JL
J. L. Trantham
Thu, Sep 22, 2011 1:37 AM
I purchased an eBay item (190538109632) for the 'Standard Cell' that included another item.
What is it?
The 'Standard Cell' is an 'Eppley Laboratory Catalog Number 100 (SN 762058) Low Termperature Coefficient Standard of E. M. F.' that has written on it '1.01931 @ 20 degree C' with a date of what I think is '2-4-69' which I think means Feburary 4, 1969.
Using my 'new' Solartron 7081, I read the voltage at 1.017844 +/- about 1 uV. If I have the math correct, that is a decrease of about 35 uV/yr which, I think, is about what is predicted for these cell's, assuming my 7081 is accurate.
I also have another Eppley Standard Cell (SN 821855) that reads 1.018709 but no date or prior reading on the unit.
On another, unrelated note, I have been able to chase down the US branch of Ametek in Oak Ridge, TN, and they will be getting my 7081 back to send to England for calibration and 'service best effort', given that the meter ceased production in 1998 with end of support 2008. TAT is about 4 weeks in England.
Now, what is that other thing in the listing?
Joe
I purchased an eBay item (190538109632) for the 'Standard Cell' that included another item.
What is it?
The 'Standard Cell' is an 'Eppley Laboratory Catalog Number 100 (SN 762058) Low Termperature Coefficient Standard of E. M. F.' that has written on it '1.01931 @ 20 degree C' with a date of what I think is '2-4-69' which I think means Feburary 4, 1969.
Using my 'new' Solartron 7081, I read the voltage at 1.017844 +/- about 1 uV. If I have the math correct, that is a decrease of about 35 uV/yr which, I think, is about what is predicted for these cell's, assuming my 7081 is accurate.
I also have another Eppley Standard Cell (SN 821855) that reads 1.018709 but no date or prior reading on the unit.
On another, unrelated note, I have been able to chase down the US branch of Ametek in Oak Ridge, TN, and they will be getting my 7081 back to send to England for calibration and 'service best effort', given that the meter ceased production in 1998 with end of support 2008. TAT is about 4 weeks in England.
Now, what is that other thing in the listing?
Joe
JF
J. Forster
Thu, Sep 22, 2011 2:34 AM
If the Standard Cell has been shaken (in shipping) it needs to sit a long
time before being useful as a standard. Some types of cells really do not
like being inverted. It is designed to work into an open circuit.... ie:
potentiometric comparison.
The other item is abn Eppley Thermopile. The mpount is probably Spindler &
Hoyer, and it fits Zeiss standard profile optical benches, made of
aluminum or cast iron (most often).
Inside the can, there is a metal disk that should be painted with a very,
very flat black paint. The paint absorbs radiation from VUV to X-rays and
turns the radiation into heat. The rear of the disk has a myriad of tiny
thermocouples. The cold side goes to the case. The terminals are usually
solid Cu.
In use, it is usually read out w/ a nanovoltmeter. They are usually
calibrated in mV/W. You will likely need a fairly strong light to see much
voltage.
Since it is a calorimeter, it can be used to compare the power in two
optical lines of widely disparate wavelengths.
Best,
-John
=============
I purchased an eBay item (190538109632) for the 'Standard Cell' that
included another item.
What is it?
The 'Standard Cell' is an 'Eppley Laboratory Catalog Number 100 (SN
762058) Low Termperature Coefficient Standard of E. M. F.' that has
written on it '1.01931 @ 20 degree C' with a date of what I think is
'2-4-69' which I think means Feburary 4, 1969.
Using my 'new' Solartron 7081, I read the voltage at 1.017844 +/- about 1
uV. If I have the math correct, that is a decrease of about 35 uV/yr
which, I think, is about what is predicted for these cell's, assuming my
7081 is accurate.
I also have another Eppley Standard Cell (SN 821855) that reads 1.018709
but no date or prior reading on the unit.
On another, unrelated note, I have been able to chase down the US branch
of Ametek in Oak Ridge, TN, and they will be getting my 7081 back to send
to England for calibration and 'service best effort', given that the meter
ceased production in 1998 with end of support 2008. TAT is about 4 weeks
in England.
Now, what is that other thing in the listing?
Joe
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
If the Standard Cell has been shaken (in shipping) it needs to sit a long
time before being useful as a standard. Some types of cells really do not
like being inverted. It is designed to work into an open circuit.... ie:
potentiometric comparison.
The other item is abn Eppley Thermopile. The mpount is probably Spindler &
Hoyer, and it fits Zeiss standard profile optical benches, made of
aluminum or cast iron (most often).
Inside the can, there is a metal disk that should be painted with a very,
very flat black paint. The paint absorbs radiation from VUV to X-rays and
turns the radiation into heat. The rear of the disk has a myriad of tiny
thermocouples. The cold side goes to the case. The terminals are usually
solid Cu.
In use, it is usually read out w/ a nanovoltmeter. They are usually
calibrated in mV/W. You will likely need a fairly strong light to see much
voltage.
Since it is a calorimeter, it can be used to compare the power in two
optical lines of widely disparate wavelengths.
Best,
-John
=============
> I purchased an eBay item (190538109632) for the 'Standard Cell' that
> included another item.
>
> What is it?
>
> The 'Standard Cell' is an 'Eppley Laboratory Catalog Number 100 (SN
> 762058) Low Termperature Coefficient Standard of E. M. F.' that has
> written on it '1.01931 @ 20 degree C' with a date of what I think is
> '2-4-69' which I think means Feburary 4, 1969.
>
> Using my 'new' Solartron 7081, I read the voltage at 1.017844 +/- about 1
> uV. If I have the math correct, that is a decrease of about 35 uV/yr
> which, I think, is about what is predicted for these cell's, assuming my
> 7081 is accurate.
