How much Vin was?

I set the voltage at 10 V, so 1 GΩ would give me 10 mV out of the divider, 10 GΩ gave 1 mV, 100 GΩ gave 100 μV, and so forth.

 

Wow, 2TΩ!! All secured to a two mundane (are they?) crocs?? And then the sandapaper... Not a game I could expect to play in this life, it seems.

Having set up a I-V tester vs temperature (-80 to 200 C) system to activation energy of semiconductors, it's just a real pain. For really high values of resistance, I'd set the electrometer to Coulombs mode and Zero it somewhere after switching modes for some measurements and count coulombs for 60 seconds and divide by 60. 2 pA at 100 V was a relatively stable number. e.g. R=100V/2e-12A

The meter did have a resolution of 0.1 fA in amps mode (Keithley 617: https://www.bing.com/search?q=keith...=-1&sk=&cvid=A113F469AA6D48B79521D1491A2C23DD, but the fixturing wasn't stable enough.

You could tell when a piece of glass was clean....

There were a few issues, like how to clean a piece of glass. We used Acetone,
https://en.wikipedia.org/wiki/Trichloroethylene, followed by dip in Trichloroethane (Freon TF) and blow dried with Argon. Dunno what the replacement was for Freon TF,

See: http://www.besttechnologyinc.com/pr...-phase-out-and-replacement-with-3m-novec-hfe/

A vapor degreaser was used for larger batches.

One etching process wasn't clean enough. It left photo-resist residue that could only be removed by Benzene. We quickly got rid of that stuff.

It's interesting to put two probes on a piece of paper and measure the resistance based on humidity or, for that matter, a piece of glass.

The environmental chamber had two issues: Vibration. The triboelectric effect comes into play. Something moving in the Earth's magnetic field. The internal fan caused wire movement. We didn't get humidity control, so purging with Dry Nitrogen sometimes had to be done,

 

BTW, could you mention one or two components (are there some?) measuring some GΩ?

Please see page #13 of the PDF linked in post #32 on this thread for an application example of a 220GΩ 'lumped resistance' -- again, I will endeavor to upload a photographic image of said component this afternoon/evening

FWIW Such large resistors (in my experience up to 1.2 TΩ) are in common use in ionization chamber instrumentation...

It is worthy of note that a significant advantage of the Alphalab instrument (and its ilk) is to be appreciated in its low (applied) EMF operation - which being an important consideration with many components/materials.

Best regards
HP

PS
Disclaimer -- Aside from my 'status' as a 'satisfied customer' -- I have no connection (NPI) whatever with "Alphalab" - nor is it my intent to act as a 'shill' therefor!

 

As per 'no better time than the present...' -- Pictured below is a brace of 220GΩ resistors ('liberated' from VDC-715s) -- although 'speced' at 20% tolerance, 10% is the rule and 5% common!

Best regards
HP

 

Wow... I've rarely seen a thread go so far on so little.

 

Wow... I've rarely seen a thread go so far on so little.

What can we say? -- To render the (well neigh) late Radio Shack --- You've got questions - we've got answers!

TTFN
HP

 

Here are some samples from my Gigaohm resistor collection.




The top resistor is 1000GΩ.
The bottom one is 100GΩ.
We use resistors above 1GΩ in cryostat chilled (liquid N2) charge-coupled FET-input preamps for semiconductor gamma-ray detectors, Ge(Li) and hyper-pure Ge detectors.

The resistors are used in two places, at the high voltage bias on the detector and the feed-back loop from the output of the preamp back to the gate of the FET.

Gigaohm resistors are measured with a Wheatstone Bridge. We have a 1960 General Radio GR 544-B Megohm bridge.



Here is a photo of one on ebay.

 

Where does one get a 100GΩ resistor?

Cur the circuit open.