Author Topic: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter  (Read 299241 times)

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Offline Andrey_irk

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #125 on: July 15, 2017, 01:45:19 pm »
Did someone measure temperature stability of the meter? Will it be within specs at say 0C or +40C?
Although I think it is possible to just put in better resistors if you really need it. The reference seems to be OK.

Square wave generator is useful for checking different speakers and buzzers. I'm surprised nobody pointed it out.

P.S. It's funny to see people here discussing a thread on kazus.ru. But yeah, their discussion seems to be the most comprehensive one on that matter. I can try to translate something for you if google fails.
 

Offline Fungus

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #126 on: July 15, 2017, 01:48:26 pm »
Being required to get a different meter when a reading which you are peaking goes above 1 mA doesn't make sense.

True, but owning a second meter is almost a requirement anyway and this one measures everything else] about as well a a 7.5 digit bench meter (according to Dave's video).

For $17-18? Owning one of these is a no-brainer. I'd almost go as far as saying "it's a UT61E killer for a quarter of the price".

(until the next one comes along - this is ANENG's third meter this year based on this chipset)


Square wave generator is useful for checking different speakers and buzzers. I'm surprised nobody pointed it out.

I did, in the main thread.  :popcorn:
« Last Edit: July 15, 2017, 02:14:50 pm by Fungus »
 

Offline tronde

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #127 on: July 15, 2017, 03:45:50 pm »

yes, but isn't the chipset/hardware difference only that "square wave output" feature on AN8008 (ZT109)? and everything else is exactly the same? I mean (AN8002 + EEPROM hack to 9999 counts) is equal to (AN8008 - digital square wave feature) or there is real difference in accuracy? (BTW, on first glance even both PCBs of AN8008 and AN8002 looks very very similar).

You can't get a 9999 reading of AC voltage with the DTM0660 chipset. Around 8500 seems to be the limit, depening of the crest factor.


Reading and writing the PROM in DTM0660 is easy. Even I have managed that.

https://www.eevblog.com/forum/testgear/hacking-the-victor-vc-921/


 

Offline tronde

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #128 on: July 15, 2017, 04:27:47 pm »

 And ... what the hell is this? I never saw that on a meter before.


The datasheet says battery test for 9V and 1.5V. I guess 40mA load for 1.5V and 24mA for 9V.
 

Offline matura713

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #129 on: July 15, 2017, 04:46:14 pm »

You can't get a 9999 reading of AC voltage with the DTM0660 chipset. Around 8500 seems to be the limit, depening of the crest factor.


thanks, that means DM1106EN is really upgraded version of DTM0660...
 

Offline Fungus

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #130 on: July 15, 2017, 04:59:59 pm »
The datasheet says battery test for 9V and 1.5V. I guess 40mA load for 1.5V and 24mA for 9V.

More useful than a square wave output!  :)

(Now I need one of those as well.  :scared: )


PS: Do you think I should send one to Batteroo for their test lab?
« Last Edit: July 15, 2017, 05:02:19 pm by Fungus »
 

Offline kalel

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #131 on: July 15, 2017, 05:16:08 pm »
The datasheet says battery test for 9V and 1.5V. I guess 40mA load for 1.5V and 24mA for 9V.

More useful than a square wave output!  :)

(Now I need one of those as well.  :scared: )


PS: Do you think I should send one to Batteroo for their test lab?

That is the cheapest meter I see with battery tester ($3.7).
I just wonder where do you install the fuse as suggested:


Edit: Maybe the little spot below the screw on the right? - Looks like a diode sign.

Speaking of small meters, this one has a nicer (larger) display:


But otherwise it's has no battery testing.
« Last Edit: July 15, 2017, 05:26:26 pm by kalel »
 

Offline Fungus

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #132 on: July 15, 2017, 05:57:18 pm »
I just wonder where do you install the fuse as suggested:


The PCB trace goes up under the buzzer. I expect that's where it is.  ;)

I like the way you can take the back off without stressing the wires going to the buzzer. A buzzer holder costs money, it's good to see they aren't cutting any corners. :popcorn:
 
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Online SeanB

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #133 on: July 15, 2017, 06:08:46 pm »
They probably could get the complete piezo with the casing and leads cheaper than the cost of the bare piezo, the added mouldings in the case dies along with the 3 stakes or drops of glue and the 2 springs.
 

