[volt-nuts] Resistors for LTZ1000A circuit
Frank Stellmach
frank.stellmach at freenet.de
Tue Dec 10 01:41:25 EST 2013
Hello Randy,
yes. It's not necessary to use (molded) metal foil reistors from Vishay.
Precision wirewound resistors, T.C. = 3ppm/K and specified for annual
drift (<20ppm/yr.) are as good as latter ones.
You may achieve stabilities well below 1ppm/yr. for the reference, if
you keep the stabilization temperature as low as possible, the A version
perhaps at 50..55°C, (12.5k/1k or 25k/2k recommended) instead of 45°C as
for the non A version.
I've described the theoretical background and measurements on my LTZ1000
references (2 on my own, one identical of another volt-nut) parts #1
-#6, starting here:
http://www.eevblog.com/forum/projects/ultra-precision-reference-ltz1000/165/
Those 0.1% wirewound resistors, are available from stock, they are
called "econistors", 8G16, cost around 8$/€ each and are distributed via
a british company
http://www.rhopointcomponents.com/components/resistors/precision-through-hole.html
regards Frank
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