[volt-nuts] Traveling Standards

[Bob Smither]

Fellow Voltage Fans,

To review - I would like to have a lab standard here that I can trust to 
10 ppm or better to use to calibrate my expanding collection of 
voltmeters.  I have proposed to built a portable standard that I will 
ship to participating volt nuts on this list who will record their 
readings of the standard and share those readings with the list.

I have designed a Traveling Standard that incorporates two references 
(an LM199AH and a MAX6350E) along with an LM34 to measure the 
temperature of the MAX6350 (the LM34 is glued to the top of the MAX6350.

The schematic is attached to this page:

   http://www.c-c-i.com/TS

Following suggestions on this list (thanks!) I will use an external 
"wall wart" supply for the input 24 Volts.  This reduces any shift 
caused by the line regulation of the three terminal regulator.

My design notes are included on the above page.

I have constructed a bread board of the circuit on a plugboard.  I will 
move the circuit to a printed circuit version after some testing.

Some preliminary readings from the breadboard of the LM199AH part are 
noted on this page:

   http://c-c-i.com/node/121

Note that these readings are taken with an HP3455A which has not been 
calibrated since I bought it new.  I would expect the accuracy to be no 
better than .01% and may be much worse.

My plan is to mount the printed circuit board version in a short length 
of 2" PVC pipe with connectors for the three outputs.

After the printed circuit board version is aged some it will be ready to 
ship.

Are there any more on the list that would be willing to make a 
measurement of the Traveling Standard?

I will collect the readings that we collectively get on the TS and make 
them available to the list.  I anticipate that with some experience we 
can all benefit from having this TS well aged and with a well known 
output voltage.

I will handle the shipping - all I ask is that you take careful 
measurements and provide them to me, then return the unit.

Thanks!

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