Offline Mark Hennessy

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #134 on: July 15, 2017, 06:32:56 pm »
As somewhat referred to previously, the AN8008 is a poor meter to use between 1 - 100 mA.  I just completed my detailed accuracy verification of the lower current readings.  For an approximately 1 mA current reading I had the choice of 989.8 uA (1.01% low due to the 100.561 meter insertion resistance) or 1.0 mA.  Yes, that's two digits, 10% error represented by the least significant digit.  That's the best resolution possible just above 1 mA.  The -1% uA error continued down to around 200 uA.  When the reading was corrected for the added resistance, the uA accuracy was typically below 0.1%.

The DC voltage reading accuracy was typically 0.06%  The resistance reading accuracy was typically below 0.3%.  Most of my resistors used for accuracy verification were rated at 0.01% accuracy.

More tests tomorrow.

I got slightly better results from mine.

In uA, the error varied between -0.25% and -0.47%.

In mA, mine met the 1.5% spec. The worst error was at 5mA, where I got 4%, but of course, 1 count is 2% at 5mA. Factor in the "3 counts" part of the specification, and 5.2 is indeed OK for 5.0mA. Elsewhere, it was comfortably within 1%.

Down at the sub-10mA end of the scale, the voltages from the 0.01 ohm shunt are tiny, resulting in 10uV per milliamp - so they're really taking advantage of the high voltage resolution/sensitivity to achieve this. The AN8002 certainly does better in the 1-10mA range, but of course lacks uA.

Personally, I would have preferred it if they'd not bothered with the square wave output, and used the switch position for mA, with a different shunt.
 

Offline Mark Hennessy

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #135 on: July 15, 2017, 06:41:09 pm »
Square wave generator is useful for checking different speakers and buzzers. I'm surprised nobody pointed it out.

Sadly not as useful as you might think...

As I mentioned earlier, the square wave comes from quite a high source impedance (about 2k). So by the time you've fed that into an 8 ohm loudspeaker, there's hardly any voltage there. I tried a very sensitive 15 ohm speaker, and you have to hold it to your ear to hear anything from it.

However, it does work on piezo sounders :-+
 

Offline deflicted

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #136 on: July 15, 2017, 06:56:36 pm »
Square wave generator is useful for checking different speakers and buzzers. I'm surprised nobody pointed it out.

Sadly not as useful as you might think...

As I mentioned earlier, the square wave comes from quite a high source impedance (about 2k). So by the time you've fed that into an 8 ohm loudspeaker, there's hardly any voltage there. I tried a very sensitive 15 ohm speaker, and you have to hold it to your ear to hear anything from it.

However, it does work on piezo sounders :-+

Noob question: I seem to recall reading somewhere that square waves are bad for speakers because the flat parts look like DC, and DC ruins speakers. And supposedly that's why clipping is bad as well, because it starts to look like a square wave, which is too much like DC. Not being an electronics guy, I just thought, hmm, well sounds plausible. Granted, I'm guessing it probably doesn't matter much for tiny piezo speakers and such. Also, I'm guessing this little multimeter square wave doesn't have nearly enough power to ruin a speaker, regardless.

But is there some truth to this, or is this just one of those audiophile myths that get thrown around?
« Last Edit: July 15, 2017, 06:58:51 pm by deflicted »
 

Offline tronde

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #137 on: July 15, 2017, 07:02:19 pm »


P.S. It's funny to see people here discussing a thread on kazus.ru. But yeah, their discussion seems to be the most comprehensive one on that matter. I can try to translate something for you if google fails.
That is great offer, really! What would be nice for us non-russian speaking people is if you could give a hint when something interesting is discussed there. Google translate is usually OK if you know what you are translating, but quite often interesting things are "hidden" in a lot of text so it goes under the radar. One thing is that the language is different, but when the alphabet is different too, it becomes difficult to spot such things.
 

