Author Topic: Measuring nanoamps and below like a Ninja  (Read 24820 times)

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Offline chuckb

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Re: Measuring nanoamps and below like a Ninja
« Reply #100 on: November 14, 2018, 09:43:21 am »
With +31 V bias the MEDER HI05-1A66 had 10.5 fa of leakage across the contacts. With -31 V bias it had -12.5 fa of leakage. So the average leakage at 31 V bias is 11.5 fa. This equates to over 2000 T ohms isolation resistance. I have previously measured the contact to coil leakage current being 1/3 of the contact to contact leakage current. This relay has been sitting on my bench for several month with no cleaning before this test. Hope this helps.
 
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Offline chuckb

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Re: Measuring nanoamps and below like a Ninja
« Reply #101 on: November 16, 2018, 03:23:38 pm »
I have also tested the  COTO 9012. This is a very small relay for less than $10 USD. The contact isolation resistance is 4000 T ohms. The coil to contact resistance is 1000 T ohms at 100V.

 

Offline Vtile

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Re: Measuring nanoamps and below like a Ninja
« Reply #102 on: November 30, 2018, 07:52:14 am »
With my Marconi / Meratronic Meratester I'm in like a Flyn. Sensitivity (noticeable relative change) is somewhere in region of 50 fA.  ^-^




 

Offline branadic

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Re: Measuring nanoamps and below like a Ninja
« Reply #103 on: December 01, 2018, 01:28:05 am »
We do have one of those brown bricks, Keithley 617. Nice piece of kit. I ordered some Ohmite high value 1% metal oxide resistors (100meg, 1G, 10G) and build a small setup with the resistors mounted on teflon standoff. After all these years without being calibrated the readings on the meter are still consistent.

-branadic-
Fluke 8050A | Prema 5000 | Prema 5017 SC | Advantest R6581D | GenRad 1434-G | Datron 4000A | Tek 2465A | VNWA2.x with TCXO upgrade and access to: Keysight 3458A, Keithley 2002, Prema 5017 SC, 34401A, 34410A, Keithley 2182A, HDO6054, Keysight 53230A and other goodies at work
 

Offline TiN

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Re: Measuring nanoamps and below like a Ninja
« Reply #104 on: December 23, 2018, 07:50:05 am »
Accidentally bought myself Xmas gift...  :o



Source is Keithley 6221.

Oh well... I hope buying not broken modern equipment will not become a habit.  :-//
YouTube | Chat room | Live-cam | Have documentation to share? Upload here! No size limit, firmware dumps, photos.
 
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Offline Inverted18650

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Re: Measuring nanoamps and below like a Ninja
« Reply #105 on: December 23, 2018, 11:11:02 am »
TiN, I am going to message you about the Keithley 417 PicoAmmeter w/ 4170 input head.
« Last Edit: December 23, 2018, 11:18:14 am by Inverted18650 »
 

Offline TiN

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Re: Measuring nanoamps and below like a Ninja
« Reply #106 on: December 23, 2018, 07:04:30 pm »
Thanks for offer, Inverted18650, but perhaps some other eager amp-nut would like that 417. I already have enough of backlogged projects.  :scared:
YouTube | Chat room | Live-cam | Have documentation to share? Upload here! No size limit, firmware dumps, photos.
 
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Online MasterTech

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Re: Measuring nanoamps and below like a Ninja
« Reply #107 on: December 23, 2018, 07:22:01 pm »
That is a beast, can handle fA like nothing wow, minor teardown at least coming? ::) ::)
 

Offline VintageNut

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Re: Measuring nanoamps and below like a Ninja
« Reply #108 on: January 07, 2019, 05:17:26 am »
I believe that I have shared these resistors on a different thread. For this thread, these resistors are intended to be used with an electrometer to check calibration points.

One end of each resistor has a BNC jack. The jack is for the voltage source of the electrometer. Any leakage from HI to LO through this jack is not measured. So, this jack can be a junk BNC with no negative effect on it intended use.

The other end of the resistor is a 3-lug triax jack. This jack is for the triax jack of the electrometer.

