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Replacing Zener with vreg?
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TERRA Operative:
I'm currently in the process of recreating an unobtanium option board for my HP LCZ meter and I am stuck on one part.

In the top left corner of the schematic below, there is a 6.3V 1%, PD=0.4W, TC=0.001% zener diode.
I'm having trouble sourcing a zener of this type, is it possible that I could stick a vreg here instead?

I think it shhhoouulldd be relatively simple to drop in a vreg set to 6.3V, but I just want to get someone more knowledgeable to make sure there's not a trick hiding in there. :)
Whales:

--- Quote ---TC=0.001%
--- End quote ---

That sounds crazy grade.  0.001% = 1e-5.  Is the opamp it connects to even that good (eg in terms of offset voltage, tempco)?  I don't see any trimmers on the resistors either, so I can't imagine this needing that high of a spec.   

Typo?  I could still be wrong, but I'm suspicious given the schematic has no further info.


Sidenote: there are variable voltage references available.  Cheapest is something like a TL431, but it doesn't meet the above tempco spec :P
TERRA Operative:
Yeah, I was wondering about that... The part is CR1 in the pic below.

The AD7530LN is good for 2ppm of FSR/oC according to the datasheet.

I haven't looked at the TL074CN, but here's the datasheet: http://www.ti.com/lit/ds/symlink/tl074.pdf
iMo:
It could be an 1N828/829 there, for example (0.001-0.0005%/C).
I think any regulator with tempco <50ppm/C will do..
TERRA Operative:

--- Quote from: imo on November 09, 2018, 05:06:09 pm ---It could be an 1N828/829 there, for example (0.001-0.0005%/C).
I think any regulator with tempco <50ppm/C will do..

--- End quote ---

That looks like a 6.2V zener, would that be ok to use instead of a 6.3V?

It looks like the HP part number (1902-0692) cross references to the JEDEC part number DT790107A but I can't find anything on that number online beyond HP cross references.
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