Project hit a bump on a road, called long leadtime for precision resistors. But it's not dead yet, while I'm waiting on VPG order, managed to score some custom Fluke wirewounds, VPG VPR5's and VCS101's for current domain of project.
Also some time ago I did got current sensor, almighty zeroflux LEM Ultrastab 600S. It's the only current transducer with specced 1ppm linearity error and 0.2ppm/K tempco, with veeery wide range
As with most magnetic current transducers, performance likely to be be limited to burden resistors and attentuation circuitry on secondary.
Anyway, enough text, here are photos of goodies:
(Everything clickable as usual)
What is that?
Those are wire-wound Fluke resistors. They are huge.
This is 250Kohm, 2W 0.05% 5ppm/°C one.
See that tiny spot in center? That's generic SMD resistor 1206 390ohm.
These are constructed like an inductors, so no doubt they are inductive, but for DC circuitry that can be workarounded.
50K measurement:
Also scored Vishay PG VPR5 1.0000R's (7pcs)
Aren't they beautiful?
Good match to LEM's.. tiny thing in center - LTZ1000.
Quick check, source 10mA from Keithley 2400, measure voltage on sense terminals with 2002.
Also got some constantan (Copper+Nickel 44) wire for finetuning, made in 1988
.
If believe factory label, it's 0.07 mm diameter, 127 ohm per meter. It's coated wire for isolation.
So that's all for today:
Total list of parts:
http://dev.xdevs.com/issues/1068I'll meet VPG rep tomorrow, they promised some demo
Notice - if anyone decided up for assembled LTZ1000's VREFs - this week is last call, as I'm going to order LTZ's from Linear next monday. This is hobby project funded from own pocket, so there will be no excessive stock of expensive parts.