Re: Batteries for voltage reference

David L. Jones wrote:
On Oct 22, 11:16 am, hal-use...@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx (Hal
Murray) wrote:
I remember tales from many many years ago about using fresh batteries
as a simple, cheap, and readily available voltage reference.

Has anybody tested that recently?

Assume I'm using standard AA alkaline batteries. How much do they
vary over temperature, age, and from brand to brand? How much
do they vary over manufacturing time within the same brand?

There has been extensive discussion on this in the past, Google will
show you.
But this idea is just so antiquated now it's not even worth
considering.

Are there other inexpensive references that are easily available?

Yes, bandgap voltage reference IC's are available that do just this.
They can cost anywhere from a few 10's of cents to a few 10's of
dollars depending on the specs.

Digikey have thousands of items listed:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=2556223;keywords=voltage%20reference

0.1% ones cost only a few dollars for example.

Dave.


The biggest problem with standard cells for lab use is their horrible temperature coefficient. Batteries are a great deal quieter than voltage references, which sometimes matters more than long term stability...but as someone else suggested, a LED can be useful when you need a quiet reference.

A red LED with its cathode grounded, running at constant current and buffered by an NPN emitter follower makes nice quiet 1V reference with lowish tempco, due to the TC of the LED and the Vbe more or less cancelling. Give it some reasonable current, and this can easily be 15 dB quieter than a bandgap. (Bandgaps use junction forward voltages too, but have to multiply up a smaller voltage, leading to more noise.)

Cheers,

Phil Hobbs
.

Relevant Pages

  • Re: Batteries for voltage reference
    ... Assume I'm using standard AA alkaline batteries. ... vary over temperature, age, and from brand to brand? ... Search for voltage reference on Digikey or Mouser or other. ...
    (sci.electronics.design)
  • Re: Weston Cells
    ... to get a replacement cell. ... If I wanted a chemical primary voltage standard I suppose I'd start ... If *I* were wanting a voltage reference on the cheap I think I'd use ... design your own if you go with one that requires a power source: ...
    (sci.electronics.design)
  • Re: Weston Cells
    ... Jim Thompson wrote: ... Did you know that NIST and CERN now use Zener circuits (as a secondary standard calibrated to a Josephson junction) because the latter is more stable than a Weston cell? ... If *I* were wanting a voltage reference on the cheap I think I'd use ...
    (sci.electronics.design)
  • Re: Weston Cells
    ... to get a replacement cell. ... now use Zener circuits (as a secondary standard calibrated to a ... If I wanted a chemical primary voltage standard I suppose I'd start ... If *I* were wanting a voltage reference on the cheap I think I'd use ...
    (sci.electronics.design)
  • Re: Batteries for voltage reference
    ... as a simple, cheap, and readily available voltage reference. ... Assume I'm using standard AA alkaline batteries. ... vary over temperature, age, and from brand to brand? ...
    (sci.electronics.design)