ultra low current measurement

Hi,

i´m looking for a circuit (shematic) for current measurement in a range from

Thanks Udo

Udo Beckmann schrieb:

Hi Udo,

first read the following about femtoampere stuff:

Jorgen

Right, that was a figure of speech, not a literal instruction.

"Arie de Muynck" wrote

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

For glass optics 99% (or whatever you can get your hands on) isopropyl alcohol is the usual 'final rinse'.

What do Caddok's application engineers recommend?

NO! Don't ever touch them with your bare hands! ;-)

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

-- Regards, Arie de Muynck

problems

acid

Whatever you do, don't use sulfuric acid instead of nitric!!

Norm Strong

I read in sci.electronics.design that normanstrong wrote (in ) about 'ultra low current measurement', on Fri, 10 Dec 2004:

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.

problems

I do not think electronic components appreciate nitric acid.

Wim

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.

Finger nail solvent has oils added to the acetone.

Sure you can. Acetone can be obtained by quart or gallon at most hardware stores.

Actually, for general cleanup, I prefer denatured alcohol... acetone may eat the components.

...Jim Thompson

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.

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

But the Q-tip would add (possibly undesirable) organics. I would then give them one or two rinses using new (and rinsed) plastic containers similar to tupperware (cheap as all heck, 6 or more per retail box depending on size). Lift out by lead and let air dry for 4 hours or more.