Offline b_force

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #138 on: July 15, 2017, 08:22:58 pm »
It's just to bad for the current, which blows my mind because the voltage ranges are fine.

I was just wondering, wouldn't be an idea to develop a small daughter board to provide the correct input protection and maybe some extra extra tweaks to get a better current range?

Offline ocw

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #139 on: July 15, 2017, 08:56:45 pm »
Quote
It's just too bad for the current...

Place a 1 ohm resistor across a Pomona 1330-2 (or similar), plug that into the AN8008 ground and voltage inputs, connect the current measurement wires to the top of the 1330-2 and the mV reading = mA.

It would be nice if that wasn't required, however.

Adding a battery test function could be done the same way.
 

Offline b_force

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #140 on: July 15, 2017, 09:02:04 pm »
If this meter is lying around with its false ratings and someone picks it up to use it where they need the real protection because they see the marks, it could kill them or injure them severely.
I seriously never understand this statement??  :-//

Worst thing that could happen is a spark inside a plastic case (= multimeter).
That's absolutely not enough to "KILL" someone.

In my whole professional career I have blown up many things, have seen sparks everywhere and have been shocked more times than my hands can count.
It hurts, but for normal healthy human beings, not walking bare foot on wet soil and not being pinched close to the heart, it's absolutely nonsense to say that this is "super dangerous".

The most dangerous part is that scare up people when it happens and in that moment maybe fall off a ladder.
That could even happen with a decent professional meter.

Only thing you can say, is that it's very inconvenient and 'dangerous' in a sense that you simply don't know what you can rely on.
For someone who is using this multimeter behind a fused line (like at home or a desk), it's not much of a deal.
For someone who is working professionally with high power high voltage lines, which aren't always directly fused, it's a whole different story.
But in these situations you're only allowed to use certified gear anyway. 
 
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Offline ocw

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #141 on: July 15, 2017, 10:05:44 pm »
I finally got inside of the meter since the AC current measurements don't seem very stable.  I haven't seen a poor connection yet which might be causing that.  Regarding:

Quote
Place a 1 ohm resistor across a Pomona 1330-2...

There is already a 1 ohm resistor inside of the meter ready to serve that purpose.  The 100 ohm shunt resistance for uA current measurement actually consists of a 99 ohm resistor in series with a one ohm resistor.  With a little rewiring...

The meter must have been changed from mA current to uA, robbing the full resolution mA measurement capability.  On the switch side of the circuit board the voltage, uA, etc input is labeled "V/R/F/mA/Hz/C."  Yes, that is mA and C, not uA and square wave.

The board is labeled ZT109 on the switch side.  See: http://szzotek.com/en/col.jsp?id=144

I'll have to look for other secrets. 
 

Offline ocw

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #142 on: July 16, 2017, 12:05:34 am »
Quote
I finally got inside of the meter since the AC current measurements don't seem very stable.

While the two digit ammeter for 1 - 10 mA DC readings might have limited value, it is of no use for AC readings in that range.

While I had reasonable accuracy on the AC uA readings from 10 to 1000 uA, things fell apart when I tried to read 1000 uA as 1 mA AC.  The AN8008 showed zero mA for that measurement.  My next test measurement was at 3.3 mA.  The AN8008 generally stayed at a reading of zero with an occasional jump up only to soon return to zero.

My next step is at 10 mA.  By then I had a steady reading which was 8% low.  At 30 mA the meter became useful with a reading which was only 1% low.  By 75 mA and above the meter's surprising accuracy returned with the accuracy typically below 0.2%.
 

Offline evavaTopic starter

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #143 on: July 16, 2017, 08:56:35 am »
Quote
I finally got inside of the meter since the AC current measurements don't seem very stable.

While the two digit ammeter for 1 - 10 mA DC readings might have limited value, it is of no use for AC readings in that range.

