Products > Test Equipment
Device for nA Measurements ?
Nicole01:
Hello Everyone,
i would like to know how you make Measurements in the nA Range ?
Which Devices can you recommend here ?
You can't do that with a normal Multimeter.
Even with most Benchtop Multimeters it is not possible.
What Experiences have you here ?
Many Thanks
Nicole
bdunham7:
There are many variations, but I use one of these:
Nicole01:
Thanks for your Help and the Info.
I'm looking for a newer Device.
It would be good if it was already Digital :-+
bdunham7:
Well, as I said there are many variations. At the other extreme from my very old model, there are:
https://www.tek.com/en/products/keithley/low-level-sensitive-and-specialty-instruments/series-6400-picoammeters
It depends on what your specific requirements and budget are. The active inputs on typical picoammeters result in a low voltage drop (burden voltage) across them, only a few mV in the case of my ancient 414A. If that doesn't matter and you have a higher-voltage high-impedance source you want to measure, a 10M input voltmeter actually works with 1V = 100nA. Also, there are some cheap converter units like the uCurrent from EEVBlog's Dave Jones and the Current Ranger, a sort of knock off. I don't know much about those two, but they've been discussed here at length and you can search for them.
Performa01:
Most DMMs with 10 Mohms input impedance can be used for this in principle.
Just use the voltage range, e.g. 200 mV instead of the current ranges. This becomes a 20 nA range and you can measure down to 10 pA with a 20000 count meter.
Some (especially true bench) meters have an unexpected high input current up to 1 nA. You can detect this by measuring the open circuit voltage with 10 Mohm input impedance; thus the meters own input current. If this is anywhere above 50 pA (= 0.5 mV), then the meter isn't usable for this purpose.
Of course, the "correct" way to do this is using an electrometer; this allows you to measure down to the femtoamperes...
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