Products > Test Equipment
AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter
stj:
interesting thing in the manual for people who bitch about the fuses,
the maximum voltage for current readings is 36v DC or 25v AC.
ocw:
--- Quote ---Two meters in series Carry current the same
--- End quote ---
Yes, but Ohm's Law says that the current through both will down from what it was before the meters were inserted. Again, I'm talking about the typical currents which I measure during repair and alignment. Those are almost always not constant currents.
The attachment shows how I label all of my similar meters.
Mark Hennessy:
--- Quote from: ocw on July 16, 2017, 05:21:12 pm ---
--- Quote ---
--- Quote ---Putting two meters in series makes the limitations of both meters influence the other.
--- End quote ---
Howcome? :-//
--- End quote ---
Instead of just the shunt resistance of the "tested" meter limiting the current, you will have the two shunt resistances in series limiting the current. I want a meter which won't change the actual current when it is inserted. The added shunt resistance will lower the current unless you are measuring a constant current. I don't often measure that when I am using the meter for repairs or alignment. That's when I want it to be accurate.
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That isn't the "limitations of both meters influencing the other". Rather, that's the extra resistance of the measurement meter slightly reducing the current in the circuit to the DUT.
But how is that a problem when the other meter is telling you the test current?
I've no idea what the voltage is, and I've no idea how accurate the 50 ohm resistance of my Wavetek 162 is. But it doesn't matter. As I said, I simply want to see how the DUT compares to my existing meters.
I adjust the amplitude of the Wavetek until the measurement meter says something close to the sort of current I want. Then I write down both numbers, and calculate how close they are. Simple. I'm aware of the limitations, but I'm no voltnut.
BTW, how does your method account for the non-linear resistance of the fuse?
ocw:
--- Quote ---That isn't the "limitations of both meters influencing the other". Rather, that's the extra resistance of the measurement meter slightly reducing the current in the circuit to the DUT.
--- End quote ---
Let's take a specific example. I took my voltage reference which has a 5.00377 volt output and connected my 100 ohm 0.005% resistor (Y1453100R000V9L) in series with it. On my Agilent 34401A meter I measured 47.4017 mA. Under identical circumstances my AN8008 measured 49.9 mA! That's because the shunt resistance on the 34401A is 5.022 ohms as compared to 0.0301 ohms on the AN8008. If you put both meters in series I would expect both meters to read about 47.4 mA due to the 34401A's shunt resistance. Which method is more meaningful and/or accurate? I want to know how accurate the current measurement is compared to the current without the meter inserted (50.0377 mA).
In the above situation the AN8008 was more accurate than my relatively expensive 34401A. However, if you correct the 34401A's reading, its accuracy is -0.016% as compared to the AN8008's accuracy of
-0.2452%. I'm trying to find the meter which has the best accuracy without requiring me to use my "slide rule."
boffin:
--- Quote from: stj on July 16, 2017, 06:05:20 pm ---
--- Quote from: boffin on July 16, 2017, 05:50:36 pm ---The AN8008 looks great except the two missing mA ranges. Does anyone know if the AN8002 suffers from the same fault?
--- End quote ---
take a look
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Many thanks, looks like no missing ranges.
* 0-60mA (10u)
* 0-600mA (100u)
* 0-6A (1m)
* 0-10A (10m)I'll probably pick up a couple of these as giveaways for my next course at work.
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