[volt-nuts] Best reference after LTZ1000

Andrea Baldoni erm191ba3 at ermione.com
Mon Aug 16 10:36:40 UTC 2010

On Sun, Aug 15, 2010 at 03:34:29PM -0400, Marvin E. Gozum wrote:

> What do you think of Geller's work?  He uses the AD587 as a voltage  
> reference, and writes of results > = the AD specs.

I think the same of voltagestandard.com. These boards adds nothing to the
original chips they use (the chips are not selected)... they may
eventually just degrade performance with layout/mechanical stresses/passive
The calibration service they offer, because it is applied to this kind of
references, is not useful as a "transfer" to anyone with already decent
instruments (with better references inside).

> Your need seems close to the principle used in his thermal anemometer,  
> which he patented.  IIRC, it measures temperature change as changes in 
> the stable voltage response of a reference, which is then proportionate 
> to air current.

As far as I can see from the circuit, he uses that poor LM399 just as
heater resistor and RTD. The reference diode is unconnected.
The reference of the wheatstone bridge is the +15V power.

I don't see what kind of principle he could have patented. Hot wire anemometers
are not a new and this is the worst one I could imagine.

Maybe he has tried to use the LM399 to sell voltage references, he has failed
to obtain good results (it's not so easy to use as the AD587) and having
already bought some (and probably having burned the diode...) he recycled them
in this kit...

Best regards,
Andrea Baldoni

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