DMM Recommendations?

[CJ]

Fluke makes good test leads, the rest is mostly a name,

i use a 15 dollar RichMeters 101 from China

batteries last forever, has C meter, Freq meter,

gets dropped an average of 4 times a day , still working, don't want to drop a 1000 dollar fluke 4 times a day,

 

[Khron]

gets dropped an average of 4 times a day , still working, don't want to drop a 1000 dollar fluke 4 times a day,

Perhaps..?

 

[CJ]

and for keyboards i use the Casiotone MT-100.

 

[Whoops]

i use a 15 dollar RichMeters 101 from China

And that's a pretty good DMM.
90% of the members of this forum would not need anything more advanced than that for a DMM

 

[Brian Roth]

This discussion reminds me that it's been well over 10 years since I had my Fluke 87V calibrated.

I've done "informal" comparisons with a local 187 and a (model forgotten) Fluke brought here by a guy doing service on the cutting lathe. DC volts from an AAA battery, measuring VAC wall voltage from Evergy, a few Ohms measurements of a few 1% metal films.

Measurement comparisons were within a gnat's whisker.....but NOT traceable to any standards organization.

For hobbyists, if you're within 10 or 20%...close enough for rock and roll. And, as I'm now semi-retired I don't have to answer questions from out-of-town studio clients on the "traceability" of my instruments. A few years ago I was doing a large studio project out of state and the owner was "Beyond Thunderdome" in his obsession that (for instance) 0 dBm cals were within 0.0000000000000001 <g> dBm. Argue all you want about that insanity....but he was paying my invoices.

Nowadays....hey +/1 tenth or quarter dB seems OK to me <g>.

Bri

 

[Newmarket]

I noticed over the years my B&K 2880A doesn't seem to go out of cal compared to those auto ranging flukes I've used in different sectors. Flukes seem to have issues with small negative dc voltages in high impedance circuits, but I stayed away from them and the only time I had to use them was working for someone where that level of accuracy wasn't important. Back in the CRT television repair days, Flukes were useless because they loaded down the circuitry.

The only thing I found that I send in to cal every 3 years or so was my oscilloscope because its voltage readout would go out of cal from the waveform. But that was just a small annoyance for me, and it never effected critical alignment when I would use it calibrate audio compressors and analog stereo processors, because I would read from the waveform scale that I cal before using.

Agree that much equipment is fine well beyond Cal' Due date. tbh we often delay putting kit in for cal' if we are in the middle of using it on a particular project.
But to rely on that long term you need your own test equipment to check.
And if your 'pro' environment is one where you need/choose to demonstrate compliance with Cal standards then you need to have that done by an appropriately registered service eg UKAS registered in UK.
Interesting note on the Flukes. Work generally involves high voltage / high impedance circuits. But metering for that is generally via compensated voltage dividers into eg Keithley mains powered bench DMMs. Or HV scope probes into Tek' or LeCroy DSO.

 

[Brian Roth]

Hmmmm...decades ago the "factory service manual" voltages assumed a 20000 Ohms/Volt Simpson or equivalent (check out the Sams Photofacts)...except for specific cases which required a VTVM.

Bri

 

[Graham Nystrom]

Quality for price- check out Amprobe. Mine can read capacitace and frequency so its great for audio. Cheers yall!
Graham

 

[Cqwet Dbdfte]

An eye-popping site for DMM review:
https://lygte-info.dk/info/DMMReviews.htmlHigh end meters:
https://lygte-info.dk/info/DMMHigh-end UK.html

 

[Cqwet Dbdfte]

Who needs 6 1/2 digits?
I never did... I some times felt the need for measuring resistance down to 0.01 ohm or up to several gigaohms, but never with an accuracy that goes beyond 2 digits.

A hi rez DMM is extremely useful in troubleshooting PCBs with shorts. Apply a low voltage to the circuit, maybe 1V or much less, then go probe for voltage gradients, shorts have the lowest voltage. Easier than using resistance checking where probe contact resistance gets in the way.

Checking other parts and traces for small voltage dropouts can point to PCB-, solder joint-, and component errors.

Measuring low levels of AC signal, a 6.5digit DMM with good AC response can measure down to -111dBu.

Any 10Mohm DMM also works great in checking leakage currents in caps, diodes and transformers. Use ACV-range to check insulation from mains from AC-neutral to DC out. Divide result by 10^6. Same method for capacitor leakage, use DCV range.
Unsurprisingly many wallwarts have poor isolation.

 

[abbey road d enfer]

A hi rez DMM is extremely useful in troubleshooting PCBs with shorts. Apply a low voltage to the circuit, maybe 1V or much less, then go probe for voltage gradients, shorts have the lowest voltage. Easier than using resistance checking where probe contact resistance gets in the way.

