ultra low current measurement

U

Udo Beckmann

Guest
Hi,

i´m looking for a circuit (shematic) for current measurement in a range from
0,1pA to 100pA.

Thanks
Udo
 
Udo Beckmann schrieb:
Hi,

i´m looking for a circuit (shematic) for current measurement in a range from
0,1pA to 100pA.

Thanks
Udo
Hi Udo,

first read the following about femtoampere stuff:

http://www.national.com/rap/Story/0,1562,5,00.html

Jorgen
 
Jorgen Lund-Nielsen wrote...
Udo Beckmann schrieb:

I'm looking for a circuit (shematic) for current measurement
in a range from 0,1pA to 100pA.

first read the following about femtoampere stuff:
http://www.national.com/rap/Story/0,1562,5,00.html
And start getting your hands on a high-value resistor, say
10G-ohms (for 1V drop at 100pA), etc. Farnell stocks them.


--
Thanks,
- Win
 
Arie de Muynck wrote...
Winfield Hill ...
Jorgen Lund-Nielsen wrote...
Udo Beckmann schrieb:

I'm looking for a circuit (shematic) for current
measurement in a range from 0,1pA to 100pA.

first read the following about femtoampere stuff:
http://www.national.com/rap/Story/0,1562,5,00.html

And start getting your hands on a high-value resistor, say
10G-ohms (for 1V drop at 100pA), etc. Farnell stocks them.

NO! Don't ever touch them with your bare hands! ;-)
Right, that was a figure of speech, not a literal instruction.


--
Thanks,
- Win
 
I read in sci.electronics.design that normanstrong
<normanstrong@comcast.net> wrote (in <e7nud.740307$8_6.127082@attbi_s04>
) about 'ultra low current measurement', on Fri, 10 Dec 2004:

Whatever you do, don't use sulfuric acid instead of nitric!!
I don't remember anything dire about that, from my chemistry lessons 50
years ago. In fact, IIRC, we made chlorine with KMnO4, H2SO4 and NaCl.
No doubt that's not allowed now.

There were few things we weren't allowed. White phosphorus and arsenic
compounds, I think.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
BTW, what is the best method to clean these things? I've had some
problems
cleaning 100G resistors (Caddok, AFAIK).

For cleaning laboratory glassware the standard is a mix of nitric acid
and potassium permanganate. Search w/ google for more info.

I do not think electronic components appreciate nitric acid.

Wim
 
Wim Ton wrote...
BTW, what is the best method to clean these things? I've had
some problems cleaning 100G resistors (Caddok, AFAIK).
All my gig-ohm resistors have glass housings. I imagine they
clean nicely with alcohol, if needed (which I haven't). If you
are especially worried, try acetone, which if memory serves, can
be picked up as fingernail-polish solvent. Apply with a Q-tip.


--
Thanks,
- Win
 
All my gig-ohm resistors have glass housings. I imagine they
clean nicely with alcohol, if needed (which I haven't). If you
are especially worried, try acetone, which if memory serves, can
be picked up as fingernail-polish solvent.
Lots of impurities though, it might leave more than it took off...

It's too bad these days, you can't seem to buy any real chemicals anymore.
 
I read in sci.electronics.design that Rich Grise <rich@example.net>
wrote (in <pan.2004.12.11.20.33.09.366821@example.net>) about 'ultra low
current measurement', on Sat, 11 Dec 2004:
Sometimes you can also
get toluene, which is the stuff in airplane glue that gets you high. Or
was, before they found out that it was fun, and banned it.
It's a solvent for contact adhesive.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
On 11 Dec 2004 05:57:51 -0800, Winfield Hill
<hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:

Wim Ton wrote...

BTW, what is the best method to clean these things? I've had
some problems cleaning 100G resistors (Caddok, AFAIK).

All my gig-ohm resistors have glass housings.
Well in that case, don't use hydrofluoric acid!! ;->
--

"What is now proved was once only imagin'd." - William Blake, 1793.
 
On Sun, 12 Dec 2004 01:16:40 +0000, Paul Burridge <pb@notthisbit.osiris1.co.uk>
wrote:

All my gig-ohm resistors have glass housings.

Well in that case, don't use hydrofluoric acid!! ;-
Nah. That just makes frosted GOhm resistors. Very chichi, you know.

But one should use them so as to keep them from throwing rocks, as we all know
what happens to those in glass houses.

Jon
 

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