>
> I also have another Eppley Standard Cell (SN 821855) that reads 1.018709
> but no date or prior reading on the unit.
>
> On another, unrelated note, I have been able to chase down the US branch
> of Ametek in Oak Ridge, TN, and they will be getting my 7081 back to send
> to England for calibration and 'service best effort', given that the meter
> ceased production in 1998 with end of support 2008. TAT is about 4 weeks
> in England.
>
> Now, what is that other thing in the listing?
>
> Joe
> _______________________________________________
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> and follow the instructions there.
>
>
JL
J. L. Trantham
Thu, Sep 22, 2011 2:49 AM
Well, it/they arrived today. I will leave both my 'Standard Cells' sitting
side by side and recheck later this week or next week and see what the
measurements are.
In the mean time, I will have to see what I can measure from the
'Thermopile' and find some boxes to pack up the 7081 for shipment.
Joe
----- Original Message -----
From: "J. Forster" jfor@quikus.com
To: "Discussion of precise voltage measurement" volt-nuts@febo.com
Sent: Wednesday, September 21, 2011 9:34 PM
Subject: Re: [volt-nuts] Eppley Standard Cell and What Is It?
If the Standard Cell has been shaken (in shipping) it needs to sit a long
time before being useful as a standard. Some types of cells really do not
like being inverted. It is designed to work into an open circuit.... ie:
potentiometric comparison.
The other item is abn Eppley Thermopile. The mpount is probably Spindler &
Hoyer, and it fits Zeiss standard profile optical benches, made of
aluminum or cast iron (most often).
Inside the can, there is a metal disk that should be painted with a very,
very flat black paint. The paint absorbs radiation from VUV to X-rays and
turns the radiation into heat. The rear of the disk has a myriad of tiny
thermocouples. The cold side goes to the case. The terminals are usually
solid Cu.
In use, it is usually read out w/ a nanovoltmeter. They are usually
calibrated in mV/W. You will likely need a fairly strong light to see much
voltage.
Since it is a calorimeter, it can be used to compare the power in two
optical lines of widely disparate wavelengths.
Best,
-John
=============
I purchased an eBay item (190538109632) for the 'Standard Cell' that
included another item.
What is it?
The 'Standard Cell' is an 'Eppley Laboratory Catalog Number 100 (SN
762058) Low Termperature Coefficient Standard of E. M. F.' that has
written on it '1.01931 @ 20 degree C' with a date of what I think is
'2-4-69' which I think means Feburary 4, 1969.
Using my 'new' Solartron 7081, I read the voltage at 1.017844 +/- about 1
uV. If I have the math correct, that is a decrease of about 35 uV/yr
which, I think, is about what is predicted for these cell's, assuming my
7081 is accurate.
I also have another Eppley Standard Cell (SN 821855) that reads 1.018709
but no date or prior reading on the unit.
On another, unrelated note, I have been able to chase down the US branch
of Ametek in Oak Ridge, TN, and they will be getting my 7081 back to send
to England for calibration and 'service best effort', given that the
meter
ceased production in 1998 with end of support 2008. TAT is about 4 weeks
in England.
Now, what is that other thing in the listing?
Joe
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
Well, it/they arrived today. I will leave both my 'Standard Cells' sitting
side by side and recheck later this week or next week and see what the
measurements are.
In the mean time, I will have to see what I can measure from the
'Thermopile' and find some boxes to pack up the 7081 for shipment.
Joe
----- Original Message -----
From: "J. Forster" <jfor@quikus.com>
To: "Discussion of precise voltage measurement" <volt-nuts@febo.com>
Sent: Wednesday, September 21, 2011 9:34 PM
Subject: Re: [volt-nuts] Eppley Standard Cell and What Is It?
> If the Standard Cell has been shaken (in shipping) it needs to sit a long
> time before being useful as a standard. Some types of cells really do not
> like being inverted. It is designed to work into an open circuit.... ie:
> potentiometric comparison.
>
> The other item is abn Eppley Thermopile. The mpount is probably Spindler &
> Hoyer, and it fits Zeiss standard profile optical benches, made of
> aluminum or cast iron (most often).
>
> Inside the can, there is a metal disk that should be painted with a very,
> very flat black paint. The paint absorbs radiation from VUV to X-rays and
> turns the radiation into heat. The rear of the disk has a myriad of tiny
> thermocouples. The cold side goes to the case. The terminals are usually
> solid Cu.
>
> In use, it is usually read out w/ a nanovoltmeter. They are usually
> calibrated in mV/W. You will likely need a fairly strong light to see much
> voltage.
>
> Since it is a calorimeter, it can be used to compare the power in two
> optical lines of widely disparate wavelengths.
>
> Best,
>
> -John
>
> =============
>
>
>
>
>> I purchased an eBay item (190538109632) for the 'Standard Cell' that
>> included another item.
>>
>> What is it?
>>
>> The 'Standard Cell' is an 'Eppley Laboratory Catalog Number 100 (SN
>> 762058) Low Termperature Coefficient Standard of E. M. F.' that has
>> written on it '1.01931 @ 20 degree C' with a date of what I think is
>> '2-4-69' which I think means Feburary 4, 1969.
>>
>> Using my 'new' Solartron 7081, I read the voltage at 1.017844 +/- about 1
>> uV. If I have the math correct, that is a decrease of about 35 uV/yr
>> which, I think, is about what is predicted for these cell's, assuming my
>> 7081 is accurate.
>>
>> I also have another Eppley Standard Cell (SN 821855) that reads 1.018709
>> but no date or prior reading on the unit.
>>
>> On another, unrelated note, I have been able to chase down the US branch
>> of Ametek in Oak Ridge, TN, and they will be getting my 7081 back to send
>> to England for calibration and 'service best effort', given that the
>> meter
>> ceased production in 1998 with end of support 2008. TAT is about 4 weeks
>> in England.
