VREF10-001 r9

                     The VREF10-001 r9 has the following updates:

*Operates from internal 9V batteries or external 24VDC power supply

* Output terminals are high quality gold plated 5-way binding posts

*Gold plated circuit board

* Temperature compensation circuitry provides 60ºF to 90ºF ( 16C- 32C) TC of < +- 2uV/F (0.4ppm/C) max (Box Method)

*Easily accessible current limited battery voltage test points

*All Temperature sensitive components (LT1021, etc) are located inside the enclosure to make the Vref10-001 r9 insensitive to ambient air currents

This small (3" x 3"), portable, precision voltage reference can be used to check the calibration of your DVM or DMM. The VREF10-001 r9 features a 10.00000V output, and is conservatively rated to be accurate within 0.001% for a minimum of 8 months. The circuit is based on the Linear Technology LT1021BCN8-10 which uses buried Zener technology resulting in excellent long term stability. Here is a link to the LT1021 datasheet on the Linear Technology website: https://www.analog.com/media/en/technical-documentation/data-sheets/1021fc.pdf

The VREF10-001 r9 can either be powered by the 2 included RayOVac Alkaline 9V batteries or an external 24VDC (24V +-1V recommended) power supply.  When powered by the batteries the unit is completely self contained and easily transported. An on-board on/off switch allows you to maximize battery life when not in use. Current drain is less than 5mA so the batteries will last many 10's of hours. Both the battery and 24V external inputs are reverse polarity protected and can withstand up to +/-40V without damage.

Buried Zener References become more stable the longer they are powered-up.  Operation with an external 24VDC supply allows the VREF10-001 r9 to be continuously powered without draining the batteries.  An optional low cost, UL approved, linear, regulated, 120VAC/60Hz input 24VDC output, power supply is available at our online store.  Alternatively, you can use your own 24VDC supply with a 2.5mm/5.5mm plug.  A lit low current red LED indicates battery operation and a lit orange LED indicates external power.  The switchover from batteries to external supply (or vice -versa) is virtually instantaneous and when both are present priority is given to the external supply.  

Temperature compensation keeps the VREF10-001 r9 temperature coefficient to less than +/- 0.4ppm/C over the range of  60ºF to 90ºF (16C to 32C ).  The temperature stability is verified by using our thermal chamber to slowly change the temperature from  60ºF to 90ºF over a period of 12 hours and measuring the Reference output every 0.1ºF 

 The temperature graph for your particular VREF10-001 r9 is available as an option via our online store. 

After the unit is assembled, it is powered up for a minimum of 2000 hours to "age" the reference and confirm its long term stability. During this aging process, daily measurements are made of the reference output voltage- the LT1021 is replaced on those units that have excessive long term drift. After aging, a trim pot is carefully adjusted so that the output voltage is within 5uv of 10.000000V as measured by our calibrated, 8.5 digit Keysight 3458A DMM. (Keysight Certificate of Calibration WO-00730471, valid through March 8, 2025). The ambient temperature is recorded and unless specified otherwise will be in the range 68 to 70 degrees F. We can perform calibration at other temperatures- please inquire for feasibility and pricing.

For maximum accuracy it is recommended that the reference be powered-up 15 minutes before use and also operated as close as possible to the calibration temperature.

Recalibration is free for the first two years after purchase- just mail it back to us and pay for return shipping.  For destinations within the USA please send a $11.00 PayPal payment to doug@voltagestandard.com. After two years the calibration charge is $15.00 plus shipping.