Electronics > Metrology

Geller voltage reference schematic ??

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Overspeed:
Hello

As Mister Geller is out of business

Does that possible to locate a schematic of the Geller Voltage Reference ? I have a picture from this forum ( linked ) but not the BOM

I dont want to copy just to copy I just want to progress and get new PCB to built some .

Question : As the original is through-holes components I will upgrade with surface mounted when possible

Regards
OS

BU508A:
BOM:

Parts List (from the website):

AD587 chip, e.g. AD587KN DIGIKEY AD587KN-ND (the AD587LN was discontinued), or AD586 series chip for a 5 V board
C062K104K1X5CA MOUSER 80-CK06BX104K
ECQ-V1H104JL Digi-Key P4525-ND
3299W-1-201 MOUSER 652-3299W-1-201 (200 ohms, use 1 k ohms when a wide selection of select and test fixed trim R's are not available)
TRIM R IRC 0.1% MOUSER 66-RC55LF-D-3.24K (for some 587 production runs: only if using a 200 ohm trimmer, 2.87K or 3.01K, see manual)
TRIM R IRC 0.1% MOUSER 66-RC55LF-D-7.32K (see manual)
COPPER LOOPS #18 SOLID COPPER WIRE
2 PIN IDC HEADER
IDC SHORTING PLUG
Mill-Max SOCKT MOUSER 575-193308
solder

Please see attached .pdf for the schematics

Andreas:

--- Quote from: Overspeed on May 23, 2024, 06:50:44 am ---
Question : As the original is through-holes components I will upgrade with surface mounted when possible


--- End quote ---
Dont do that: the wires give a certain decoupling from PCB (and swelling of PCB by humidity)
For the same reason you should use a CERDIP8-Device for the AD587 (e.g. AD587JQ/AD587KQ)
otherwise the drift will be in the range of 0.2-0.5 ppm/% rH.

The SVR(-T) are missing a 100 nF capacitor between the output pins to reduce EMI influences.

The enhanced SVR-T Version from Lars is included in my AD587LW design.

https://www.eevblog.com/forum/metrology/ad587lw-10v-precision-travel-standard/msg1449488/#msg1449488

with best regards

Andreas

HighVoltage:
A few years ago, we had some black edition boards produced.
I might still have a few ...

https://www.eevblog.com/forum/metrology/geller-labs-svr-lars-walenius-black-edition-with-587lq/

Overspeed:
Hello

Thanks for your quick and detailed answer

My idea is to fit the PCB underneath the box cover as carry cot , no wire but studs / through the cover with ring seal / potting ( see picture  as possible other solution  rod are in thread brass so no leak between insulation and wire core ) and use a sealed enclosure with a Nitrogen valve very close to an ATEX enclosure like that

https://www.atexdelvalle.com/fr/coffrets-antideflagrants-atex/junction-boxes

I can make one easy in the right dims as 100 x 75 x 50 or make it easy in 6062 / 5083 alloy or even with a 4 inch square pipe a welded plate and a cover with a quality seal I can also make them from a block of  PEHD plastic

Question : The missing cap 100 nF on the schematic is between 5 and 6 pin ? a ceramic XR7 is enough ?

Regards
OS


 

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