>>
>> Now, what is that other thing in the listing?
>>
>> Joe
>> _______________________________________________
>> volt-nuts mailing list -- volt-nuts@febo.com
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
>> and follow the instructions there.
>>
>>
>
>
>
> _______________________________________________
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> and follow the instructions there.
G
gbusg
Thu, Sep 22, 2011 3:58 AM
Some types of cells really do not
like being inverted. It is designed to work into an open circuit.... ie:
potentiometric comparison.
From the Solartron 7081 specs I see its DCV input resistance is >10G ohms for 0.1 thru 10 V ranges.
Have any of you Solartron 7081 users looked to see if there are reverse switching transients present at its front DCV input jack while in its DCV mode?
In the case of the HP 3458A, you can temporarily turn-off Auto-Zero, which, I think should minimize if not eliminate any possible switching transients present at its front DCV input terminals. By comparison I'm not sure how this works with the Solartron 7081?
Disclaimer: I've not personally characterized any possible reverse switching transients present at the 3458A input terminals. But, in theory I think I'd temporarily turn-off Auto-Zero immediately prior to connecting to the Eppley.
Admittedly the Eppley was originally designed to work into infinite load resistance (potentiometric comparison back in the old days when DCV meter input resistance was lower than for the 7081 and 3458A).
Comments?
Greg
John wrote:
>Some types of cells really do not
>like being inverted. It is designed to work into an open circuit.... ie:
>potentiometric comparison.
>From the Solartron 7081 specs I see its DCV input resistance is >10G ohms for 0.1 thru 10 V ranges.
Have any of you Solartron 7081 users looked to see if there are reverse switching transients present at its front DCV input jack while in its DCV mode?
In the case of the HP 3458A, you can temporarily turn-off Auto-Zero, which, I *think* should minimize if not eliminate any possible switching transients present at its front DCV input terminals. By comparison I'm not sure how this works with the Solartron 7081?
Disclaimer: I've not personally characterized any possible reverse switching transients present at the 3458A input terminals. But, in theory I think I'd temporarily turn-off Auto-Zero immediately prior to connecting to the Eppley.
Admittedly the Eppley was originally designed to work into infinite load resistance (potentiometric comparison back in the old days when DCV meter input resistance was lower than for the 7081 and 3458A).
Comments?
Greg
G
gbusg
Thu, Sep 22, 2011 7:05 AM
P.S. Conrad Hoffman has good info on the topic of Weston saturated and
un-saturated standard cells.
According to his info, even high resistance input modern DMMs shouldn't be
used to directly measure the output of Weston standard cells.
See:
http://conradhoffman.com/stdcell.htm
Greg
----- Original Message -----
From: "gbusg" gbusg@comcast.net
To: jfor@quikus.com; "Discussion of precise voltage measurement"
volt-nuts@febo.com
Sent: Wednesday, September 21, 2011 9:58 PM
Subject: Re: [volt-nuts] Eppley Standard Cell and What Is It?
John wrote:
Some types of cells really do not
like being inverted. It is designed to work into an open circuit.... ie:
potentiometric comparison.
From the Solartron 7081 specs I see its DCV input resistance is >10G ohms
for 0.1 thru 10 V ranges.
Have any of you Solartron 7081 users looked to see if there are reverse
switching transients present at its front DCV input jack while in its DCV
mode?
In the case of the HP 3458A, you can temporarily turn-off Auto-Zero, which,
I think should minimize if not eliminate any possible switching transients
present at its front DCV input terminals. By comparison I'm not sure how
this works with the Solartron 7081?
Disclaimer: I've not personally characterized any possible reverse switching
transients present at the 3458A input terminals. But, in theory I think I'd
temporarily turn-off Auto-Zero immediately prior to connecting to the
Eppley.
Admittedly the Eppley was originally designed to work into infinite load
resistance (potentiometric comparison back in the old days when DCV meter
input resistance was lower than for the 7081 and 3458A).
Comments?
Greg
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
P.S. Conrad Hoffman has good info on the topic of Weston saturated and
un-saturated standard cells.
According to his info, even high resistance input modern DMMs shouldn't be
used to directly measure the output of Weston standard cells.
See:
http://conradhoffman.com/stdcell.htm
Greg
----- Original Message -----
From: "gbusg" <gbusg@comcast.net>
To: <jfor@quikus.com>; "Discussion of precise voltage measurement"
<volt-nuts@febo.com>
Sent: Wednesday, September 21, 2011 9:58 PM
Subject: Re: [volt-nuts] Eppley Standard Cell and What Is It?
John wrote:
>Some types of cells really do not
>like being inverted. It is designed to work into an open circuit.... ie:
>potentiometric comparison.
>From the Solartron 7081 specs I see its DCV input resistance is >10G ohms
for 0.1 thru 10 V ranges.
Have any of you Solartron 7081 users looked to see if there are reverse
switching transients present at its front DCV input jack while in its DCV
mode?
In the case of the HP 3458A, you can temporarily turn-off Auto-Zero, which,
I *think* should minimize if not eliminate any possible switching transients
present at its front DCV input terminals. By comparison I'm not sure how
this works with the Solartron 7081?
Disclaimer: I've not personally characterized any possible reverse switching
transients present at the 3458A input terminals. But, in theory I think I'd
temporarily turn-off Auto-Zero immediately prior to connecting to the
Eppley.
Admittedly the Eppley was originally designed to work into infinite load
resistance (potentiometric comparison back in the old days when DCV meter
input resistance was lower than for the 7081 and 3458A).
Comments?
