Voltage Calibrator

Discussion in 'General Electronics Chat' started by Dr.killjoy, Dec 13, 2015.

  1. Dr.killjoy

    Thread Starter Well-Known Member

    Apr 28, 2013
    1,190
    156
    The other day I dropped my meter and it started to act weird but after a tear down for a check up it's fine again..
    So I been working on a simple and hopefully cheap voltage reference in order to check you meter.. Is it better to use a tighter tolerance and larger ppm temp or larger tolerance and smaller ppm temp on Ref chips ??? Would you use a battery or a wallwart to power it ??¿ I was looking to use a main power switch and auto power circuit for testing..
    Would you guys be interested in posting a vague prototype??


    Thanks
     
  2. Picbuster

    Member

    Dec 2, 2013
    376
    50
    buy a voltage reference scan internet for price, specs and connection methode.
    ppm temp not important if you want to go cheap. but 3 decimals is possible.
     
  3. joeyd999

    AAC Fanatic!

    Jun 6, 2011
    2,693
    2,765
    You must define your error budget across an acceptable operating temperature range. Then, insure both basic accuracy and PPM fall within that budget.
     
  4. AnalogKid

    Distinguished Member

    Aug 1, 2013
    4,546
    1,252
    Interesting tradeoff, and totally dependent on both the application and the location of the finished reference. My basement workroom has no direct sunlight (its a basement) so it is the closest thing to a constant temperature environment year-round. This argues for the good accuracy / bad tempco option. But if the reference is sitting under the forced air duct into the room, then the temperature could change 30 degrees in 1 minute. Location, location, location...and error budget.

    ak
     
  5. Dr.killjoy

    Thread Starter Well-Known Member

    Apr 28, 2013
    1,190
    156
    I was looking to use a maxiam chip at 2.048v with .02% tolerance and 5ppm temp.. You can get better tolerance with a calibrated high count meter which I don't have but might include if interest show..I chose to use the 2.048 ref cause it would show the max resolution of all my meters..
     
  6. MrAl

    Well-Known Member

    Jun 17, 2014
    2,442
    492
    Hi,

    It might be better to go with the highest voltage you can get because you can always divide it down to a lower voltage using methods similar to ancient geometry techniques.

    For example, if you get a reference that is 4.096v then you can divide that in half using two equal resistors down to 2.048v, and you can get that pretty accurate because you can match the resistors yourself. This way you have at least two accurate voltages already.
     
  7. dl324

    Distinguished Member

    Mar 30, 2015
    3,250
    626
    Calibration is performed on all ranges. For some ranges, it will be near full scale; for some, it won't. So a single calibrated voltage reference isn't that useful. I saw some 10.000V (maybe 4 significant digits) reference being sold, but what use is it? A meter with 3 1/2 digits needs something like 0.190, 1.90, 19.00, etc. If you use a higher voltage reference with voltage dividers, accuracy depends on the precision of the resistors.

    Can your meter(s) even be calibrated on every range? Most of the inexpensive ones are throwaways.

    Will you be taking measurements that require high precision?
     
  8. Dr.killjoy

    Thread Starter Well-Known Member

    Apr 28, 2013
    1,190
    156
    The point of using 2.048v means that almost meter should show full scale even in a 3.5 digit meter. My meters are auto ranging so a single voltage reference is good enough seeing how the meter uses a single trim pit to calibrate the meter..The point of this is to check the accuracy of your meter not to calibrate unless you want too..
    I am using a already calibrate reference to check the meters vs building a reference that needs to be calibrated.. Unless you want to modify the design for better tolerance..
     
  9. GopherT

    AAC Fanatic!

    Nov 23, 2012
    6,073
    3,856
    Just find a friend with a calibrated meter, measure the voltage of a battery. Bring the battery home and calibrate your meter as needed. I doubt a meter with 3 digits will be off by much over time. My 3 meters are all within a mV of each other after 10 years.
     
    Dr.killjoy likes this.
  10. Dr.killjoy

    Thread Starter Well-Known Member

    Apr 28, 2013
    1,190
    156
    Thanks for Idea...
    But the end result is for fun and a voltage reference for under $20 hopefully.. The ride itself is going to cost that in gas for me ...
     
  11. Techno Tronix

    Member

    Jan 10, 2015
    140
    10
    Calibration software is available to automate all or part of many calibration processes, manage calibration and asset data, and perform other useful tasks as well. 5080/CAL is easy-to-use calibration software for the 5080A Multi-Product Calibrator.
     
Loading...