[volt-nuts] Traveling Standards

[Bob Smither]

Andreas Jahn wrote:
>> Andreas mentioned the lm339.  One candidate I am considering is the
>> lm119ah.
> 
> not LM339 (it is a comparator) but the LM399 is a heated reference.
> 
> really LM119AH? or LM129AH (I cannot find a reference when looking for 
> LM119)
> 
> And the LM129AH has a tempco of around 6 ppm/K.
> so you will have either to heat it or to monitor the temperature exactly.

My bad - I should never do e-mails after midnight!

I meant, of course, your reference to the lm399.  I have 3 lm199ah parts 
that I was referring to.  The spec sheet shows max TC of .5ppm/C.

> But consider: when you maintain only one reference you are the happy man 
> with one clock.

   :-)

> And you will never mention when the reference will drift by shipping.
> I would maintain at least 4 equal references. Shipping only one at a time.
> And comparing to the other 3 local references before and after shipment.

Excellent idea.  Well I have three lm199ah and three lm399ah (not quite 
as good).  My construction project just expanded.

Thanks!

-- 
Bob Smither, PhD                                   Circuit Concepts, Inc.
=========================================================================
"Our enemies are innovative and resourceful, and so are we. They never
stop thinking about new ways to harm our country and our people, and
neither do we."
   --George W. Bush, August 5,2004
      http://www.whitehouse.gov/news/releases/2004/08/20040805-3.html
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Smither at C-C-I.Com  http://www.C-C-I.Com  281-331-2744(office)  -4616(fax)




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