Author Topic: Measuring nanoamps and below like a Ninja  (Read 91929 times)

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Offline bsw_m

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Re: Measuring nanoamps and below like a Ninja
« Reply #325 on: May 20, 2022, 03:49:09 pm »
10pF and 100pF air capacitors with sapphire insulators that used in differentiator of a EK1-6 and NK4-1 low current calibrators.
A 10pF capacitor is used for ranges down to 1E-13A.
A 1pF and 0.1pF capacitors are used for ranges down to 1E-17A (sorry no photo).
« Last Edit: May 20, 2022, 07:05:17 pm by bsw_m »
 
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Offline shodan@micron

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Re: Measuring nanoamps and below like a Ninja
« Reply #326 on: May 21, 2022, 10:49:42 am »
Looks like, this weekend be shared for capacitors testing...

I found pack of 1nF K71-7 Polystyrol caps, it shows good results:
0.33fA at 0V after hold 15 minutes.
4.32 fA at 0V->7V change and hold 5 minutes.
What means on 10 mV/s ramp it be less 0.05% error.
(1nF at 10mV/s = 10pA; 4.32fA leakage it is 0.0432% of 10pA)
« Last Edit: May 21, 2022, 10:52:19 am by shodan@micron »
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Offline bsw_m

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Re: Measuring nanoamps and below like a Ninja
« Reply #327 on: May 21, 2022, 11:49:16 am »
In the EK1-6 NK4-1 low current calibrators for that range has used 2pcs K72P-6 560pf in parallel connection.
May be this type capacitors is best for that range: better DA and less leakage. I don`t know about long term stability - need to be tested, but i think these capacitors is reliable in stability for that duty.
« Last Edit: May 21, 2022, 12:08:43 pm by bsw_m »
 

Offline shodan@micron

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Re: Measuring nanoamps and below like a Ninja
« Reply #328 on: May 21, 2022, 04:17:25 pm »
used 2pcs K72P-6 560pf in parallel connection.
Unfortunately, my 1.2nF 1kV K72P-6 shows unacceptable results in any connections(any side, any conditions, any guarding scheme).
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Offline bsw_m

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Re: Measuring nanoamps and below like a Ninja
« Reply #329 on: May 21, 2022, 04:53:35 pm »
Unfortunately, my 1.2nF 1kV K72P-6 shows unacceptable results
What the parameter is unacceptable?
Leakage, DA or may be other?
 

Offline shodan@micron

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Re: Measuring nanoamps and below like a Ninja
« Reply #330 on: May 21, 2022, 04:57:23 pm »
They shows more 100fA after 15minute hold at 0V. After change 0V to 7V it also shows hundred femtoamps... I've test 10 pcs or so...
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Offline shodan@micron

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Re: Measuring nanoamps and below like a Ninja
« Reply #331 on: May 22, 2022, 07:57:26 pm »
Today i did first capacitance reference and accuracy tests. There is 1nF reference based on K71-7 Polystyrol capacitor.


I use "NJ100S"(it is low quality, low precision LCR) for transfer unit of capacitance from my standard to reference on 50 Hz test frequency.
And compare reference with resistance standard P4030.

First test is P4030(1000.041MOhm) at 1.00005V = 1.000009nA.
Keysight B2985A shows 1.000059nA, it means B2985A error is +0.005%.

Second test is 1nF reference(1.004426nF) with 9.95594E-01V/s ramp = expected current is 1.00000nA.
Keysight B2985A shows 1.000544nA, it means error is (+0.053% - +0.005%) = +0.048% trough resistance and capacitance method.

Results not an ideal... but when current drop down to pA ranges that error is acceptable.

And finally, these is my toys:
« Last Edit: May 22, 2022, 07:59:31 pm by shodan@micron »
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Online Kleinstein

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Re: Measuring nanoamps and below like a Ninja
« Reply #332 on: May 22, 2022, 08:26:50 pm »
The dielectric absorption makes the capacitance to go down when the frequency goes up.
The measurement at 50Hz is somewhat faster than the use with the ramp.

So part of the difference can be due to the DA of the PS cap. The usual tabulated amount of DA for PS is at some 0.05%, which may be a coincidence because of the different time scales and not all PS caps are the same.
 

