which component has exponential i-v characteristics down to 1 pA?

OK, don't use that diode!

I'm sure there are many small high-beta BJTs that continue to work well in the pA region, but I haven't taken measurements lately and don't recall right now where to look for some old ones. But I did post on one of my web pages some diode measurements that show good results to 1pA for PAD-1 diodes and 2n4117A gate-source junctions, see

The curves show logarithmic linearity over seven to eight decades.

I should revisit these parts and extend the measurement below 1pA, using my lab's Keithley electrometers, recently-acquired on eBay. One of my instruments, a 642 with remote head, goes down to 100aA.

Just as you would your Engineers, if you were a manager. Make sure to tell them that the company is doing "just great" from time to time.

You might try using an ordinary display LED. I've measured them to have leakages of less than 50 fA over -5V to +0.5 V, so they don't go ohmic near zero bias the way silicon diodes do. Make sure you keep it in the dark!

Cheers,

Phil Hobbs

Thanks for the quick replies

Probably about $50k per year.

snip

Hi Win, I was just wondering how much tech stuff do you/Rowland.org buy off Ebay?

martin

Serious error. All shortcuts have disappeared. Screen. Mind. Both are blank.

"alan" wrote

Hey, we suggest them for everything else: Why not use a PIC?

TIM -> A/D -> PIC -> D/A

Any simulation curve you like ...

• * *

Zeke snipped-for-privacy@zyzzly.net wrote

Use a PIC! Drill a hole in both ends of the PIC and insert into the broken linkage, crimp broken linkage ends to secure.

ROTFLMAO

Cheers Terry