A look at the Uni-T UT210E

[flywheelz]

Is there some benefit to have it range down at a different value than range up value? e.g. 1900 vs 2200, 5800 vs 6200

When you are testing from zero going up in range, you still get the full 6000 count but when going down, you only get 2000 count.

example: when reading a changing voltage (charging cap etc) it counts from 1.000 to 2.000 .... 5.000 - 6.000 then 07.00 - 08.00 but when going down, it had to go 08.00 - 07.00 .... 04.00 - 03.00 - 02.00 then 1.000. I hope you get what I mean. 

Yes I get what you are saying. I set my to range up at 6200 (@12h-13h) and range down at 5900 (@14h-15h) just like they do it on UT211E. After some thinking, I believe they set different limits so that it will not constantly change the range up/down when you are measuring varying voltage at the limit you set.

[hgg]

Update with mains voltage.

Again, values on the left were fluctuating because of unstable mains voltage.
The measurements on the right were from a crappy UPS with a modified 'sine'wave. 
Virtually spot on with the Brymen.

I don't see a problem with the 8000 counts.   
If it does have a problem with higher voltages like 400V and above I wouldn't mind
because I am not using anything close to that. 

I only need to fix the down ranging.

[djQUAN]

Update with mains voltage.

Again, values on the left were fluctuating because of unstable mains voltage.
The measurements on the right were from a crappy UPS with a modified 'sine'wave. 
Virtually spot on with the Brymen.

I don't see a problem with the 8000 counts.   
If it does have a problem with higher voltages like 400V and above I wouldn't mind
because I am not using anything close to that. 

I only need to fix the down ranging.

It may be fine with sine waves, try higher crest factor waveforms.

Re. down ranging - have you tried what I suggested? It worked for me.

[PedroDaGr8]

Update with mains voltage.

Again, values on the left were fluctuating because of unstable mains voltage.
The measurements on the right were from a crappy UPS with a modified 'sine'wave. 
Virtually spot on with the Brymen.

I don't see a problem with the 8000 counts.   
If it does have a problem with higher voltages like 400V and above I wouldn't mind
because I am not using anything close to that. 

I only need to fix the down ranging.

It may be fine with sine waves, try higher crest factor waveforms.

Re. down ranging - have you tried what I suggested? It worked for me.

"Modified Sine Wave" isn't actually a sine wave at all, it is a stepped square wave. The name was invented by UPS manufacturers to make the performance sound less bad on the UPS description

[hgg]

Here is an example of a high crest factor waveform.

Just made a 20x op amp amplifier and fed in the output from my signal generator.
Below is one of its built in waveforms but amplified as well. 

Its a 22.6Vpp waveform with a crest factor of around 5.4   That was the highest I could achieve.   
You can see that the difference from the Brymen is just 0.1Volts

The moral of the story is that Siglent 1102CML does not have a crest factor function...   

[tronde]

In the VC-921 thread linked to earlier, indman (who is on the Russian forum as well) says there are problems with ACV if the frequency is above 400Hz or there are high frequency harmonics present. Nothing strange about that. I guess the APC300 mentioned suffers from harmonics. I have 8000 counts on my VC-921 and no strange behaviour on 50Hz sine wave, but we are sacrificing crest factor when we extend the counts from the 6000 specified in the data sheet.

[hgg]

400Hz and how many volts?
I've tested the previous 22.6VAC waveform up to 2Khz with similar results.

[tronde]

400Hz and how many volts?
I've tested the previous 22.6VAC waveform up to 2Khz with similar results.

I understand that the error will increase when you are closer to end-of-scale. Try the same waveform and close to 8V and see if you get trouble.

[hgg]

That was the highest I could go with such a high crest factor waveform.
Maybe someone else can test it and report back.

djQUAN, I will make the final change @ 14h &15h but I need to solder 3 wires every time
I make a change because of the way I am reading the EEPROM.

So, did you check the down ranging?  Does it stay at 8000 counts when the voltage starts decreasing?

[flywheelz]

So, did you check the down ranging?  Does it stay at 8000 counts when the voltage starts decreasing?

I checked the down ranging and it works beautifully. Mine set at 5900 and as soon as voltage drops below that level it switches to 3 decimal digits. I suggest you set the down ranging slightly lower (100 to 300mV) than up ranging so that if you measure fluctuating 8 volts the meter won't be going crazy.

[hgg]

Great, I will wait a bit more just in case any new mods appear... and then finalize it.   

[tronde]

That was the highest I could go with such a high crest factor waveform.

If you can get 22.6VAC you should be able to get a lower value of the same waveform too?
With 22.6 I assume you are using the 80.00 range. Reduce the voltage to something below 8.000V and see if you get some error then when using the 8.000 range. The chip does not know about the absolute value of the voltage. It cares about percentage of available counts. With 22.6 and 80.00 range you have a huge headroom up to the 120.00 that is believed to be max count for the TRMS converter.

[hgg]

22.6V was the peak to peak value of the waveform, not the RMS which was 2.4V.
I can raise the RMS voltage but then the crest factor will decrease which was the
point in the first place.

I might give it another try to see if I can get a crest factor of 3 and RMS of around 8V.

[tronde]

22.6V was the peak to peak value of the waveform, not the RMS which was 2.4V.
I can raise the RMS voltage but then the crest factor will decrease which was the
point in the first place.

I might give it another try to see if I can get a crest factor of 3 and RMS of around 8V.

From your HEX-dump it seems like you have added the mV-ranges? Then you should have 800.0mVAC. Can you reduce the voltage to fit that range?