Offline shodan@micron

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Re: Measuring nanoamps and below like a Ninja
« Reply #333 on: May 22, 2022, 08:37:16 pm »
The dielectric absorption makes the capacitance to go down when the frequency goes up.

You're definitely right!!!
When i transfer unit of capacitance on 1kHz frequency error be much higher, around 0.1%.

I do experiment's with transfer unit though "charge method", but still not ready to share final report. That transfer method can help increase precision.
Anyway.... I'm think, 50Hz transfer with 0.05% accuracy it is acceptable.
« Last Edit: May 22, 2022, 08:41:19 pm by shodan@micron »
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Online Kleinstein

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Re: Measuring nanoamps and below like a Ninja
« Reply #334 on: May 22, 2022, 09:20:17 pm »
0.05 % accuracy for 1 nA looks already quite good. This is especialy knowing that there a known effect to cause a bias in that direction.
 

Offline shodan@micron

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Re: Measuring nanoamps and below like a Ninja
« Reply #335 on: May 23, 2022, 02:19:54 am »
About GLIN v.2:
Still in progress... Output PCB ready(LPF + programmable amplifier + protection circuits), digital PCB and front panel arrived.
« Last Edit: May 23, 2022, 02:33:41 am by shodan@micron »
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Offline shodan@micron

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Re: Measuring nanoamps and below like a Ninja
« Reply #336 on: May 26, 2022, 06:07:17 pm »
Local PCB factory delivered today last PCBs and stencils.
Internal power source updated to tantalum capacitors.
In this weekend must be delivered these tantalum capacitors and i hope to assembly all PCBs together :popcorn:

« Last Edit: May 26, 2022, 06:22:59 pm by shodan@micron »
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Offline shodan@micron

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Re: Measuring nanoamps and below like a Ninja
« Reply #337 on: June 01, 2022, 06:05:22 am »
For attoamps Ninja: Low current reference of VNIIFTRI Metrology institute, 1976y.

https://ampnuts.com/wp-content/uploads/2022/06/technika_electrometrii2_translation.pdf

A.M.Ilukovich "Technique of electrometry"
© Energiya Publishing house, 1976.
Pages 262-263
« Last Edit: June 01, 2022, 06:07:20 am by shodan@micron »
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Offline shodan@micron

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Re: Measuring nanoamps and below like a Ninja
« Reply #338 on: June 01, 2022, 10:52:23 am »
UPD: "Indirect method" shows into V7-45 performance verification procedure:
--------CUT----------
On subranges 10-10...10-14A use the differentiator D1 of the EK1-6 calibrator, and on subrange 10-15A - the differentiator D3.

As in the differentiator D3 the so-called non-stationary differentiating capacitor, is used by electrode of the output of the differentiator and the input electrode of the V7-45 voltmeter, the differentiator D3 demands preliminary calibration.

To carry out calibration of the differentiator D3 in the following sequence:
1 - check the indication of the V7-45 voltmeter on the subrange 10-14A, giving from the EK1-6 calibrator via the differentiator D1 current 10-14A.
2 - Replace the differentiator D1 with the differentiator D3 and repeat check on the subrange 10-14A, giving current from the calibrator to EK1-6 of the 9.999∙10-15. Rotation of the axis "CALIBRE" resistor on the differentiator D3 to achieve that indications of the V7-45 voltmeter in both cases did not differ more, than for the 1%.
Then to pass to check of the error of measurement on subrange 10-15A. To set controlled current and high-speed performance according to tab. 9.4.
--------CUT----------
It very similar to VNIIFTRI method, except small changes. That means, UUT must be tested on point 10-14A with classic "stationary dual electrode capacitor". After that directly on input installs non-stationary differentiating capacitor, and tuned on highest ramp speed x10 exactly to same current 10-14A. It means non-stationary differentiating capacitor tuned as closer as possible to:
Cnon-stationary=Cclassic/10.
After that ramp speed is slow down to normal value, and performance verification of range 10-15A and less can be started.
« Last Edit: June 01, 2022, 11:39:57 am by shodan@micron »
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Offline guenthert

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Re: Measuring nanoamps and below like a Ninja
« Reply #339 on: June 01, 2022, 11:50:21 pm »
     I noticed that the Russian word for voltage has been translated into 'tension'.  I've seen the same in other documents (google-)translated from Chinese.  I found that amusing, as the German word for both tension and voltage is 'Spannung'.
 

