Re: [volt-nuts] Matched resistors

2014-07-18 Thread Randy Evans
I figured out that VPG is Vishay Precision Group but I have not managed to
identify the vhd hermetic divider.  Could you point me to the location on
the Vishay web site?

Thanks,

Randy


On Fri, Jul 18, 2014 at 9:00 PM, Randy Evans randyevans2...@gmail.com
wrote:

 I am not familiar with vpg or vhd terms.  I assume the former is a
 company (European?) and the latter is a model type?  Do you have a URL or
 other information to get followup information.  The 0.1 ppm tracking is
 exactly what I am looking for and I don't need absolute accuracy.

 Thanks,

 Randy


 On Fri, Jul 18, 2014 at 12:00 AM, acb...@gmx.de wrote:

 randy,
 re. vpg: they offer an hermetic divider (vhd) with typ. 0.1ppm tracking
 of tempco. if you are ok with lowest available abs. accuracy it will be
 well priced, I remember having asked them for a price and it was below 50€
 for standard lead time (which can be very long). it is also fair to assume
 it would age more homogeneously than two separate resistors, also you dont
 need to think about how to keep two resistors at the same temp. make sure
 each resistor is loaded with less than 10mw, otherwise aging may be above
 what the claim in their collateral.



  Gesendet: Donnerstag, 17. Juli 2014 um 04:40 Uhr
  Von: Frank Stellmach frank.stellm...@freenet.de
  An: volt-nuts@febo.com
  Betreff: [volt-nuts] Matched resistors
 
  Randy,
 
  resistor matched in T.C. are extremely expensive, as the manufacturer
  (or yourself) would have to select these from a batch of many samples.
 
  reistors with very small T.C. (1ppm/K) would do the job also, but they
  also need to be stable over time, in shelf life opereation mode, i.e.
  P10mW.
 
  That means, you need those hermetically sealed VHP202Z from Vishay, T.C.
  is typically  1ppm/K and they are stable to  2ppm over 5years. But
  they cost already 80€ each, depending on tolerance.
 
  I made a longterm observation of these and found these parameters
 confirmed.
 
  Frank
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Re: [volt-nuts] Matched resistors

2014-07-18 Thread Andreas Jahn

http://www.vishaypg.com/foil-resistors/list/product-63036/
http://www.vishaypg.com/doc?63036

Am 19.07.2014 06:07, schrieb Randy Evans:

I figured out that VPG is Vishay Precision Group but I have not managed to
identify the vhd hermetic divider.  Could you point me to the location on
the Vishay web site?

Thanks,

Randy


On Fri, Jul 18, 2014 at 9:00 PM, Randy Evans randyevans2...@gmail.com
wrote:


I am not familiar with vpg or vhd terms.  I assume the former is a
company (European?) and the latter is a model type?  Do you have a URL or
other information to get followup information.  The 0.1 ppm tracking is
exactly what I am looking for and I don't need absolute accuracy.

Thanks,

Randy


On Fri, Jul 18, 2014 at 12:00 AM, acb...@gmx.de wrote:


randy,
re. vpg: they offer an hermetic divider (vhd) with typ. 0.1ppm tracking
of tempco. if you are ok with lowest available abs. accuracy it will be
well priced, I remember having asked them for a price and it was below 50€
for standard lead time (which can be very long). it is also fair to assume
it would age more homogeneously than two separate resistors, also you dont
need to think about how to keep two resistors at the same temp. make sure
each resistor is loaded with less than 10mw, otherwise aging may be above
what the claim in their collateral.




Gesendet: Donnerstag, 17. Juli 2014 um 04:40 Uhr
Von: Frank Stellmach frank.stellm...@freenet.de
An: volt-nuts@febo.com
Betreff: [volt-nuts] Matched resistors

Randy,

resistor matched in T.C. are extremely expensive, as the manufacturer
(or yourself) would have to select these from a batch of many samples.

reistors with very small T.C. (1ppm/K) would do the job also, but they
also need to be stable over time, in shelf life opereation mode, i.e.
P10mW.

That means, you need those hermetically sealed VHP202Z from Vishay, T.C.
is typically  1ppm/K and they are stable to  2ppm over 5years. But
they cost already 80€ each, depending on tolerance.

I made a longterm observation of these and found these parameters

confirmed.

Frank
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