[volt-nuts] Matched resistors

[acbern at gmx.de]

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.stellmach at freenet.de>
> An: volt-nuts at 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. 
> P<10mW.
> 
> 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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