These resistors can also be used with a sourcemeter. Care has to be taken to account for any leakage (if any) associated with the BNC jack.   

I had these calibrated at a primary lab in 2017. I will be taking them back again for a cal in February of this year.

I have no idea about temp dependence of these. That info would be needed for any rigorous cal usage. 
working instruments :Keithley 260,261,2750,7708, 2000 (calibrated), 2015, 236, 237, 238, 147, 220,  Rigol DG1032  PAR Model 128 Lock-In amplifier, Fluke 332A, Gen Res 4107 KVD, 4107D KVD, Fluke 731B X2 (calibrated), Fluke 5450A (calibrated)
 

Offline e61_phil

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Re: Measuring nanoamps and below like a Ninja
« Reply #109 on: January 07, 2019, 06:11:44 am »
Could you say some words about the calibration in the lab? How did they cal these resistors?
 

Offline VintageNut

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Re: Measuring nanoamps and below like a Ninja
« Reply #110 on: January 07, 2019, 09:29:07 am »
Could you say some words about the calibration in the lab? How did they cal these resistors?

I can sketch the methodology, but I do not have total command of the calibration procedure.

It was explained to me that the calibration system is a bridge. The bridge uses a very old collection of Keithley 5155 resistors that have a long calibration history. The bridge also has an old Keithley electrometer. The remainder of the bridge is unknown to me and the exact procedure is also unknown. I will try to find out more details when I visit in February.

Attached are the calibration reports


« Last Edit: January 07, 2019, 09:38:49 am by VintageNut »
working instruments :Keithley 260,261,2750,7708, 2000 (calibrated), 2015, 236, 237, 238, 147, 220,  Rigol DG1032  PAR Model 128 Lock-In amplifier, Fluke 332A, Gen Res 4107 KVD, 4107D KVD, Fluke 731B X2 (calibrated), Fluke 5450A (calibrated)
 
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Offline VintageNut

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Re: Measuring nanoamps and below like a Ninja
« Reply #111 on: January 07, 2019, 09:37:34 am »
I double posted and missed one. Here is the missing one.

working instruments :Keithley 260,261,2750,7708, 2000 (calibrated), 2015, 236, 237, 238, 147, 220,  Rigol DG1032  PAR Model 128 Lock-In amplifier, Fluke 332A, Gen Res 4107 KVD, 4107D KVD, Fluke 731B X2 (calibrated), Fluke 5450A (calibrated)
 

Offline VintageNut

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Re: Measuring nanoamps and below like a Ninja
« Reply #112 on: January 07, 2019, 10:10:59 am »
Since you asked about resistor calibration, attached is a calibration report for my Fluke 5450A. It was calibrated against two Measurements International bridges. The low ohms are calibrated with a constant current bridge and the high ohms are calibrated with a constant voltage bridge. You can see that the 100M resistor in the 5450A is measured with better than 10X uncertainty compared to the 100M stand-alone resistor that I built.

Every measurement on the MI bridge requires a soak time of about 30 minutes. Very time consuming.
working instruments :Keithley 260,261,2750,7708, 2000 (calibrated), 2015, 236, 237, 238, 147, 220,  Rigol DG1032  PAR Model 128 Lock-In amplifier, Fluke 332A, Gen Res 4107 KVD, 4107D KVD, Fluke 731B X2 (calibrated), Fluke 5450A (calibrated)
 

Offline Inverted18650

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Re: Measuring nanoamps and below like a Ninja
« Reply #113 on: January 07, 2019, 08:34:24 pm »
That is a beast, can handle fA like nothing wow, minor teardown at least coming? ::) ::)

We're you asking me or TiN?  :palm:

Online MasterTech

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Re: Measuring nanoamps and below like a Ninja
« Reply #114 on: January 07, 2019, 11:26:47 pm »
That is a beast, can handle fA like nothing wow, minor teardown at least coming? ::) ::)

We're you asking me or TiN?  :palm:
Oh I was asking TiN, that shiny new equipment calls for a teardown
 
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