[volt-nuts] Matched resistors

Randy Evans randyevans2688 at gmail.com
Sat Jul 19 00:07:40 EDT 2014


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 <randyevans2688 at 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, <acbern at 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.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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