Greg
_______________________________________________
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
G
gbusg
Thu, Sep 22, 2011 7:16 AM
Then again, in his document, Mr. Hoffman says, "This statement obviously
does not include solid state scanners meant for the purpose, or
"electrometer input" DVMs having input impedances of hundreds of megohms."
...So maybe 10G ohm input resistance DMMs are safe after all? ...Which maybe
leads us back to the question as to if their Auto-Zero (or other internal
functions) might generate reverse switching noise back into the Weston
Standard Cell? (I still would put the DMM in "Manual Range" and "Auto-Zero
Off" modes, just to be safe?)
...Apology for so many consecutive posts about this as I read further in
Conrad Hoffman's document.
-Greg
----- Original Message -----
From: "gbusg" gbusg@comcast.net
To: "Discussion of precise voltage measurement" volt-nuts@febo.com
Sent: Thursday, September 22, 2011 1:05 AM
Subject: Re: [volt-nuts] Eppley Standard Cell and What Is It?
P.S. Conrad Hoffman has good info on the topic of Weston saturated and
un-saturated standard cells.
According to his info, even high resistance input modern DMMs shouldn't be
used to directly measure the output of Weston standard cells.
See:
http://conradhoffman.com/stdcell.htm
Greg
----- Original Message -----
From: "gbusg" gbusg@comcast.net
To: jfor@quikus.com; "Discussion of precise voltage measurement"
volt-nuts@febo.com
Sent: Wednesday, September 21, 2011 9:58 PM
Subject: Re: [volt-nuts] Eppley Standard Cell and What Is It?
John wrote:
Some types of cells really do not
like being inverted. It is designed to work into an open circuit.... ie:
potentiometric comparison.
From the Solartron 7081 specs I see its DCV input resistance is >10G ohms
for 0.1 thru 10 V ranges.
Have any of you Solartron 7081 users looked to see if there are reverse
switching transients present at its front DCV input jack while in its DCV
mode?
In the case of the HP 3458A, you can temporarily turn-off Auto-Zero, which,
I think should minimize if not eliminate any possible switching transients
present at its front DCV input terminals. By comparison I'm not sure how
this works with the Solartron 7081?
Disclaimer: I've not personally characterized any possible reverse switching
transients present at the 3458A input terminals. But, in theory I think I'd
temporarily turn-off Auto-Zero immediately prior to connecting to the
Eppley.
Admittedly the Eppley was originally designed to work into infinite load
resistance (potentiometric comparison back in the old days when DCV meter
input resistance was lower than for the 7081 and 3458A).
Comments?
Greg
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
Then again, in his document, Mr. Hoffman says, "This statement obviously
does not include solid state scanners meant for the purpose, or
"electrometer input" DVMs having input impedances of hundreds of megohms."
...So maybe 10G ohm input resistance DMMs are safe after all? ...Which maybe
leads us back to the question as to if their Auto-Zero (or other internal
functions) might generate reverse switching noise back into the Weston
Standard Cell? (I still would put the DMM in "Manual Range" and "Auto-Zero
Off" modes, just to be safe?)
...Apology for so many consecutive posts about this as I read further in
Conrad Hoffman's document.
-Greg
----- Original Message -----
From: "gbusg" <gbusg@comcast.net>
To: "Discussion of precise voltage measurement" <volt-nuts@febo.com>
Sent: Thursday, September 22, 2011 1:05 AM
Subject: Re: [volt-nuts] Eppley Standard Cell and What Is It?
P.S. Conrad Hoffman has good info on the topic of Weston saturated and
un-saturated standard cells.
According to his info, even high resistance input modern DMMs shouldn't be
used to directly measure the output of Weston standard cells.
See:
http://conradhoffman.com/stdcell.htm
Greg
----- Original Message -----
From: "gbusg" <gbusg@comcast.net>
To: <jfor@quikus.com>; "Discussion of precise voltage measurement"
<volt-nuts@febo.com>
Sent: Wednesday, September 21, 2011 9:58 PM
Subject: Re: [volt-nuts] Eppley Standard Cell and What Is It?
John wrote:
>Some types of cells really do not
>like being inverted. It is designed to work into an open circuit.... ie:
>potentiometric comparison.
>From the Solartron 7081 specs I see its DCV input resistance is >10G ohms
for 0.1 thru 10 V ranges.
Have any of you Solartron 7081 users looked to see if there are reverse
switching transients present at its front DCV input jack while in its DCV
mode?
In the case of the HP 3458A, you can temporarily turn-off Auto-Zero, which,
I *think* should minimize if not eliminate any possible switching transients
present at its front DCV input terminals. By comparison I'm not sure how
this works with the Solartron 7081?
Disclaimer: I've not personally characterized any possible reverse switching
transients present at the 3458A input terminals. But, in theory I think I'd
temporarily turn-off Auto-Zero immediately prior to connecting to the
Eppley.
Admittedly the Eppley was originally designed to work into infinite load
resistance (potentiometric comparison back in the old days when DCV meter
input resistance was lower than for the 7081 and 3458A).
Comments?
Greg
_______________________________________________
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
_______________________________________________
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
FS
Fred Schneider
Thu, Sep 22, 2011 7:40 AM
Nice info. I made a C program to calculate the voltage, took me a while, now I see he allready made one.
I have a paper downloaded from NIST about the history of standard cells, very good stuff.
I measure my cells with the meter in manual 1V range. The meters I use for that are > 10 GOhm. I have a bridge, null detector ect but I think it is more safe to measure direct. ( i store the value in my solartron as calibration for the 1 V range, then use the 720, 845 and 332 to set the 332 at 10 V and calibrte the solartron with that. After that I use the solartron as monitor for the 332 to calibrate an other meter) It takes shorter time totrouble the cells, no chance in connecting someting wrong and safer because a potentiometric setup does not draw current, if both sources are equal, but they are not at the start of the measurement.
