(Sorry if this is a repost but it didn't show up on my end, the other day)

0.1 ohm 0.01% resistors seem a bit thin on the ground, so I was thinking:

<https://www.digikey.com/en/products/detail/te-connectivity-passive-product/CPF0805B1R0E1/14006819>

And:

<https://www.digikey.com/en/products/detail/pomona-electronics/72918/1196334>

Idea is to take a square of copper-clad and Dremel a line down the
middle, mount the resistors, and then drill out holes and solder on the
banana jacks in the appropriate spots for a given piece of equipment's
terminals, and shove the sumbitch on there when needed.

I don't have any mount-able male bananas on hand yet but I experimented
with ten of the 1206 1 ohms in parallel as described, in theory the
tolerance improves by sqrt(n) where n = 10.

Verifying if it actually does pushes the limits of my available
equipment but my recently-calibrated 3478A in the 4 wire connection,
after the copper-clad is thoroughly scrubbed clean before clipping the
leads and after the HP warms up for a half-hour and settles down, seems
to be telling me the resulting R is probably good enough for 0.03% rock
and roll:

<https://imgur.com/a/tFwbe8k>

But whether it's 0.0999, 0.1000, or 0.1001 this meter cannot decide.

Any construction tips for the next revision? the "prototype" is about an
inch on a side with the Rs about evenly spaced, and kinda crudely
solder-blobbed on each side bridging the gap but maybe it'd be better to
mount them some other way or make the board they're attached to bigger
or smaller

On Tuesday, 13 September 2022 at 16:13:22 UTC+1, bitrex wrote:

> I don't have any mount-able male bananas on hand yet but I experimented
> with ten of the 1206 1 ohms in parallel as described, in theory the
> tolerance improves by sqrt(n) where n = 10.

But only if the errors are random.

John

On Tuesday, September 13, 2022 at 10:36:37 AM UTC-7, John Walliker wrote:
> On Tuesday, 13 September 2022 at 16:13:22 UTC+1, bitrex wrote:

[about 0.1 ohm 0.01% sense resistors]
> > I don't have any mount-able male bananas on hand yet but I experimented
> > with ten of the 1206 1 ohms in parallel as described, in theory the
> > tolerance improves by sqrt(n) where n = 10.

> But only if the errors are random.

So, no improvement in temperature sensitivity nor aging, and...
you'd get better performance (drop the 0.1 ohm voltage drop)
sensing the magnetic field around a current-carrying wire.
Old-school, that'd be a flip coil.
Nowadays, Hall sensors and a thermostat, or maybe a fluxgate.

bitrex wrote:
> (Sorry if this is a repost but it didn't show up on my end, the other day)
>
> 0.1 ohm 0.01% resistors seem a bit thin on the ground, so I was thinking:
>
> <https://www.digikey.com/en/products/detail/te-connectivity-passive-product/CPF0805B1R0E1/14006819>
>
>
> And:
>
> <https://www.digikey.com/en/products/detail/pomona-electronics/72918/1196334>
>
>
> Idea is to take a square of copper-clad and Dremel a line down the
> middle, mount the resistors, and then drill out holes and solder on the
> banana jacks in the appropriate spots for a given piece of equipment's
> terminals, and shove the sumbitch on there when needed.
>
> I don't have any mount-able male bananas on hand yet but I experimented
> with ten of the 1206 1 ohms in parallel as described, in theory the
> tolerance improves by sqrt(n) where n = 10.
>
> Verifying if it actually does pushes the limits of my available
> equipment but my recently-calibrated 3478A in the 4 wire connection,
> after the copper-clad is thoroughly scrubbed clean before clipping the
> leads and after the HP warms up for a half-hour and settles down, seems
> to be telling me the resulting R is probably good enough for 0.03% rock
> and roll:
>
> <https://imgur.com/a/tFwbe8k>
>
> But whether it's 0.0999, 0.1000, or 0.1001 this meter cannot decide.
>
> Any construction tips for the next revision? the "prototype" is about an
> inch on a side with the Rs about evenly spaced, and kinda crudely
> solder-blobbed on each side bridging the gap but maybe it'd be better to
> mount them some other way or make the board they're attached to bigger
> or smaller
>

1-oz copper is 0.5 milliohms per square, so one square of copper at each
end will blow your error budget by a factor of 100.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

On Tue, 13 Sep 2022 11:13:13 -0400, bitrex <user@example.net> wrote:

>(Sorry if this is a repost but it didn't show up on my end, the other day)
>
>0.1 ohm 0.01% resistors seem a bit thin on the ground, so I was thinking:
>
><https://www.digikey.com/en/products/detail/te-connectivity-passive-product/CPF0805B1R0E1/14006819>
>
>And:
>
><https://www.digikey.com/en/products/detail/pomona-electronics/72918/1196334>
>
>Idea is to take a square of copper-clad and Dremel a line down the
>middle, mount the resistors, and then drill out holes and solder on the
>banana jacks in the appropriate spots for a given piece of equipment's
>terminals, and shove the sumbitch on there when needed.
>
>I don't have any mount-able male bananas on hand yet but I experimented
>with ten of the 1206 1 ohms in parallel as described, in theory the
>tolerance improves by sqrt(n) where n = 10.
>
>Verifying if it actually does pushes the limits of my available
>equipment but my recently-calibrated 3478A in the 4 wire connection,
>after the copper-clad is thoroughly scrubbed clean before clipping the
>leads and after the HP warms up for a half-hour and settles down, seems
>to be telling me the resulting R is probably good enough for 0.03% rock
>and roll:
>
><https://imgur.com/a/tFwbe8k>
>
>But whether it's 0.0999, 0.1000, or 0.1001 this meter cannot decide.
>
>Any construction tips for the next revision? the "prototype" is about an
>inch on a side with the Rs about evenly spaced, and kinda crudely
>solder-blobbed on each side bridging the gap but maybe it'd be better to
>mount them some other way or make the board they're attached to bigger
>or smaller

How much current?

1 oz copper is about 500 uohms/square, so be careful with that. You
might do some clever 4-wire sort of thing using both sides.

Post pics!

There are genuine manganin 4-wire resistors.

On Tuesday, 13 September 2022 at 20:18:11 UTC+1, John Larkin wrote:
> On Tue, 13 Sep 2022 11:13:13 -0400, bitrex <us...@example.net> wrote:
>
> >(Sorry if this is a repost but it didn't show up on my end, the other day)
> >
> >0.1 ohm 0.01% resistors seem a bit thin on the ground, so I was thinking:
> >
> ><https://www.digikey.com/en/products/detail/te-connectivity-passive-product/CPF0805B1R0E1/14006819>
> >
> >And:
> >
> ><https://www.digikey.com/en/products/detail/pomona-electronics/72918/1196334>
> >
> >Idea is to take a square of copper-clad and Dremel a line down the
> >middle, mount the resistors, and then drill out holes and solder on the
> >banana jacks in the appropriate spots for a given piece of equipment's
> >terminals, and shove the sumbitch on there when needed.
> >
> >I don't have any mount-able male bananas on hand yet but I experimented
> >with ten of the 1206 1 ohms in parallel as described, in theory the
> >tolerance improves by sqrt(n) where n = 10.
> >
> >Verifying if it actually does pushes the limits of my available
> >equipment but my recently-calibrated 3478A in the 4 wire connection,
> >after the copper-clad is thoroughly scrubbed clean before clipping the
> >leads and after the HP warms up for a half-hour and settles down, seems
> >to be telling me the resulting R is probably good enough for 0.03% rock
> >and roll:
> >
> ><https://imgur.com/a/tFwbe8k>
> >
> >But whether it's 0.0999, 0.1000, or 0.1001 this meter cannot decide.
> >
> >Any construction tips for the next revision? the "prototype" is about an
> >inch on a side with the Rs about evenly spaced, and kinda crudely
> >solder-blobbed on each side bridging the gap but maybe it'd be better to
> >mount them some other way or make the board they're attached to bigger
> >or smaller
> How much current?
>
> 1 oz copper is about 500 uohms/square, so be careful with that. You
> might do some clever 4-wire sort of thing using both sides.
>
> Post pics!
>
> There are genuine manganin 4-wire resistors.

I once visited the factory of an electricity meter manufacturer. They used
manganin shunts with thick copper terminals electron beam welded to
the ends so as to get a good 4-terminal connection.

John

On 9/13/2022 3:18 PM, John Larkin wrote:
> On Tue, 13 Sep 2022 11:13:13 -0400, bitrex <user@example.net> wrote:
>
>> (Sorry if this is a repost but it didn't show up on my end, the other day)
>>
>> 0.1 ohm 0.01% resistors seem a bit thin on the ground, so I was thinking:
>>
>> <https://www.digikey.com/en/products/detail/te-connectivity-passive-product/CPF0805B1R0E1/14006819>
>>
>> And:
>>
>> <https://www.digikey.com/en/products/detail/pomona-electronics/72918/1196334>
>>
>> Idea is to take a square of copper-clad and Dremel a line down the
>> middle, mount the resistors, and then drill out holes and solder on the
>> banana jacks in the appropriate spots for a given piece of equipment's
>> terminals, and shove the sumbitch on there when needed.
>>
>> I don't have any mount-able male bananas on hand yet but I experimented
>> with ten of the 1206 1 ohms in parallel as described, in theory the
>> tolerance improves by sqrt(n) where n = 10.
>>
>> Verifying if it actually does pushes the limits of my available
>> equipment but my recently-calibrated 3478A in the 4 wire connection,
>> after the copper-clad is thoroughly scrubbed clean before clipping the
>> leads and after the HP warms up for a half-hour and settles down, seems
>> to be telling me the resulting R is probably good enough for 0.03% rock
>> and roll:
>>
>> <https://imgur.com/a/tFwbe8k>
>>
>> But whether it's 0.0999, 0.1000, or 0.1001 this meter cannot decide.
>>
>> Any construction tips for the next revision? the "prototype" is about an
>> inch on a side with the Rs about evenly spaced, and kinda crudely
>> solder-blobbed on each side bridging the gap but maybe it'd be better to
>> mount them some other way or make the board they're attached to bigger
>> or smaller
>
> How much current?
>
> 1 oz copper is about 500 uohms/square, so be careful with that. You
> might do some clever 4-wire sort of thing using both sides.
>
> Post pics!
>
> There are genuine manganin 4-wire resistors.
>