[hgg]

That's a good idea.   
I will try it.

[hgg]

Just tried to do it but I got strange behavior in the mV range from the UT210E and the Brymens.

The waveform was just a pure (positive) sinewave at 60hz.
The reference multimeter that was agreeing with the oscilloscope was the UT136C...   
Probably because of its mV auto ranging.  But have a look at the other multimeters.
(sorry for the bad image quality)

@ 30mV



@104mV



@178mV



@223mV



@301mV we lose the UT61E probably because of its 22000 counts limit. 
It correctly displays -OL-



@406mV



@520 mV we lose both the UT210E and the Brymen BM869s.
The UT210E behaves here as a 4000 count meter!
The Brymen BM869s stays always below 440mV (50.000 count?) and even worse it does not display any warning!



@603mV



@722mV we also lose the Brymen BM235 as its a 6000 count meter, but again no warning
of the error!



@920mV the UT136C is the only one still displaying the correct value.



With a high crest factor things got more ugly.


So, the UT210E after the mod behaves as a 4000 count meter in the mVAC range...

The UT61E was the most well behaved which is to show that its still one of the best
low budget multimeters for low voltage electronics.  That accuracy drift though... 

The thing to note was that the Brymens displayed false readings without any warning.
* FAIL *  for the expensive Brymens...   

[tronde]

I just did som testing with an modified and an unmodified VC-921 believed to use tha same chip as UT-210E. I used 60Hz sine just as you did.

The modifed (8000 counts plus added functions) shows some strange behaviour in the 800mV range (06H). The unmodified instrument has 400mV native. Between about 150mV and 500mV it shows some 5 - 10mV too much, decreasing at higher value. I did not see anything strange around 4000 as you did, and in 8.000VAC I did not notice any errors from 0 - 8.000V.

I have added the 80/800mV ranges as well (02H). No errors there. The unmodified VC-921 did not show any errors in the native 400mV range.

I know that VC-921 and UT-210E are not the same instrument but this is strange. We know that the DTM0660 chip is programmable in addition to the settings stored in EEPROM. UT-210E does not have RS232 for instance. It seems like somethong goes wrong when we hack too much.

[ssanmor]

Hello, guys.
I also have this clamp, and was very happy with it. Until, for some reason, one day it stopped working.
It doesn't read DC currents in the clamp, and also it doesn't read DC voltages at the probes. Also, when I try to read resistance, I always get around 2 kohm, even with the probes disconnected.

 And yes, I replaced the batteries.

I have opened it and found nothing obvious. Any chance to fix it? In any case, I found a new one for around 16$ in eBay so I ordered it, but would like to know how to fix it anyway.

Thanks!

[Fleetz]

Wow you guys have taken this the UT210E to another level.

I just want a basic AC DC clamp meter mainly for measuring household appliances eg AC, cooktops, appliances etc for confirming power consumption for basic power use audits. Also some low DC amp < 1A

Not looking to do the mods so looking for a reviewer that just uses the UT210E in standard configuration and not for commercial use. Is it ok in standard configuration for reasonably accurate and repeat applications?

It the 2000 count a big issue?

[Zbig]

Nothing wrong with just using it as is, it's not mandatory to hack it In my observation, the least significant digits are more useful for visualizing there is a change than for their absolute values. FWIW, I didn't hack mine and don't intend to. Still wondering why haven't I got one earlier, though

[The Soulman]

Wow big fail for the brymens, to high input capacitance?? 

[milamber]

Just tried to do it but I got strange behavior in the mV range from the UT210E and the Brymens.

The waveform was just a pure sinewave at 60hz.
The reference multimeter that was agreeing with the oscilloscope was the UT136C...   
Probably because of its mV auto ranging.  But have a look at the other multimeters.
(sorry for the bad image quality)

[...]

The UT61E was the most well behaved which is to show that its still one of the best
low budget multimeters for low voltage electronics.  That accuracy drift though... 

The thing to note was that the Brymens displayed false readings without any warning.
* FAIL *  for the expensive Brymens...   

I was so close to ordering the BM869s as a successor to my 25 year old Metex M-3650B (3 1/2 digits (or less by today ), 2000 counts) ...
Do the Brymens only behave wrong like that in AC Mode?

Maybe I should go with the UT61E (German GS version) until the perfect DMM hits the market
(The BM869s lacks in unit Data logging, the UT61E lacks temperature and drift stability , Flukes are out of my price range)

[hgg]

Do the Brymens only behave wrong like that in AC Mode?

Yes, only in mVAC mode.

I don't know if a fix is possible.
I tried to contact them for schematics and they did not even reply...

[The Soulman]

Wow big fail for the brymens, to high input capacitance?? 

Probably not.
Just happen to be reading the data sheet of a Fortune FS9922 DMM-3 chip it says:

VB is the bias current input in IC. The increase off R1 reduce the current in IC,
but the shortage of bias current will affect the input range of AC measurement.

Don't know what chips brymen uses but if they are similar chips also from Fortune
this smells like it.

[Lightages]

Do the Brymens only behave wrong like that in AC Mode?

Yes, only in mVAC mode.

I don't know if a fix is possible.
I tried to contact them for schematics and they did not even reply...

I have been unable to recreate the results you are showing with your Brymen meters. Seeing as both are misbehaving I am going to assume it is something wrong systematically with your setup. I tested some of my meters, BM869S, BM525S, BM257, UT136B, UT139C, and a Keithley 197 each connected separately one by one and none of these meters showed any problems like you demonstrated. The output was from a Siglent SDG1025.