I have the history of my cells from new but a gap of about 20 years were they were not used ( but not heated, not calibrated but also and not moved from the lab they were in use)
I measured them ith a brand new 2000 but later found out I have to include he uncertanty from the 2000, the fact the oven is not nulled and the rather big tempco. The meaurement-limmits are so, the cells could still have their original value.
Would it be realistic to follow the trend line from 1973 to 1988 and use that value as a reference, corrected for temperature. ( i know the calibration temps) that will fall within the 2000 measured range. The cells are still spaced in voltage excact as they were in 1988.
Fred PA4TIM
Op 22 sep. 2011 om 09:16 heeft "gbusg" gbusg@comcast.net het volgende geschreven:
Then again, in his document, Mr. Hoffman says, "This statement obviously
does not include solid state scanners meant for the purpose, or
"electrometer input" DVMs having input impedances of hundreds of megohms."
...So maybe 10G ohm input resistance DMMs are safe after all? ...Which maybe
leads us back to the question as to if their Auto-Zero (or other internal
functions) might generate reverse switching noise back into the Weston
Standard Cell? (I still would put the DMM in "Manual Range" and "Auto-Zero
Off" modes, just to be safe?)
...Apology for so many consecutive posts about this as I read further in
Conrad Hoffman's document.
-Greg
----- Original Message -----
From: "gbusg" gbusg@comcast.net
To: "Discussion of precise voltage measurement" volt-nuts@febo.com
Sent: Thursday, September 22, 2011 1:05 AM
Subject: Re: [volt-nuts] Eppley Standard Cell and What Is It?
P.S. Conrad Hoffman has good info on the topic of Weston saturated and
un-saturated standard cells.
According to his info, even high resistance input modern DMMs shouldn't be
used to directly measure the output of Weston standard cells.
See:
http://conradhoffman.com/stdcell.htm
Greg
----- Original Message -----
From: "gbusg" gbusg@comcast.net
To: jfor@quikus.com; "Discussion of precise voltage measurement"
volt-nuts@febo.com
Sent: Wednesday, September 21, 2011 9:58 PM
Subject: Re: [volt-nuts] Eppley Standard Cell and What Is It?
John wrote:
Some types of cells really do not
like being inverted. It is designed to work into an open circuit.... ie:
potentiometric comparison.
From the Solartron 7081 specs I see its DCV input resistance is >10G ohms
for 0.1 thru 10 V ranges.
Have any of you Solartron 7081 users looked to see if there are reverse
switching transients present at its front DCV input jack while in its DCV
mode?
In the case of the HP 3458A, you can temporarily turn-off Auto-Zero, which,
I think should minimize if not eliminate any possible switching transients
present at its front DCV input terminals. By comparison I'm not sure how
this works with the Solartron 7081?
Disclaimer: I've not personally characterized any possible reverse switching
transients present at the 3458A input terminals. But, in theory I think I'd
temporarily turn-off Auto-Zero immediately prior to connecting to the
Eppley.
Admittedly the Eppley was originally designed to work into infinite load
resistance (potentiometric comparison back in the old days when DCV meter
input resistance was lower than for the 7081 and 3458A).
Comments?
Greg
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Nice info. I made a C program to calculate the voltage, took me a while, now I see he allready made one.
I have a paper downloaded from NIST about the history of standard cells, very good stuff.
I measure my cells with the meter in manual 1V range. The meters I use for that are > 10 GOhm. I have a bridge, null detector ect but I think it is more safe to measure direct. ( i store the value in my solartron as calibration for the 1 V range, then use the 720, 845 and 332 to set the 332 at 10 V and calibrte the solartron with that. After that I use the solartron as monitor for the 332 to calibrate an other meter) It takes shorter time totrouble the cells, no chance in connecting someting wrong and safer because a potentiometric setup does not draw current, if both sources are equal, but they are not at the start of the measurement.
I have the history of my cells from new but a gap of about 20 years were they were not used ( but not heated, not calibrated but also and not moved from the lab they were in use)
I measured them ith a brand new 2000 but later found out I have to include he uncertanty from the 2000, the fact the oven is not nulled and the rather big tempco. The meaurement-limmits are so, the cells could still have their original value.
Would it be realistic to follow the trend line from 1973 to 1988 and use that value as a reference, corrected for temperature. ( i know the calibration temps) that will fall within the 2000 measured range. The cells are still spaced in voltage excact as they were in 1988.
Fred PA4TIM
Op 22 sep. 2011 om 09:16 heeft "gbusg" <gbusg@comcast.net> het volgende geschreven:
> Then again, in his document, Mr. Hoffman says, "This statement obviously
> does not include solid state scanners meant for the purpose, or
> "electrometer input" DVMs having input impedances of hundreds of megohms."
> ...So maybe 10G ohm input resistance DMMs are safe after all? ...Which maybe
> leads us back to the question as to if their Auto-Zero (or other internal
> functions) might generate reverse switching noise back into the Weston
> Standard Cell? (I still would put the DMM in "Manual Range" and "Auto-Zero
> Off" modes, just to be safe?)
>
> ...Apology for so many consecutive posts about this as I read further in
> Conrad Hoffman's document.
>
> -Greg
>
>
> ----- Original Message -----
> From: "gbusg" <gbusg@comcast.net>
> To: "Discussion of precise voltage measurement" <volt-nuts@febo.com>
> Sent: Thursday, September 22, 2011 1:05 AM
> Subject: Re: [volt-nuts] Eppley Standard Cell and What Is It?
>
>
> P.S. Conrad Hoffman has good info on the topic of Weston saturated and
> un-saturated standard cells.
>
> According to his info, even high resistance input modern DMMs shouldn't be
> used to directly measure the output of Weston standard cells.