While I had reasonable accuracy on the AC uA readings from 10 to 1000 uA, things fell apart when I tried to read 1000 uA as 1 mA AC.  The AN8008 showed zero mA for that measurement.  My next test measurement was at 3.3 mA.  The AN8008 generally stayed at a reading of zero with an occasional jump up only to soon return to zero.

My next step is at 10 mA.  By then I had a steady reading which was 8% low.  At 30 mA the meter became useful with a reading which was only 1% low.  By 75 mA and above the meter's surprising accuracy returned with the accuracy typically below 0.2%.

IMHO, it is very common that TRMS measurement at most multimeters works only at about >5% of the range.
It is usually stated in manual.
Only exception is thermo TRMS converter at some precision meters.

This is the very problem of this meter AC current measuring in these missing current ranges. If only this TRMS converter could be switched off sometimes manually, that would help.
 

Offline alm

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #144 on: July 16, 2017, 09:04:40 am »
The true RMS error is usually due to a DC offset in the RMS converter. This offset disappears at higher values because sqrt(ACV^2 + offset^2) tends to ACV if ACV >> offset (which is also why you can not subtract the offset by measuring the output with shorted inputs). So I would indeed not expect good performance near the bottom of the range.

Bypassing the TRMS converter is rarely supported (exception: some meters for the military since they still have old procedures that require an average-responding meter). I guess you could take out the TRMS chip and replace it by a precision rectifier, but that would destroy any TRMS ability and seems like an awful lot of work for this cheap meter.

Offline Fungus

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #145 on: July 16, 2017, 09:06:13 am »
In mA, mine met the 1.5% spec. The worst error was at 5mA, where I got 4%, but of course, 1 count is 2% at 5mA. Factor in the "3 counts" part of the specification, and 5.2 is indeed OK for 5.0mA. Elsewhere, it was comfortably within 1%.
I'd be happy with that.

Personally, I would have preferred it if they'd not bothered with the square wave output, and used the switch position for mA, with a different shunt.
Or move the lower ranges up by a factor of 10. How many people really need to measure nanoamps?

As I mentioned earlier, the square wave comes from quite a high source impedance (about 2k). So by the time you've fed that into an 8 ohm loudspeaker, there's hardly any voltage there. I tried a very sensitive 15 ohm speaker, and you have to hold it to your ear to hear anything from it.

Something else I won't have to bother to check when mine finally arrives.  >:(

(I should have stopped reading this thread a few pages ago)

Noob question: I seem to recall reading somewhere that square waves are bad for speakers because the flat parts look like DC, and DC ruins speakers.
Only true if there's a lot of amps available. In this case there isn't, there's a 2k resistor between the battery and the speaker.

It can be a good idea to add a capacitor in series with the speaker to prevent long periods of DC from damaging the speaker (the capacitor will charge up after a short period of time and block the DC).



(image chosen randomly from google)
« Last Edit: July 16, 2017, 09:09:55 am by Fungus »
 

Offline exe

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #146 on: July 16, 2017, 09:21:03 am »
Edit1: Reading the small print, that meter needs a weird 12V battery.

I have a similar unit, it uses a 12V battery, same used in many car remotes. Wouldn't call this an issue, but battery costs like half of DMM. I replace it every two-three years or so. It's only 2000 counts, but this is good-enough for most my purposes.
 

Offline kalel

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #147 on: July 16, 2017, 09:28:24 am »
Edit1: Reading the small print, that meter needs a weird 12V battery.

I have a similar unit, it uses a 12V battery, same used in many car remotes. Wouldn't call this an issue, but battery costs like half of DMM. I replace it every two-three years or so. It's only 2000 counts, but this is good-enough for most my purposes.

