Electronics > Metrology

Measuring nanoamps and below like a Ninja

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I don't have any earth pin into my wall sockets. As many houses.
Therefore i use pack of metals pole which i'm installed several years ago into garden, and thick cable lifted at several floors for connect lab.

Firmware progress:
User interface - still in progress.
Main functionality - expanded with automatic recalculation ramp speed trough saved capacitors into EEPROM, for set current directly in amperes.

About capacitance for create current.

Unfortunately vacuum capacitors shows unacceptable leakage through glass. I've try use metals ring and ring of graphite coating to add guard ring directly on glass, but isn't help.

For large capacitance 10pF, 100pF, 1nF, 10nF, and high value resistors i planned use full sapphire based electrometric relays-switch, witch i'm extracted from U5-11 v.2 soviet amplifier.
It be separate project of programmable electrometic tool for use together with GLIN and [spoiler!]electrometer[spoiler!].
For less 10pF capacitance i use separate capacitors.

Now i work on algorithm of digital compensate leakage and parasitic effects of large capacitors through realtime ramp speed correction.
Hope push commit to GitHub soon and make cool video after complete GLIN firmware.

Amp-porn: The switch (input jack is also sapphire based triax)

Today mining results...
16 pcs sapphire, low charge injection relays Tg5.289.049
16 pcs sapphire small female triax. (2 pcs already used in project)
1 pcs sapphire big male triax.

Leakage each parts is less 100aA at 10V. Typically is ~10-20aA after several hours(up to days) hold at 10V.
But that parts don't liked change of potential, because sapphire rings discharged very slow to aA levels.

That scrap i extract from useless, but very rich V7E-42 external switch.
Unfortunately Fortunately!!! that switch not supported by V7E-42 electrometer, and used as full separate part with some separate external controller(type is unknown, not part of the electrometer kit).
Also build quality of that external switch is low... often air gaps between low quality PCB and relays pin is zero... :palm:
I'm think that switches be made for only one purpose: to be disassembled by next generation of crazy ampnuts  >:D

Note: Tg5.289.049 relays designed for soldering to PCB by 3 of 6 pins (coil and case), 3 electrometrical pin not connected to any PCB traces, they used only for air wiring technique.

Today I caught myself on idea "that it would be good practice to make a Swiss knife from GLIN".
I started integrating the LEA-M8F module to the timebase board for provide time-autocalibration and disciplined oscillator features. And I also started thinking about installing an low INL ADC to "Output board" for self-calibrate INL of DAC and add electrometer functionality to GLIN.

I need to go group therapy urgently!!!! Otherwise it be a second long-long project like as my Ultra-Micron project witch i develop around 4 years....


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