Offline TimFox

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Re: Measuring nanoamps and below like a Ninja
« Reply #340 on: June 02, 2022, 02:40:23 am »
"Tension" is sometimes used for voltage in English, especially in the phrase "high tension".
 

Online Atomillo

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Re: Measuring nanoamps and below like a Ninja
« Reply #341 on: June 02, 2022, 07:07:20 am »
In Spanish too. "Alta tensión" (high tension) is a lot more common than "Alto voltaje" (high voltage).
In all other cases they are used pretty much interchangeably.
 

Online RoGeorge

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Re: Measuring nanoamps and below like a Ninja
« Reply #342 on: June 02, 2022, 07:16:13 am »
In Romanian, too, it's tension.  Usual (and academic, too) is to say, for example for AC voltage, "tensiune alternativă", as opposed to "voltaj alternativ".  "Voltaj alternativ" just sounds wrong, though the word "voltaj" is listed in our dictionary as a neologism, imported from the French "voltage".
« Last Edit: June 02, 2022, 07:22:33 am by RoGeorge »
 

Offline MegaVolt

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Re: Measuring nanoamps and below like a Ninja
« Reply #343 on: June 02, 2022, 08:11:09 am »
     I noticed that the Russian word for voltage has been translated into 'tension'.  I've seen the same in other documents (google-)translated from Chinese.  I found that amusing, as the German word for both tension and voltage is 'Spannung'.
Yes. The translation into Russian of these two words sounds the same.
 

Offline 2N3055

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Re: Measuring nanoamps and below like a Ninja
« Reply #344 on: June 02, 2022, 11:04:20 am »
In Romanian, too, it's tension.  Usual (and academic, too) is to say, for example for AC voltage, "tensiune alternativă", as opposed to "voltaj alternativ".  "Voltaj alternativ" just sounds wrong, though the word "voltaj" is listed in our dictionary as a neologism, imported from the French "voltage".

Same in Croatian.  Official name is "napon" which is tension. There is a colloquial word "voltaža", a voltage, but that is used very rarely and is usually a sign you don't really know much about electricity .... :-)
 

Offline TimFox

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Re: Measuring nanoamps and below like a Ninja
« Reply #345 on: June 02, 2022, 02:04:11 pm »
In elementary physics class (English-speaking), one of the tricky bits for new students to understand is "tension", for example the force in a string in an "Atwood machine" (two unequal weights connected by a string running on two pulleys).  That is the same meaning as in "tensile strength" of a material being stretched.  Therefore, English-speaking physicists usually will not use "tension" for a voltage.  God knew what he was doing at Babel...
 

Online RoGeorge

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Re: Measuring nanoamps and below like a Ninja
« Reply #346 on: June 02, 2022, 02:18:05 pm »
We have that, too, tension as a mechanical stretch.  ;D
https://www.etymonline.com/word/tensile
https://www.etymonline.com/word/tension

Same word (tensiune) in Romanian can be used for electric tension, mechanical tension, suspense (e.g. in a movie scene), sometimes the word is used to denote a stressful situation, psychological pressure, blood pressure (popular way of saying "high blood pressure", aka hypertension, in Ro is to say somebody "have tension"), etc, while saying voltage (instead of tension) usually indicates the speaker doesn't know much about electricity, just like in Croatian.
« Last Edit: June 02, 2022, 02:27:55 pm by RoGeorge »
 

Offline SilverSolder

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Re: Measuring nanoamps and below like a Ninja
« Reply #347 on: June 02, 2022, 08:52:35 pm »

Scandinavian languages also call it "tension"...   seems popular!

The concept of "electrical tension" does kind of make sense in English too, but it just isn't customary to call it that.

 

Offline TimFox

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Re: Measuring nanoamps and below like a Ninja
« Reply #348 on: June 02, 2022, 09:11:00 pm »
In careful American physics usage, one says "electric potential", sometimes the antique term "EMF",  not to be confused with "potential energy".
In English, there are too many meanings for "tension", leading to ambiguity.  https://www.yourdictionary.com/tension
 

Offline SilverSolder

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Re: Measuring nanoamps and below like a Ninja
« Reply #349 on: June 02, 2022, 09:17:31 pm »

"Electric tension" seems to be fair game, though?  It is unambiguous and seems to be actually used, if you google it!
 


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