Products > Test Equipment

AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter

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Mark Hennessy:

--- Quote from: ocw on July 16, 2017, 03:39:48 pm ---Putting two meters in series makes the limitations of both meters influence the other.

--- End quote ---

Howcome?  :-//



--- Quote from: ocw on July 16, 2017, 03:39:48 pm ---I connect a 0.01% accuracy resistor in series with a voltage measured with 0.0015% accuracy and measure the current with a single meter to see how that compares with the current based on Ohm's Law.  That's what I call real world current.

--- End quote ---

So how do you account for the resistance of the shunt, fuse, wiring and connectors?

I make no claims here - I just want to know how it compares to my existing meters...

ocw:

--- Quote ---Putting two meters in series makes the limitations of both meters influence the other.

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.


--- Quote ---So how do you account for the resistance of the shunt, fuse, wiring and connectors?
--- End quote ---

The AN8008 has a 100 ohm shunt resistor (99 & 1 ohm in series) for measuring uA currents.  I don't use that figure when correcting for its insertion.  I use the 100.561 ohms which I measured across the AN8008's two terminals.  I add the resistance of any connecting wires if that is significant.  Similarly, while there is a 0.01 ohm resistor for mA/A currents on the AN8008, I use the 0.0301 ohms which I measured across its terminals.

I don't need to play these correction games when I'm using my ADA4530-1 current to voltage converter or my electrometers.

boffin:
The AN8008 looks great except the two missing mA ranges.  Does anyone know if the AN8002 suffers from the same fault?

Gandalf_Sr:
There was a young man named Kirchoff
Who said there's something I'm sure of
Two meters in series
Carry current the same as
Cos the current flowing onto one node is the same as the current in the other of

Caveat <I just got back from the bar>  :popcorn:

stj:

--- 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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