V7E-42 - 16 channels electrometry source-meter - Page 1
Forum section: electronics / general

author: shodan@micron
author_rank: Contributor
timestamp: November 02, 2020, 09:08:40 am
content: void

author: MegaVolt
author_rank: Frequent Contributor
timestamp: November 11, 2020, 02:06:57 pm
content: Should we wait for a teardown?

author: chekhov
author_rank: Regular Contributor
timestamp: November 11, 2020, 02:12:28 pm
content: Quote from: shodan@micron on November 11, 2020, 01:24:36 amSadly this seller does not have В7-45 anymore ...Btw, these triaxials on switch module also sapphire-based ?

author: chekhov
author_rank: Regular Contributor
timestamp: November 11, 2020, 02:59:35 pm
content: This switch does not seem to be a part of ZIP for this instrument, doesn't it ? If so, does it have it's own name ?

author: bsw_m
author_rank: Frequent Contributor
timestamp: November 21, 2020, 12:46:33 am
content: Quote from: shodan@micron on November 20, 2020, 06:20:19 pmWonderful!This confirms my assumption that it will work well. Since I keep track of the continuity of solutions in this device and the earlier microprocessor-based DMM V7-39.Moreover, continuity not only in the digital part, but also in the analog part (ADC, scaling amplifier).

author: khach
author_rank: Contributor
timestamp: November 23, 2020, 01:08:49 pm
content: Any information about electrometric MOSFET pair in HT002 hydride? What crystals used in it?

author: eliocor
author_rank: Unknown
timestamp: November 23, 2020, 01:25:56 pm
content: Quote from: shodan@micron on November 23, 2020, 10:16:24 amJust for curiosity, is there any way to get an higher resolution picture of the hybrid?. TIA_ Elio.

author: bsw_m
author_rank: Frequent Contributor
timestamp: November 24, 2020, 04:36:26 am
content: NT002(NT003) Electrometric mosfet pair designed (R&D) by Dvornikov Oleg Vladimirovich. (MNIPI)https://orcid.org/0000-0002-6632-429XNT002 mosfet pair also used in electrometric amplifier U5-11

author: Kleinstein
author_rank: Super Contributor
timestamp: November 24, 2020, 02:01:16 pm
content: It looks like there is quantization visible, like 0.1 fA steps.

author: Kleinstein
author_rank: Super Contributor
timestamp: November 26, 2020, 08:48:23 am
content: The last end (e.g. factor 3-10 in the time scale) of the Allan variance curve is usually rather uncertain, as there is naturally not enough time to do much averaging over such long time spacings. If the measurement is repeated one could get quite different values there.Still the stability looks quite good though not much different from the one before.Having the maximum at some 15 seconds is odd. What is happening at this time scale ? Is there something like a beat frequency with mains hum, or is here some kind of digital filtering going on for the shorter times ? The zero / reset cycle is considerably longer, more like 1000 seconds.

author: chuckb
author_rank: Frequent Contributor
timestamp: November 27, 2020, 05:07:20 am
content: Thanks for all the pictures and details about these wonderful instruments!I have used Stable32 with 500k sample data sets without a problem. It just takes 10-20 sec to compute the AD. One time I tried to process a 1,000,000 sample file. The software crashed. This was with a workstation PC.Good luck!

author: Kleinstein
author_rank: Super Contributor
timestamp: January 08, 2021, 11:44:34 am
content: I don't think one would really need a TCXO : there would not be sub ppm stability anyway.The low pass filter may mave to be lower cross over, so that there is more averating over the steps from the DAC. 1/10 second would be only some 100 LSB steps (for 20 min cycle). I doubt one would need a faster reaction so the filter would likely be better more at some 1 Hz - still a parameter to trim for the final version.The gain stage from 2.5 V to 20 V would not need to be super stable - just avoid extra crurrent noise from the resistos. One may still consider a different reference, possibly with lower noise, though higher long time drift. This may be as crazy as a 18 V battery stack. One point one does not want is something like popcorn noise.With a giid timing resolution from the µC one may not really need the DDS generator for the clock. Some of the STM32 µCs offer PWM with very fine time resolution (sub ns range), that could be used instead.