V7-45 electrometer made in Belarus (welcome in attoamps world)

[drghl]

...
No problem, see here:
http://offtop.ru/dustyattic/v20_686383_8.php
Page 25

I loaded the document down. These are 190+ pages of a manual. Plenty of stuff to read and I am slow. The last time Iwas reading russian texts is 40 years ago. Will take some time. Thanks for the link.

[bsw_m]

...
No problem, see here:
http://offtop.ru/dustyattic/v20_686383_8.php
Page 25

I loaded the document down. These are 190+ pages of a manual. Plenty of stuff to read and I am slow. The last time Iwas reading russian texts is 40 years ago. Will take some time. Thanks for the link.

So, if You have big interest, You may fun by read manual and schematics diagrams for predecessor of V7-45.
This metter is V7-29 which was developed in 1976. https://yadi.sk/d/y5kjpVAvJyrNkQ (sorry for poor quality for this manual).
This device comparable to V7-45 in sensitivity, but had an upper range of 1E-13A
This device is digital, but build on logic, and don't have GPIB.

[drghl]

...
Earlier  i'm say here: "Atto-amps - good chance to start learn Russian. It's very exciting!"
It's true 

Russian is the 4th of the most common languages in Europe. In Germany there live around 3 million Russian speakers. In my village maybe 300.
I volunteered in Russian classes in Gymnasium (High school) because my parents spoke Checkish and Polish fluently (refugees from Checkoslovakia) but I decided to rather study the language of the "big brother". With a background in Latin the Russian systematics was not a challenge. However to find a native language speaker for conversation practicing was impossible. During a trip to Berlin I tried to chat with a Russian soldier who was standing there not far from the "Brandenburger Tor" but he refused to talk to me. Later during trips to Japan with Aeroflot I had the opportunity to talk to plane and hotel personnel but they were quite repelling, maybe because I belonged to the class enemy. Cold war was dominating the scenery.
Today, it is much easier because the civil society no longer experiences the pressure of politics, which is good. Nontheless my Russian knowledge got very rusty and I am now enjoying freshing it up.

[bsw_m]

Some upgrade and tuning for my V7-45.
First, i'm replaced the S5-50 100Meg 0.1% resistor, that out of spec (+0.29%) in electrometric module to precision microwire resistor MRH 100Meg tolerance 0.1%
In fact they have resistance 100Meg -0.04%, I'm compensate this with S2-29V in series resistor 42KOhm.
As result, TIA ranges (1E-7 and 1E-9) tight aligned. And also tight aligned higher bands for integrator. Where this resistor using to calibrate integrating capacitors.
TIA ranges check:

Higher integrating range check:


Second. Where I'm restored with a complete disassembly and assembly the dynamic resonance capacitor DRK-6. The integration capacitor which is installed on it was changed their capacitance, and meter need calibrate this capacitance. The calibration of this capacitor is carried out by the method of supplying a charge 1E-10C and setting the switches in the instrument. For supply a charge I used differentiator from my NK4-1.
As a result, checking with the NK4-1 lower ranges wich using this capacitor showed full compliance with the specification with a good margin.

Lower integrating ranges check:


And last point check, where readings should correspond to 20 ±8 lsb.


Third.
As you can see, my instrument has been replaced with a new backlit display. The display was purchased from the Display Unitary Enterprise.
But backlit module is DIY. To build backlit module I'm use the light guide and leds from cracked "slim" notebook display.
DIY backlit module with new display

For powering this backlit module I'm build the voltage multiplier and constant current drive based on jfet. That mounted on outguard powersupply board.


Now the project for the modification and study of this wonderful instrument can be considered closed and I started work on the next interesting project. Soon I will start publishing results on it.
(Spoiler: this is very hard restoration projects for V7-57/1 and V7-57/2 electrometers)

[bsw_m]

A small modification of the external measuring block was made. The Zener diode was replaced with a more stable one in the offset compensation circuit DRK-6. Modification result:

[Kleinstein]

That is a huge difference for a relatively small change.

I don't think the very short time (well less than instrument time constant) part is really relevant. The "stability" is more the instrument rol off and not real.

[justanothername]

At the time of the article, I believe the most popular mechanically vibrating capacitor units on the American market were the Cary "vibrating reed" electrometers.  Here is an advertisement for a later version of the Cary unit

Attached is an advertisement of a TR-84 from Takeda Riken.

Today I've read the article from Shodan about the V7-45:
https://ampnuts-com.translate.goog/v7-45/?_x_tr_sl=auto&_x_tr_tl=en&_x_tr_hl=de&_x_tr_pto=nui
... really impressive.

[serg-el]

More complete description of the electrometer

[serg-el]

The 1991 catalog also contains a description of the TR8411, and its accessories and theory of operation.

https://cloud.mail.ru/public/cHj8/KqkYY6W9g
A high resolution ,1000 MB !!!
https://cloud.mail.ru/public/gWqE/sUf6LTmqt

[Vtile]

Correct me if I'm wrong, but isn't all separation actions creating a charge injection or at least charge fluctuation. As the charge field reforms again from mono to binary structure? Edit. As Interfacial phenomena in boundary double layer.

Are those step like smaller jumps (e.g. 0.8 hours in the 1st log) the errors from the auto zero ?
I would expect the Auto zero and also the integrator reset to use mechanical contacts of some kind. There is a chance to have some contact problems, especially if not used much for a long time. Even with mechanical switches there could be some kind of charge injection when opening the switch. Details one when and where the contact opens can make a difference and thus cause some instability.

Impurities / radioactive decay could be an issue, but why boron ? It is usually heavy isotopes that show alpha decay, like impurities in the solder or maybe radon gas.

[Vtile]

I must say that that DRK-6 flux capacitor is fascinating piece of engineering.

[Kleinstein]

Correct me if I'm wrong, but isn't all separation actions creating a charge injection or at least charge fluctuation. As the charge field reforms again from mono to binary structure? Edit. As Interfacial phenomena in boundary double layer.

Are those step like smaller jumps (e.g. 0.8 hours in the 1st log) the errors from the auto zero ?
I would expect the Auto zero and also the integrator reset to use mechanical contacts of some kind. There is a chance to have some contact problems, especially if not used much for a long time. Even with mechanical switches there could be some kind of charge injection when opening the switch. Details one when and where the contact opens can make a difference and thus cause some instability.

Impurities / radioactive decay could be an issue, but why boron ? It is usually heavy isotopes that show alpha decay, like impurities in the solder or maybe radon gas.

The is some charge fluctuation apon switching. One would have at least the so capped reset noise of sqrt(kTC). With the integrator the switching is not not done very often, especially at low current. With metallic parts there should be not much additional fluctuations.