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1V Reference @ 1ppm

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beanflying:
The Acrylic enclosed references uses the AD584KH. It is specced at 15PPM Maximum there is no typical or minimum PPM/C which is a bit strange. Based on what I measured the other warmish day I was getting 1PPM from mine so  :-//

Interestingly the Initial Accuracy is only Maximum rated too  :o

Do a Search for KKMoon or AD584KH reference you should get plenty of hits here on others that have tested it.

spec:

--- Quote from: tggzzz on January 30, 2019, 11:31:40 am ---Folly? No. You'll have fun and learn things. But personally I wouldn't tweak anything based on its output - first attempts are rarely perfect.
--- End quote ---
Yes, well put. I don't actually need to calibrate anything, at the moment. A half-decent voltage reference would just be an interest.
 

--- Quote from: tggzzz on January 30, 2019, 11:31:40 am ---You should understand what's behind the specs for professional high quality meters, especially those related to the drift over time.
--- End quote ---
Oh yes- got that right from the off. I have done quite a bit of precision work, but never designed/built an ultra precision Vref. I spent a year doing the development cal of a precision analog computer at one time, and had access to the highest precision voltage and resistance references, via the company- cost was not an issue. ^-^


--- Quote from: tggzzz on January 30, 2019, 11:31:40 am ---You might like to consider what will/won't happen if you short-circuit your low impedance output.
--- End quote ---
Not much I don't think. But it may introduce a thermal shock to the V Ref Unit, which could take a day or so to recover from.

What does concern me is the secondary effects, like galvanic voltage of metals and solder joints- that kind of thing.

spec:
Perhaps I could outline the V Ref Unit (VRU) design I have been looking at, in the background, recently:

* Ref Voltage: any from 0V to 10V
* Target Absolute Accuracy (max): TBD
* Target Tempco (max): 1ppm/degC
* Calibration: none, or resistor AOT depending on degree of precision required.
* Material Cost (max): $100US
* Development Effort (max): Infinite man hours
* Dimensions (max): Width: 300mm, Depth: 250mm, Height: 150mm
* Weight (max): 1.5 kg
* Case: DIY. Material: TBD, but probably a mixture of plastics and aluminum. The case would have at least four thermally isolated compartments. The first compartment would house the electronics that are primarily responsible for voltage precision. The second compartment would house the components that have a secondary effect on voltage precision, the third compartment would house the precision linear power supplies. The third compartment would have an efficient heatsink. The fourth compartment would house the batteries.
* Power Source: mains and battery. Mains components housed in  wall-wart or similar.
* Power Consumption (max): 100W
* Power Rails: precision low-noise using specialist linear PSU chips
* Primary Voltage Ref: one of the chips that we have discussed
* Buffer to Provide 'zero' Ohm Output Z: super precision opamp (I seem to have found one)
* Thermal Control: Possibly oven controlled primary voltage ref. All relevant circuitry in DIY ovens (simple to do, but the practical side would take some sorting)
The VRU would probably require a six-month burn-in period to reach full performance, but would be usable after a couple of days for less precise work.

Obviously, the VRU would be powered permanently, either from the mains or battery.

Alex Nikitin:

--- Quote from: spec on January 30, 2019, 12:21:55 pm ---Perhaps I could outline the V Ref Unit (VRU) design I have been looking at, in the background, recently:

--- End quote ---

Have a look at this voltage source, manufactured by a forum member here:

http://www.ianjohnston.com/index.php/onlineshop/handheld-precision-digital-voltage-source-v2-detail

Cheers

Alex

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