>
> See:
> http://conradhoffman.com/stdcell.htm
>
> Greg
>
>
> ----- Original Message -----
> From: "gbusg" <gbusg@comcast.net>
> To: <jfor@quikus.com>; "Discussion of precise voltage measurement"
> <volt-nuts@febo.com>
> Sent: Wednesday, September 21, 2011 9:58 PM
> Subject: Re: [volt-nuts] Eppley Standard Cell and What Is It?
>
>
> John wrote:
>> Some types of cells really do not
>> like being inverted. It is designed to work into an open circuit.... ie:
>> potentiometric comparison.
>
> From the Solartron 7081 specs I see its DCV input resistance is >10G ohms
> for 0.1 thru 10 V ranges.
>
> Have any of you Solartron 7081 users looked to see if there are reverse
> switching transients present at its front DCV input jack while in its DCV
> mode?
>
> In the case of the HP 3458A, you can temporarily turn-off Auto-Zero, which,
> I *think* should minimize if not eliminate any possible switching transients
> present at its front DCV input terminals. By comparison I'm not sure how
> this works with the Solartron 7081?
>
> Disclaimer: I've not personally characterized any possible reverse switching
> transients present at the 3458A input terminals. But, in theory I think I'd
> temporarily turn-off Auto-Zero immediately prior to connecting to the
> Eppley.
>
> Admittedly the Eppley was originally designed to work into infinite load
> resistance (potentiometric comparison back in the old days when DCV meter
> input resistance was lower than for the 7081 and 3458A).
>
> Comments?
>
> Greg
> _______________________________________________
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> and follow the instructions there.
>
>
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> and follow the instructions there.
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> and follow the instructions there.
RP
Roy Phillips
Thu, Sep 22, 2011 10:16 AM
Joe
Interesting point regarding the "Standard Cell", I have one that was
purchased some 12 years ago made by Western. It must be well beyond its
calibrated accuracy. It currently reads 1.018679 volts according to my
3458A. It seems to be stable but below its original labeled standard (label
lost). Are they worth keeping ?
Roy
From: "J. L. Trantham" jltran@att.net
Sent: Thursday, September 22, 2011 2:37 AM
To: "Discussion of precise voltage measurement" volt-nuts@febo.com
Subject: [volt-nuts] Eppley Standard Cell and What Is It?
I purchased an eBay item (190538109632) for the 'Standard Cell' that
included another item.
What is it?
The 'Standard Cell' is an 'Eppley Laboratory Catalog Number 100 (SN
762058) Low Termperature Coefficient Standard of E. M. F.' that has
written on it '1.01931 @ 20 degree C' with a date of what I think is
'2-4-69' which I think means Feburary 4, 1969.
Using my 'new' Solartron 7081, I read the voltage at 1.017844 +/- about 1
uV. If I have the math correct, that is a decrease of about 35 uV/yr
which, I think, is about what is predicted for these cell's, assuming my
7081 is accurate.
I also have another Eppley Standard Cell (SN 821855) that reads 1.018709
but no date or prior reading on the unit.
On another, unrelated note, I have been able to chase down the US branch
of Ametek in Oak Ridge, TN, and they will be getting my 7081 back to send
to England for calibration and 'service best effort', given that the meter
ceased production in 1998 with end of support 2008. TAT is about 4 weeks
in England.
Now, what is that other thing in the listing?
Joe
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and follow the instructions there.
Joe
Interesting point regarding the "Standard Cell", I have one that was
purchased some 12 years ago made by Western. It must be well beyond its
calibrated accuracy. It currently reads 1.018679 volts according to my
3458A. It seems to be stable but below its original labeled standard (label
lost). Are they worth keeping ?
Roy
--------------------------------------------------
From: "J. L. Trantham" <jltran@att.net>
Sent: Thursday, September 22, 2011 2:37 AM
To: "Discussion of precise voltage measurement" <volt-nuts@febo.com>
Subject: [volt-nuts] Eppley Standard Cell and What Is It?
> I purchased an eBay item (190538109632) for the 'Standard Cell' that
> included another item.
>
> What is it?
>
> The 'Standard Cell' is an 'Eppley Laboratory Catalog Number 100 (SN
> 762058) Low Termperature Coefficient Standard of E. M. F.' that has
> written on it '1.01931 @ 20 degree C' with a date of what I think is
> '2-4-69' which I think means Feburary 4, 1969.
>
> Using my 'new' Solartron 7081, I read the voltage at 1.017844 +/- about 1
> uV. If I have the math correct, that is a decrease of about 35 uV/yr
> which, I think, is about what is predicted for these cell's, assuming my
> 7081 is accurate.
>
> I also have another Eppley Standard Cell (SN 821855) that reads 1.018709
> but no date or prior reading on the unit.
>
> On another, unrelated note, I have been able to chase down the US branch
> of Ametek in Oak Ridge, TN, and they will be getting my 7081 back to send
> to England for calibration and 'service best effort', given that the meter
> ceased production in 1998 with end of support 2008. TAT is about 4 weeks
> in England.
>
> Now, what is that other thing in the listing?
>
> Joe
> _______________________________________________
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> and follow the instructions there.
>
JL
J. L. Trantham
Thu, Sep 22, 2011 12:54 PM
Roy,
The 'experts' are here on the list. From my reading, they have about a 50
uV/Yr expected decline in value, thus the need for periodic 'calibration'.
I do not have a feel for useful life expectancy but the two I have are in
good condition and only the latest one has a value on the front of '1.01931
@ 20 degrees C' with a date on the side of '2-4-69'. This AM, it measures
1.017894. However, the 7081 is not known to be accurate, yet.
The other cell still measures 1.018709 this AM.
So, it would appear that they will make a good standard but will need to be
measured from time to time to generate a log of date, temperature, and
value.