Checking other parts and traces for small voltage dropouts can point to PCB-, solder joint-, and component errors.

Measuring low levels of AC signal, a 6.5digit DMM with good AC response can measure down to -111dBu.

Any 10Mohm DMM also works great in checking leakage currents in caps, diodes and transformers. Use ACV-range to check insulation from mains from AC-neutral to DC out. Divide result by 10^6. Same method for capacitor leakage, use DCV range.
Unsurprisingly many wallwarts have poor isolation.

I understand all you say, but you are confusing sensitivity, resolution, accuracy and precision.
Who ever needs 6 digit resolution on dB measurements? 31/2-digit is usually enough.
Or for continuity? Even for leakage?
Although high sensitivity is required for the latter two, a basic two-digit display is plenty.
And for AC leakage, one needs to know if it's safe, tingling, jolting or lethal. 2-digit is enough.

 

[Cqwet Dbdfte]

Read it one more time. Will you get to -110dBu with 3.5 digits?
Did not say 6.5 digits for leakage, or anything about continuity. Not a word.
"Accuracy" in its ISO9000 official sense is derived from traceable confirmations to a national standards lab. Not confusing.
"Who needs ..." maybe not you.

 

[abbey road d enfer]

Read it one more time. Will you get to -110dBu with 3.5 digits?

Why not? If the sensitivity is adequate.
Let's say the full scale is -60dBu. -110 is 50dB below full scale. A 3-digit display would indicate -50.0 with a resolution of 0.1dB
Of course, if the full scale is 0dBu, you need 3 digits to display -110 (resolution 1dB), or 4 digits to display -110.0 (resolution 0.1dB).
Indeed if you want to measure -110dBu with some accuracy (basically implying the last digit is ascertained) with an instrument that has a +20dBu full-scale, you need more resolution, actually 2000 points or 3 1/2 digits.
It's just metrology 101.

 

[abbey road d enfer]

Did not say 6.5 digits for leakage, or anything about continuity. Not a word.

Well, you wrote "A hi rez DMM is extremely useful in troubleshooting PCBs with shorts."
No. You need high sensitivity. You want to measure microvolts, you need sensitivity, not resolution. Who cares if your PCB trace is 10 or 11 (or 9) microohm?

 

[Cqwet Dbdfte]

Resolution is different than "sensitivity"?
Haha

 

[abbey road d enfer]

Resolution is different than "sensitivity"?

Yes.
https://electronics.stackexchange.c...-between-sensitivity-and-resolution-of-an-smuhttps://digilent.com/blog/accuracy-precision-resolution-and-sensitivity-what-do-they-mean/

Haha

Laughing at your own ignorance doesn't make you look good.

 

[Cqwet Dbdfte]

Sensitivity of a voltmeter as in 20kohm/volt? Down to a level, the typical 3.5digit DMM's 0.2V range maybe has 100uV resolution with a percentage error plus a few digits?

20log(0.775/0.000001)=?

Show me a 3.5 digit DMM that does 1uV.

Who cares about microOhms in PCB traces? Well some do.
Using my essentially 4-wire method will find problems in PCB, maybe not what you are dealing with.
I also have that Keithley old book and also bought a benchtop 6.5 digit Keithley over 25 years ago.

 

[abbey road d enfer]

Sensitivity of a voltmeter as in 20kohm/volt?

Sensitivity as in what voltage (or current or whatever is measured) results in full scale indication. That's the definition.

Down to a level, the typical 3.5digit DMM's 0.2V range maybe has 100uV resolution with a percentage error plus a few digits?

Yes, and? Why would you want to measure 100uV with a meter set at 0.2V range?

20log(0.775/0.000001)=?

117.78, but what this has to do with the subject. You're mentioning 0.2V range, so 0.775 is out-of-range.

Show me a 3.5 digit DMM that does 1uV.

A meter with a 1mV range can do that easily. There's a good reason why test instruments have range selectors.

Who cares about microOhms in PCB traces?

You do.

Using my essentially 4-wire method will find problems in PCB, maybe not what you are dealing with.

Your method is a Kelvin connection, that allows to measure micro ohms without the error due to contact resistance of the probes.

 

[Cqwet Dbdfte]

Your definition of "range" falls apart with an auto ranging 6.5 digit DMM that captures signals between 1kV and a 1uV, without over-ranging.

Which 3.5digit DMM has a 1mV range?

Limiting your vision will obscure details that could be meaningful. Staying in old paradigms will just confirm your bias.
Get stronger glasses.

 

[Cqwet Dbdfte]

"...The sensitivity of an analog multimeter is given in units of ohms per volt. For example, a very low-cost multimeter with a sensitivity of 1,000 Ω/V would draw 1 mA from a circuit at full-scale deflection..."
https://en.m.wikipedia.org/wiki/Multimeter