Any interest in a low priced laboratory grade voltage reference? - Page 1
Forum section: electronics / projects

author: captbilly
author_rank: Newbie
timestamp: December 10, 2013, 12:18:59 am
content: The company I work for is developing a very high resolution DAQC system. Each board requires an extensive calibration at many different voltages, sample rates and temperatures, so that it can deliver the performance we are looking for (similar to the Agilent 34980A specs). We were not able to find a calibration source, at anything like the price we were willing to pay, that could output the multitude of simultaneous voltages we needed so we started developing our own in house solution over the past year. In the process we started thinking about developing a commercial voltage reference/transfer standard that would slot in between the venerable Fluke 732A, and the many low cost solutions. Is there any interest in a reasonable cost (say <$500) temperature stabilized voltage reference/transfer standard?I am not suggesting that we can build something as stable as the Fluke 732A for less than 1/10th the cost. What we are contemplating is a 1000 hr burned in, fully low temperature stabilized (including during shipping to the end user) NIST traceable reference. Specs look like well under 1ppm short term, a few PPM/sqrt month long term drift, nearly zero temperature drift (way under 1 ppm), no temperature hysteresis (since the temperature never changes on any of the critical components). We are also thinking that for many/most users the old 10 volt and high impedance 1.018 volt references on these standards is not all that useful. We would instead offer voltages in the 1-5 volt range (any thoughts on exactly what voltages would be most useful), and possibly custom voltages as an option.The basic reference is one or more buried zener references in metal cans or floating ceramic packages, burned in for 1000hrs then calibrated. We would use 1ppm or better foil resistors, battery backup for temperature control and power during shipping and power failures, in cal light (lets the user know if temperature limits were exceeded or if power was lost). The entire precision section will be hermetically seal in an actively heated and cooled to keep both temperature and long term drift to a minimum. Outputs would be pure copper (maybe tellurium copper) low EMF, as would the leads. What are your thoughts on what kind of market there may be for such a product?I am the lead guy on this project and I am looking at presenting the idea to the rest of managment. I am certain that they would not have agreed to devote the necessary resources to designing this product, had it not been for the fact that we already had to do the R&D for our own use. We already built a few of these references , with 5, 2.5, 1.25, 0.625, 0.312, 0.15625 and 0.078125volt outputs, and the results have been extraordinary. On our 7.5 digit meters, after the burn in, we see essentially no meaningful change in output over time or temperature (1 count change up and down).

author: EEVblog
author_rank: Unknown
timestamp: December 10, 2013, 12:25:52 am
content: Would be interesting to know how many of these have been sold:http://www.voltagestandard.com/New_Products.htmlPerhaps Martin Lorton can check his serial number?, as he seems to number his references sequentially based on build volume.

author: Galaxyrise
author_rank: Frequent Contributor
timestamp: December 10, 2013, 05:38:41 am
content: Have you readhttps://www.eevblog.com/forum/projects/ultra-precision-reference-ltz1000/? That reference has an order of magnitude better long-term stability than the specs you described.Most of my gear has been $200-$250; I don't know if I can really budget $500 for a toy in my little hobby lab. But what you're describing sounds a lot nicer than what I'd expect at the $250 price point!I would like a really stable 10V though, and am getting pretty tempted to follow in the footsteps of those in the linked thread. I want 10V because that's a common calibration voltage. I can probably double a 5 for that, though.

author: orin
author_rank: Frequent Contributor
timestamp: December 10, 2013, 06:11:37 am
content: Quote from: Galaxyrise on December 10, 2013, 05:38:41 amI agree on 10V. The cal cert for my Agilent 34461A lists 0.1V, 1V, 10V, -10V, -100V and 1000V."10V" isn't "old" IMO.

author: Dr. Frank
author_rank: Super Contributor
timestamp: December 10, 2013, 10:08:20 am
content: Perhaps you are not aware about, but from your description, you need at least 2 precision devices:1st: An ultrastable volt reference (e.g. of random output voltage)2nd: An ultraprecise Transfer Standard.Working examples for relatively cheap reference designs can be found on the LTZ thread, i.e. 7.1..... V output, stable to < 1ppm/yr, < 01.ppm/K, and for the transfer standard: Fluke 720A or in combination, a HP3458A.It's very difficult to build such a transfer standard on your own, and additional cheaply.Only if you own such a transfer standard, it's possible to build fixed reference outputs (dividers) by precision resistors at low cost, but you have to routinely recalibrate them.Frank

author: lau190
author_rank: Newbie
timestamp: April 11, 2014, 12:06:26 am
content: I have two DIY 263 10V reference ,both have <3ppm/year,I bought it from 38hot forum member at $2xx each.