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The SVR Series 
SVR A basic 10V board supporting a monolithic Analog Devices AD587LN or a AD587LQ (ceramic package) voltage reference
chip with a trim circuit for calibration as a transfer reference. Short term transfer accuracy: better than +/- .0005% absolute (+/- 5 ppm), guaranteed to remain longer term (6 months) within +/- 500 uV (+/- .005%) of absolute as rated 1. {5 ppm / ºC} $39.95 (AD587LQ CERDIP)
Since first offered in 2004, many hundreds of SVR boards are now in use world wide.
SVR boards can ship in the US by USPS First Class Mail for $2.57 or Priority Mail for $5.35. International buyers please contact us or check USPS prices for 5 ounces (oz), SVR shipping box is 7"x 5" x 4".
Short term transfer accuracy applies in the short term at the reported temperature and at the specified power supply voltage (15.0V for 10V SVR references) after of warm up period of 30 to 60 minutes, <10 ppm within 5 minutes.
The SVR requires an external (not supplied) single 15 VDC power supply, preferably using a linear regulator. With no load on the SVR board, the board draws on the order of 2 mA. A 15 VDC linear power supply rated at 80 milliamps or more is recommended. For relatively low accuracy applications (.01%), two 9V batteries in series can power the board at about 18 V.2
SVR bare printed circuit board with no components: $7.95
SVR (boards only) are now RoHS compliant, and can sell again to EU countries.
SVR Specifications:
Temperature Coefficient "L" grade: 5 ppm / ºC
Short term transfer accuracy: better than +/- .0005% absolute (+/- 5 ppm).
Short term transfer accuracy applies in the short term at the reported temperature and at the specified power supply voltage (15.0V for 10V SVR references) after of warm up period of 30 to 60 minutes, <10 ppm within 5 minutes.
All reference boards and boxes are calibrated to within +/- 10 uV absolute and guaranteed to remain longer term (6 months) within +/- 500 uV (+/- .005%) of absolute as rated.
Extra trim resistors are added to narrow the trim range for easier calibration. Calibration data is reported to 10 uV resolution (.0001%).
We try to be very clear about what this project is about. We are attempting to provide a low cost absolute voltage calibration point targeted to the amateur scientist, electronics hobbyists, consultants, and schools. Our SVR product is a high quality platform for the AD587 family (in our opinion) some of the best voltage reference chips ever made.
We call the SVR board a "transfer reference". The SVR board is a high quality platform for a monolithic reference chip, nothing more.
Our Fluke 732B, even with its FLUKE NIST traceable calibration, in the art of metrology, is generally referred to as a "transfer standard".
The SVR board is intended to give a small lab a way to verify their 10 V calibration point to better than 10 ppm (100 uV absolute). Our field tests have done considerably better, however 10 ppm is our conservative spec. Since the SVR board is rated at 5 ppm/c, the board should be used at about the same temperature as we calibrated the board (as reported) after a warm-up period and at about 15V. The reference chips we use are rated at 100 uV / V (power supply), however most perform much better.
The specifications are, for all practical purposes, the specs of the chip itself, and is not degraded below spec by our precision trim circuit which uses high quality IRC 0.1% 20 ppm/c trim resistors (the 20 ppm/c is per resistor, not tracking, and it is of the trim range, thus not deteriorating the board 5 ppm/c rating, and the 100 ppm/c trimmer is a small fraction of the IRC trim Rs). The boards are burned in for 200+ hours before final calibration. Final calibration is done with our Agilent 3458A (new in 2005) referenced to the 732B. (A "calibrated" hp or Agilent 3458A -alone- is no longer sufficient at 10 ppm absolute and below.)
The details of high precision use, 30 to 60 minute warm-up, use as close the temperature where we did the calibration, power supply voltage of 15V +/- 0.1V are all just to squeak the last ppms possible (to get as close as possible to our 732B voltage) using this relatively inexpensive method. At relatively low precision (e.g. 0.01%), these are all non-issues.
The AD587 series reference chips are rated at 15 ppm / 1,000 hours of operation. Very close inspection of most monolithic reference chip family specification sheets reveals a 1,000 hour rating generally ranging from 10 to 60 ppm / 1,000 hours.
All checks and money orders should be made payable to "GELLER". Please see our ordering page for more information.
Our Low Cost Voltage Transfer Project for Amateur Scientists, Electronics Hobbyists, and Schools, is Supported in Part by Analog Devices Incorporated. Please visit the Analog Devices website!
1 By maintaining a calibrated Fluke 732B transfer standard in conjunction with our 2005 Agilent 3458A DMM we are able to offer NIST traceable references at affordable prices. Our 732B is under a Fluke calibration contract.
2 Suitable Power Supplies: Inexpensive linear "open frame" supplies can be used. For example, 15 VDC models rated at 0.4A, 0.8A, 1A, and 1.5A are generally available at surplus and auction sites. Remember to add an AC power fuse when using open frame supplies and for those less experienced, please observe standard line voltage safety practices (e.g. cover exposed AC line connections).
COPYRIGHT © 2005 JOSEPH M. GELLER