I saw the other day a Keithley 2636B SMU which has 0.1fA resolution @
10uV in a normal Keithley DMM box size. Keithley also have some
systems with external amps that go down even further, to tens of
atto-Amp regions. Even the old HP resolves down to 1fA.
It made me curious.
Dear list: What's the
As far as I know, the 3458A was bought by the thousands by defense and
space organizations. I'd guess no-one else would support that kind of
development. Well maybe the telecom sector if there was a need for
such an instrument.
No one else ever will. *WAY* too expensive for even Keysight to
It's reply #984 in the thread. See also #982
http://www.eevblog.com/forum/projects/ultra-precision-reference-ltz1000/msg605967/#msg605967
Direct to plot file of reply #984
http://www.eevblog.com/forum/projects/ultra-precision-reference-ltz1000/?action=dlattach;attach=135476
Direct to plot file
I posted a plot of calculated resistor values versus temperature in
the LTZ1000 thread on the EVV blog yetserday. Email me if you can't
find it.
I guess the 3458A was specified to be used at north pole and desert
heat, that's why they have such a high temperature setting. They could
have a
Hi,
Does someone know what reference is used in the Signametrics/Agilent 2060x?
I have had an unused SMU2064 on the shelf for some time. Recently I
powered it up and found it very noisy compared to my LTZ1000 based
DMMs. It seems I can get around 6.5 digit resolution from this DMM,
noise is in
Hi,
Does anyone have a clean 3458A reference board, ie PCB without components?
Throw it in the copier? Or would that violate some copyright?
In that case, a board outline (board measurements, hole and connector
footprints ...) would be enough. I don't have a 3458A to dig into,
otherwise, I'd do
It's no coincidence that virtually all 8.5 digit DMMs use the LTZ1000.
It's in a class of it's own. REF102 is not in the same class, even if
you average a handful.
But there are a couple of nice things about the REF102, though for
more moderate requirements
- You get a reference at 10V,
I'm well aware of the differences between the two, having used / built
boards with both, and also made quite extensive measurements on both.
My comment was about some posts on this list about two months ago,
about resistors for them, and some observations that are perhaps not
obvious from the
I have been off the list for a while, but noticed that there where
some posts on the LTZ1000 and LM399 about a month ago.
I just have a comment; the requirements on these two references
(standard datasheet implementations) are very much opposites:
- LTZ1000 requires very stable resistors but is
I have a Signametrics SMU2064 usb box. Signametrics where bought by Agilent
in 2010? and Agilent do not maintain software /drivers any more.
I'd like to run it under W64 if I could find usb drivers / updates.
It seems like Pickering, Marvin are producing some of the Signametrics
boxes, at least
Not sure if I already posted this:
From the replies, it seems Transfer Accuracy is not really defined, open
for interpretations. It is perhaps not very important either, as short term
stability is usually specified.
___
volt-nuts mailing list --
Thanks for all the replies. Looking at all of them, I'd say the meaning or
understanding of Transfer Accuracy is quite fuzzy, or has a lot of room for
interpretation. While not a terribly important term to have a common
understanding of, it still it has a bit of volt-nut interest..
It was the April 1989 HP journal that made me post the question. The
article makes really good reading about the core of the 3458. It also made
me think about how one could implement the AD with the components available
today and bench instruments. It should not take that many parts to make a
I was looking at a few different alternatives for a transportable,
non-permanently powered on, DIY, voltage reference and I picked the LM399
as one of the candidates.
The LM399 is a buried zener reference with built-in temperature regulation
and an integrated thermal insulation cover. It is very
Yes, LM399 good good! Me like!
The dozen LM399 have now spent a day at an average 0.0uV deviation, +/-0.2u
peak to peak probably below 0.1ppm rms (10s averaged), despite the room
temperature changing by something like 5 degrees (C). Condition; Bench
supply 12V, 12 IC paralleled, current limited
Willy,
Correct, with important assumptions:
- that the uncertainty of each one is randomly independent of the other.
- i think one also assumes the overall uncertainties have to have a
Gaussian distribution.
If you grab a handful of components / units, they may, or may not, show
independently
Maybe I should not be posting this on the VN list, as it is only indirectly
related to volts.
Still; I have been getting some messages and feedback, with no disrespect
to me, asking, if I know what I am doing. With no disrespect to the people
who replied, of or on list (on the contrary, I'm
-nuts digest...
Today's Topics:
1. Temperature controller for ovenizing and temperature cycling
(Jan Fredriksson)
2. Re: Temperature controller for ovenizing and temperature
cycling (ed breya
The base-drain Q1 and Q2 can of course be used. The problem is that the
base-drain voltages to temperature is only approximately known. You would
need to calibrate those, using external heating. As they can be be expected
to be linear, you only need two or three temperature points for an decent
Any voltnut bought one yesterday from Ebay?
Looks like a nice box and a very decent price.
Tell us more!
I'd like a pair as volume control for my stereo :-)
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To unsubscribe, go to
One thing that strikes me reading old 3458A product datasheet from HP is
that they stressed the high measurement speed, 100kHz @ 16 bit, but not
empasizing much the DC accuracy. Now, the 3458A remains state of the art in
DC accuracy / liearity, but for high speed measurements and of course
Frank wrote:
3. The 3458A still has got the best linear A/D, around 0.02ppm of input.
Is that a typo? Even 0.2 ppm would seem extremely good. I think I saw an
official number of 0.1ppm somewhere. Probably 0.1ppm of range. And how do
they implement that? Manual trimming and compensation?
I'm thinking of using a PWM divider for voltage generation of adjustable DC
voltages from a voltage reference.
Does anyone have any pointers to circuits, solutions, topologies, error
analysis etc. for such solutions?
Jan
___
volt-nuts mailing list --
Wow, that triggered a lot of replies, thanks!!!
Now I think I would like to change the subject of the posting to Voltage
divider; what I want to do is generate voltages (from a voltage reference)
by whatever tecnology is practical. I ruled out resistor divider as to
complex and then PWM seemed an
divider (John Devereux)
2. Re: PWM voltage divider / now Voltage divider (Jan Fredriksson)
--
Message: 1
Date: Wed, 08 Jan 2014 13:53:02 +
From: John Devereux j...@devereux.me.uk
To: volt-nuts@febo.com
Subject: Re
Hi list,
None of the resistors actually need to be high presision. They need to have
the best possible stability, time, temperature wise. But actual resistance
values are not critical.
It would require a longer discussion to sort out all the why /how to select
resistor values...
Den 11 dec 2013
Throwing in my 2C on 5-1/2 - 6-1/2 digit DMMs on a budget
I have had a few Solartron / Schlumberger 7150, 7150 plus, 7151, 5-1/2
6-1/2 digit DMMs
Pro:
- available at very good prices on the net (especially in the UK?). I think
I paid around £50 for them. Except one bought brand new 20+ years
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