On eBay, the cheapest I could find is about $1 for 1 or $2 for 5 batteries (I guess shipping comes into play). That said, I guess it shouldn't be far too much more expensive locally, if you search around. So, even the cheapest is probably about 1/4 of the meter. But 9v batteries are not much cheaper (if not more expensive) and with these cheap meters, a battery is always a good part of the price of the meter. What can you do. Maybe you could modify it to work with a cheap 3.7v Lipo, but I'm not sure if that's a good idea or not.
« Last Edit: July 16, 2017, 09:34:45 am by kalel »
 

Offline Fungus

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #148 on: July 16, 2017, 09:31:59 am »
It's just to bad for the current, which blows my mind because the voltage ranges are fine.

It's always a good idea to own more than one meter anyway, so that:
a) You can take measurements that need two meters (eg. power)
b) You can see two values in a circuit simultaneously (can be useful, eg. with batteries so you can watch the battery voltage under load)
c) You can occasionally check meter readings against each other. If you see a weird reading, how do you know the problem isn't the meter? There's no substitute for a second opinion, even if you own a Fluke 87V (in fact I'd have more overall confidence in my readings if I owned two of these than if I owned a single Fluke)

I was just wondering, wouldn't be an idea to develop a small daughter board to provide the correct input protection and maybe some extra extra tweaks to get a better current range?

Or ... if this is super-important to you then make sure your second/third meter has a suitable mA range. It's simply not worth building "daughter boards" when an AN8002 costs $15.
 

Offline Mark Hennessy

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Re: AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
« Reply #149 on: July 16, 2017, 09:39:03 am »
Quote
I finally got inside of the meter since the AC current measurements don't seem very stable.

While the two digit ammeter for 1 - 10 mA DC readings might have limited value, it is of no use for AC readings in that range.

While I had reasonable accuracy on the AC uA readings from 10 to 1000 uA, things fell apart when I tried to read 1000 uA as 1 mA AC.  The AN8008 showed zero mA for that measurement.  My next test measurement was at 3.3 mA.  The AN8008 generally stayed at a reading of zero with an occasional jump up only to soon return to zero.

My next step is at 10 mA.  By then I had a steady reading which was 8% low.  At 30 mA the meter became useful with a reading which was only 1% low.  By 75 mA and above the meter's surprising accuracy returned with the accuracy typically below 0.2%.

Mine is better than yours here as well. I wonder if I'm lucky, you're unlucky, or this is just the sort of sample-to-sample variation we have to expect at this price point?

On uA AC, mine was spot-on when compared with a Fluke 87V. Really, no more than 2 or 3 counts away in both ranges, right down to the smallest signals. That impressed me, to be honest.

On mA AC, then yes, it's not brilliant at very small currents:

Fluke 87VAN8008Error
1.03mA0.0mA-
3.00mA0.0mA-
4.01mA2.0mA-50.1%
5.06mA3.6mA-28.6%
6.06mA4.8mA-20%
7.07mA6.1mA-13.7%
8.05mA7.3mA-9.3%
10.08mA9.5mA-5.8%
15.01mA14.6mA-2.7%
20.11mA19.7mA-2%
30.56mA30.2mA-1.2%

So mine comes into spec at 30mA, and seems to hold it pretty well above that. I didn't try very high currents as that would have meant plugging up an amplifier, etc...

I tested with a 100Hz sine wave from an old Wavetek 162 function generator. My readings were stable within a count at all points - I wonder if noise was an issue for you?

Instinctively, I would treat all AC readings with suspicion when so near to the bottom of the range, but for beginners who pick up this meter, it's good to highlight this. Obviously the AN8002 is the one to buy for measuring currents in this region - buy one of each  :-+ The fact they're different colours helps (well, me at least) when doing something involving multiple meters, which is why if I bought a second BM235, I'd get the "vanilla" version with the red holster...

Oh, earlier I mentioned 1.5% for the current spec. That's for the AN8002 - I'd picked up the wrong manual. Sorry :palm: The AN8008 is a bit tighter, at 1%+3 (and 0.8%+3 on uA) on DC. However, I don't think that changes anything I said earlier. Meanwhile, on AC, it's 1.2%+3 on mA and A, and 1%+3 on uA.
« Last Edit: July 16, 2017, 09:40:35 am by Mark Hennessy »
 


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