fluke 189 is the closest.    None of them are great and again, it's only 100Hz.   

[joeqsmith]

Keeping the levels fixed and changing the AC frequency from 100Hz to 10KHz, the UT181A really starts to fall off.   The Fluke 189 hangs right in there.  So not real accurate at these levels but still could be very useful.   Just keep the 181A away from any static..

[hgjdwx]

Keeping the levels fixed and changing the AC frequency from 100Hz to 10KHz, the UT181A really starts to fall off.   The Fluke 189 hangs right in there.  So not real accurate at these levels but still could be very useful.   Just keep the 181A away from any static..

Why don't you try the 10khz dual display mode with the bm869s and METRAHIT? In addition, the ripple of 35mv is also some high, the general power supply is not so high, you can try 10mv.

[hgjdwx]

And I've found that almost all handheld meters, including the vast majority of desktop meters, are very slow in dual display mode, And no exceptions have been found.

[joeqsmith]

Keeping the levels fixed and changing the AC frequency from 100Hz to 10KHz, the UT181A really starts to fall off.   The Fluke 189 hangs right in there.  So not real accurate at these levels but still could be very useful.   Just keep the 181A away from any static..

Why don't you try the 10khz dual display mode with the bm869s and METRAHIT? In addition, the ripple of 35mv is also some high, the general power supply is not so high, you can try 10mv.

Because I felt the two counts the BM869s was showing in the AC secondary window was too far down making it pointless.   I asked Vtile early on if they wanted a specific test ran.  Evava was the only one tossing out some numbers so this is what I went with.     Going to 10mV is only one count.  It's not going to improve things..

I was not aware that the Gossen could make this measurement.   

The only other meter I have that can show the AC and DC content separate is the TPI 194II which sadly was damaged during testing and can not be used to make this measurement. 

[joeqsmith]

And I've found that almost all handheld meters, including the vast majority of desktop meters, are very slow in dual display mode, And no exceptions have been found.

I would have no idea what very slow means to you.   To me, maybe once an hour.   I'm guessing there are meters that are faster than that. 

[hgjdwx]

And I've found that almost all handheld meters, including the vast majority of desktop meters, are very slow in dual display mode, And no exceptions have been found.

I would have no idea what very slow means to you.   To me, maybe once an hour.   I'm guessing there are meters that are faster than that.

Sorry for my English, I mean the update speed of the data, is the time from the probe contact test point to the meter to show the stable reading.

[bitseeker]

Mine is slower in dual display mode than single, but it's still faster than switching back and forth. For the awareness it provides, it's worth having.

Of course, none of my handheld DMMs beat the speed of my bench DMMs. Right tool for the job, etc.

[evava]

Can you please elaborate on this?

On my Fluke 189, the AC offset in dual display mode on the 5 V range is about 5mV, so when measuring 10 mV, the error would be about 11% (which is about is pretty good for a ripple measurement), and for 20 mV the error is down to 3%. Note that the offset adds to the measurement value as the sum of squares. Obviously these are not guaranteed specs, but I find this a long way away from "unusable".

I would like to know more about this.
For example, if you RELed that offset before measurement, what would be the error then (and the measured/shown value)?
And why Fluke does not recommend or rather forbids to REL the offset for the sake of accuracy?

And I noticed now, that in your example on Fluke 189 you are on range 5V, what about error on range 50V, would that be still

a long way from "unusable"

?
I see the tests that Joe performed (thank him), I too tried to measure ripple of some wall warts with Fluke 289 (and UT181a) paralel with scope, and I came to the conclusion that this (measurement of ripple with MM on dual display) is not the way to do it .