I wonder how long it has to be 'still' before it is again stable?
Joe
----- Original Message -----
From: "Roy Phillips" phill.r1@btinternet.com
To: "Discussion of precise voltage measurement" volt-nuts@febo.com
Sent: Thursday, September 22, 2011 5:16 AM
Subject: Re: [volt-nuts] Eppley Standard Cell and What Is It?
Joe
Interesting point regarding the "Standard Cell", I have one that was
purchased some 12 years ago made by Western. It must be well beyond its
calibrated accuracy. It currently reads 1.018679 volts according to my
3458A. It seems to be stable but below its original labeled standard
(label lost). Are they worth keeping ?
Roy
From: "J. L. Trantham" jltran@att.net
Sent: Thursday, September 22, 2011 2:37 AM
To: "Discussion of precise voltage measurement" volt-nuts@febo.com
Subject: [volt-nuts] Eppley Standard Cell and What Is It?
I purchased an eBay item (190538109632) for the 'Standard Cell' that
included another item.
What is it?
The 'Standard Cell' is an 'Eppley Laboratory Catalog Number 100 (SN
762058) Low Termperature Coefficient Standard of E. M. F.' that has
written on it '1.01931 @ 20 degree C' with a date of what I think is
'2-4-69' which I think means Feburary 4, 1969.
Using my 'new' Solartron 7081, I read the voltage at 1.017844 +/- about 1
uV. If I have the math correct, that is a decrease of about 35 uV/yr
which, I think, is about what is predicted for these cell's, assuming my
7081 is accurate.
I also have another Eppley Standard Cell (SN 821855) that reads 1.018709
but no date or prior reading on the unit.
On another, unrelated note, I have been able to chase down the US branch
of Ametek in Oak Ridge, TN, and they will be getting my 7081 back to send
to England for calibration and 'service best effort', given that the
meter ceased production in 1998 with end of support 2008. TAT is about 4
weeks in England.
Now, what is that other thing in the listing?
Joe
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
Roy,
The 'experts' are here on the list. From my reading, they have about a 50
uV/Yr expected decline in value, thus the need for periodic 'calibration'.
I do not have a feel for useful life expectancy but the two I have are in
good condition and only the latest one has a value on the front of '1.01931
@ 20 degrees C' with a date on the side of '2-4-69'. This AM, it measures
1.017894. However, the 7081 is not known to be accurate, yet.
The other cell still measures 1.018709 this AM.
So, it would appear that they will make a good standard but will need to be
measured from time to time to generate a log of date, temperature, and
value.
I wonder how long it has to be 'still' before it is again stable?
Joe
----- Original Message -----
From: "Roy Phillips" <phill.r1@btinternet.com>
To: "Discussion of precise voltage measurement" <volt-nuts@febo.com>
Sent: Thursday, September 22, 2011 5:16 AM
Subject: Re: [volt-nuts] Eppley Standard Cell and What Is It?
> Joe
> Interesting point regarding the "Standard Cell", I have one that was
> purchased some 12 years ago made by Western. It must be well beyond its
> calibrated accuracy. It currently reads 1.018679 volts according to my
> 3458A. It seems to be stable but below its original labeled standard
> (label lost). Are they worth keeping ?
> Roy
>
>
> --------------------------------------------------
> From: "J. L. Trantham" <jltran@att.net>
> Sent: Thursday, September 22, 2011 2:37 AM
> To: "Discussion of precise voltage measurement" <volt-nuts@febo.com>
> Subject: [volt-nuts] Eppley Standard Cell and What Is It?
>
>> I purchased an eBay item (190538109632) for the 'Standard Cell' that
>> included another item.
>>
>> What is it?
>>
>> The 'Standard Cell' is an 'Eppley Laboratory Catalog Number 100 (SN
>> 762058) Low Termperature Coefficient Standard of E. M. F.' that has
>> written on it '1.01931 @ 20 degree C' with a date of what I think is
>> '2-4-69' which I think means Feburary 4, 1969.
>>
>> Using my 'new' Solartron 7081, I read the voltage at 1.017844 +/- about 1
>> uV. If I have the math correct, that is a decrease of about 35 uV/yr
>> which, I think, is about what is predicted for these cell's, assuming my
>> 7081 is accurate.
>>
>> I also have another Eppley Standard Cell (SN 821855) that reads 1.018709
>> but no date or prior reading on the unit.
>>
>> On another, unrelated note, I have been able to chase down the US branch
>> of Ametek in Oak Ridge, TN, and they will be getting my 7081 back to send
>> to England for calibration and 'service best effort', given that the
>> meter ceased production in 1998 with end of support 2008. TAT is about 4
>> weeks in England.
>>
>> Now, what is that other thing in the listing?
>>
>> Joe
>> _______________________________________________
>> volt-nuts mailing list -- volt-nuts@febo.com
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
>> and follow the instructions there.
>>
>
>
> _______________________________________________
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> and follow the instructions there.
CH
Chuck Harris
Thu, Sep 22, 2011 1:32 PM
As I understand it, an unsaturated cell that measures 1.0178V is many, many years
past being useful as a standard, as is any unsaturated cell that measures below
1.0183V.
Saturated cells are very rare outside of laboratory conditions, as inverting the cell
will ruin it. Unsaturated cells can withstand the topsy turvy travel conditions
presented by shipping.
-Chuck Harris
J. L. Trantham wrote:
Roy,
The 'experts' are here on the list. From my reading, they have about a 50 uV/Yr
expected decline in value, thus the need for periodic 'calibration'. I do not have a
feel for useful life expectancy but the two I have are in good condition and only the
latest one has a value on the front of '1.01931 @ 20 degrees C' with a date on the
side of '2-4-69'. This AM, it measures 1.017894. However, the 7081 is not known to be
accurate, yet.
