2.048v Voltage Reference..

Discussion in 'The Projects Forum' started by Dr.killjoy, Apr 19, 2016.

  1. Dr.killjoy

    Thread Starter Well-Known Member

    Apr 28, 2013
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    I have been working on building a single 2.048v reference in order to check calibration of my meter and other equipment..I choose to use the Maxim Max6126 which is 2.048v and 0.02% tolerance with 5ppm Temperature Coefficient..The reason I chose to use this voltage because it will show full value on all my DMM and should work for most people ...I will be working the design and schematic in diptrace.. The design is not done or even built yet but I am working on finally details in order for me to buy the parts and test and it should be really nice IMO..The unit will powered with a single 18650 cell with a cheap ebay usb charger and battery protection circuit .. I was going to use a normal switch to turn the unit on but will go with a monetary switch circuit I think..My only problem is whether to use all smd parts or use smd and through hole ?? I was thinking all smd since I don't a drill press and I can get away with drilling a couple holes by hand but not set on the idea yet..

    Any comments or suggestions ???
    Hopefully I will be posting a full schematic..

    Here is where I am pulling the circuit from and will be modding it to suit me



    Chip schematic
    Attached below
     
  2. dannyf

    Well-Known Member

    Sep 13, 2015
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    I hink whteve flats yur bat wil be ine wth us.
     
  3. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    My projects all seem to work and my favorite meter, a Fluke 8025A - made in 1983, has not been calibrated since 1985. Seems like an interesting project though.
     
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  4. #12

    Expert

    Nov 30, 2010
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    You must be younger than I. The idea of soldering a dozen SMDs makes my eyes hurt.:(
     
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  5. crutschow

    Expert

    Mar 14, 2008
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    My multimeters only go to 1.999V on the 2V scale.
    What do yours go to?
     
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  6. RichardO

    Well-Known Member

    May 4, 2013
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    My meter is even older. A Data Precision 4 1/2 digit one from when 4 1/2 digits was still special. I have thought about doing similar project but cant find a reference that has 4 1/2 digits of absolute accuracy right out of the package. :-( (I realize that my meter is no where near 4 1/2 digits of accuracy but I can dream can't I).

    Mine, too. Maybe 2 each 1.0000 volt references in series? Analog devices has a ADR130. Not as good as the 2.048 volt references, though.

    Another option would be a calibration resister in series with the 2.048 volt output of the reference. Just big enough to divide with the meter's 10 megohm input to give 2.0000 volts. On second thought, that resistor would be huge since it would have to drop the voltage by about 2.4%.
     
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  7. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    um.. your smartphone is on the fritz.. Or turn the autocorrect back on..
     
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  8. #12

    Expert

    Nov 30, 2010
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    My Fluke counts to 3200...and sometimes just a tiny bit more.
     
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  9. tcmtech

    Distinguished Member

    Nov 4, 2013
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    I say cut holes in your PCB and recess mount the surface mount stuff down in them that way you will have in hole surface mount. :p
     
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  10. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    I think the OP has a Fluke 87 - they run at 6000 counts in low res and 20000 counts in high res mode.
     
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  11. Dr.killjoy

    Thread Starter Well-Known Member

    Apr 28, 2013
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    Thanks I have the Fluke 87 series II and every meter I own is autoranging hence it's design but what I will do is try to find a suitable Vref below 2v and build a seperate design if you would like ??
     
  12. Dr.killjoy

    Thread Starter Well-Known Member

    Apr 28, 2013
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    Thanks grammer nazi..:p:)
     
  13. tcmtech

    Distinguished Member

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    Well you are now the first to have ever called me that! :eek:

    I've always rather considered myself to be a grammar pollock.:p
     
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  14. tcmtech

    Distinguished Member

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    So basically all he just needs a 2 volt ~(+-.1 volt) reference. The other two lower sets of numbers is just to make him feel like the money he wasted on the made in china meter was justified.
     
  15. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    What made-in-America devices do you use?
     
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  16. Dr.killjoy

    Thread Starter Well-Known Member

    Apr 28, 2013
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    I choose the voltage because it was the lowest voltage with the best specs I could find .... I have a couple flukes and bought them used and they still work perfectly .. The reason I choose them was because for the price of a quality Chinese unit I could get a used fluke that might save my life or someone else if something where to happen..
    The purpose for the build is so any one can build a quality Vref for say under $10.00..
     
  17. DickCappels

    Moderator

    Aug 21, 2008
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    If you can make it all surface mount you will certainly save yourself some trouble drilling holes. If you some of the parts you need to use only come in through-hole packages, you can probably mount them on the surface anyway. You should should not feel shy about using the most practical approach.

    [​IMG]
     
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  18. tcmtech

    Distinguished Member

    Nov 4, 2013
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    None. I'm not brand or place of origin loyal. I own many devices that come from far off countries that cost way less than what made in America brands charge for similar quality or lack thereof.

    I'm pretty sure all of my multimeters come from somewhere that doesn't tack a 200+ % markup legacy fee on to their products because of what their name once stood for. :p
     
  19. Lestraveled

    Well-Known Member

    May 19, 2014
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    @Dr.killjoy
    What you are building is called a "transfer Reference". (I have one based on the AD587LQ for 10 volts.) After temperature cycling it for so many times you can send it to a cal lab and they can trim it to your preferred voltage for a pretty cheap price. They send it back to you and you have a great voltage reference to compare your meters to.
     
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  20. Dr.killjoy

    Thread Starter Well-Known Member

    Apr 28, 2013
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    Sorry for the no updates but I have had work and alot of repairs that needed to be done ..
    I looked in too a Vref below 1.99v and found some ok IC chip but can't match the tolerance of 2.048v IC... So I would just use DickCappels design posted below..
    My only problem right now I am working on is finding the right P-fet to work with 18650 cell ...
    I was looking at the FQPF9P25YDTU but not sure if would work or is there a better choice..









    Thanks for the advice and helps out alot ..
    I am happy with the voltage I choose but will have to check that out..
    Thanks
     
    Last edited: Apr 24, 2016
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