The other cell still measures 1.018709 this AM.
So, it would appear that they will make a good standard but will need to be measured
from time to time to generate a log of date, temperature, and value.
I wonder how long it has to be 'still' before it is again stable?
Joe
----- Original Message ----- From: "Roy Phillips" phill.r1@btinternet.com
To: "Discussion of precise voltage measurement" volt-nuts@febo.com
Sent: Thursday, September 22, 2011 5:16 AM
Subject: Re: [volt-nuts] Eppley Standard Cell and What Is It?
Joe
Interesting point regarding the "Standard Cell", I have one that was purchased some
12 years ago made by Western. It must be well beyond its calibrated accuracy. It
currently reads 1.018679 volts according to my 3458A. It seems to be stable but
below its original labeled standard (label lost). Are they worth keeping ?
Roy
From: "J. L. Trantham" jltran@att.net
Sent: Thursday, September 22, 2011 2:37 AM
To: "Discussion of precise voltage measurement" volt-nuts@febo.com
Subject: [volt-nuts] Eppley Standard Cell and What Is It?
I purchased an eBay item (190538109632) for the 'Standard Cell' that included
another item.
What is it?
The 'Standard Cell' is an 'Eppley Laboratory Catalog Number 100 (SN 762058) Low
Termperature Coefficient Standard of E. M. F.' that has written on it '1.01931 @
20 degree C' with a date of what I think is '2-4-69' which I think means Feburary
4, 1969.
Using my 'new' Solartron 7081, I read the voltage at 1.017844 +/- about 1 uV. If I
have the math correct, that is a decrease of about 35 uV/yr which, I think, is
about what is predicted for these cell's, assuming my 7081 is accurate.
I also have another Eppley Standard Cell (SN 821855) that reads 1.018709 but no
date or prior reading on the unit.
On another, unrelated note, I have been able to chase down the US branch of Ametek
in Oak Ridge, TN, and they will be getting my 7081 back to send to England for
calibration and 'service best effort', given that the meter ceased production in
1998 with end of support 2008. TAT is about 4 weeks in England.
Now, what is that other thing in the listing?
Joe
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
As I understand it, an unsaturated cell that measures 1.0178V is many, many years
past being useful as a standard, as is any unsaturated cell that measures below
1.0183V.
Saturated cells are very rare outside of laboratory conditions, as inverting the cell
will ruin it. Unsaturated cells can withstand the topsy turvy travel conditions
presented by shipping.
-Chuck Harris
J. L. Trantham wrote:
> Roy,
>
> The 'experts' are here on the list. From my reading, they have about a 50 uV/Yr
> expected decline in value, thus the need for periodic 'calibration'. I do not have a
> feel for useful life expectancy but the two I have are in good condition and only the
> latest one has a value on the front of '1.01931 @ 20 degrees C' with a date on the
> side of '2-4-69'. This AM, it measures 1.017894. However, the 7081 is not known to be
> accurate, yet.
>
> The other cell still measures 1.018709 this AM.
>
> So, it would appear that they will make a good standard but will need to be measured
> from time to time to generate a log of date, temperature, and value.
>
> I wonder how long it has to be 'still' before it is again stable?
>
> Joe
>
>
> ----- Original Message ----- From: "Roy Phillips" <phill.r1@btinternet.com>
> To: "Discussion of precise voltage measurement" <volt-nuts@febo.com>
> Sent: Thursday, September 22, 2011 5:16 AM
> Subject: Re: [volt-nuts] Eppley Standard Cell and What Is It?
>
>
>> Joe
>> Interesting point regarding the "Standard Cell", I have one that was purchased some
>> 12 years ago made by Western. It must be well beyond its calibrated accuracy. It
>> currently reads 1.018679 volts according to my 3458A. It seems to be stable but
>> below its original labeled standard (label lost). Are they worth keeping ?
>> Roy
>>
>>
>> --------------------------------------------------
>> From: "J. L. Trantham" <jltran@att.net>
>> Sent: Thursday, September 22, 2011 2:37 AM
>> To: "Discussion of precise voltage measurement" <volt-nuts@febo.com>
>> Subject: [volt-nuts] Eppley Standard Cell and What Is It?
>>
>>> I purchased an eBay item (190538109632) for the 'Standard Cell' that included
>>> another item.
>>>
>>> What is it?
>>>
>>> The 'Standard Cell' is an 'Eppley Laboratory Catalog Number 100 (SN 762058) Low
>>> Termperature Coefficient Standard of E. M. F.' that has written on it '1.01931 @
>>> 20 degree C' with a date of what I think is '2-4-69' which I think means Feburary
>>> 4, 1969.
>>>
>>> Using my 'new' Solartron 7081, I read the voltage at 1.017844 +/- about 1 uV. If I
>>> have the math correct, that is a decrease of about 35 uV/yr which, I think, is
>>> about what is predicted for these cell's, assuming my 7081 is accurate.
>>>
>>> I also have another Eppley Standard Cell (SN 821855) that reads 1.018709 but no
>>> date or prior reading on the unit.
>>>
>>> On another, unrelated note, I have been able to chase down the US branch of Ametek
>>> in Oak Ridge, TN, and they will be getting my 7081 back to send to England for
>>> calibration and 'service best effort', given that the meter ceased production in
>>> 1998 with end of support 2008. TAT is about 4 weeks in England.
>>>
>>> Now, what is that other thing in the listing?
>>>
>>> Joe
>>> _______________________________________________
>>> volt-nuts mailing list -- volt-nuts@febo.com
>>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
>>> and follow the instructions there.
>>>
>>
>>
>> _______________________________________________
>> volt-nuts mailing list -- volt-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
>> and follow the instructions there.
>
>
> _______________________________________________
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> and follow the instructions there.
>