Test

Sorry, my Usenet provider still seems to be dropping 75% of my replies
so further discussion on my part may be delayed :(

On 9/13/2022 3:18 PM, John Larkin wrote:
> On Tue, 13 Sep 2022 11:13:13 -0400, bitrex <user@example.net> wrote:
>
>> (Sorry if this is a repost but it didn't show up on my end, the other day)
>>
>> 0.1 ohm 0.01% resistors seem a bit thin on the ground, so I was thinking:
>>
>> <https://www.digikey.com/en/products/detail/te-connectivity-passive-product/CPF0805B1R0E1/14006819>
>>
>> And:
>>
>> <https://www.digikey.com/en/products/detail/pomona-electronics/72918/1196334>
>>
>> Idea is to take a square of copper-clad and Dremel a line down the
>> middle, mount the resistors, and then drill out holes and solder on the
>> banana jacks in the appropriate spots for a given piece of equipment's
>> terminals, and shove the sumbitch on there when needed.
>>
>> I don't have any mount-able male bananas on hand yet but I experimented
>> with ten of the 1206 1 ohms in parallel as described, in theory the
>> tolerance improves by sqrt(n) where n = 10.
>>
>> Verifying if it actually does pushes the limits of my available
>> equipment but my recently-calibrated 3478A in the 4 wire connection,
>> after the copper-clad is thoroughly scrubbed clean before clipping the
>> leads and after the HP warms up for a half-hour and settles down, seems
>> to be telling me the resulting R is probably good enough for 0.03% rock
>> and roll:
>>
>> <https://imgur.com/a/tFwbe8k>
>>
>> But whether it's 0.0999, 0.1000, or 0.1001 this meter cannot decide.
>>
>> Any construction tips for the next revision? the "prototype" is about an
>> inch on a side with the Rs about evenly spaced, and kinda crudely
>> solder-blobbed on each side bridging the gap but maybe it'd be better to
>> mount them some other way or make the board they're attached to bigger
>> or smaller
>
> How much current?
>
> 1 oz copper is about 500 uohms/square, so be careful with that. You
> might do some clever 4-wire sort of thing using both sides.
>
> Post pics!
>
> There are genuine manganin 4-wire resistors.
>

Calibrating the meter on gear like the Agilent 3631A, etc. so on the
fancy machines the calibration subroutine puts out a claimed 0.1 A and
something like 5.6 A, and asks you to enter the actual value by
measuring the drop across the shunt by measuring the voltage and
shifting the decimal point.

It knows if your shunt/connections are too far out from 0.1 and will
reject your input if it thinks it's BS.

> 1 oz copper is about 500 uohms/square, so be careful with that. You
> might do some clever 4-wire sort of thing using both sides.
>
> Post pics!

I'd like to take another shot at it once I get more resistors in.
Imagine a dog's dinner, tacking 1206 resistors across a gap on bare
copper-clad isn't so easy for me..

> There are genuine manganin 4-wire resistors.

I see resistance standards like these for sale, but how the hell would I
even connect them to the machine's terminals?

<https://www.ebay.com/itm/282726297541>

On Tue, 13 Sep 2022 12:57:11 -0700 (PDT), John Walliker
<jrwalliker@gmail.com> wrote:

>On Tuesday, 13 September 2022 at 20:18:11 UTC+1, John Larkin wrote:
>> On Tue, 13 Sep 2022 11:13:13 -0400, bitrex <us...@example.net> wrote:
>>
>> >(Sorry if this is a repost but it didn't show up on my end, the other day)
>> >
>> >0.1 ohm 0.01% resistors seem a bit thin on the ground, so I was thinking:
>> >
>> ><https://www.digikey.com/en/products/detail/te-connectivity-passive-product/CPF0805B1R0E1/14006819>
>> >
>> >And:
>> >
>> ><https://www.digikey.com/en/products/detail/pomona-electronics/72918/1196334>
>> >
>> >Idea is to take a square of copper-clad and Dremel a line down the
>> >middle, mount the resistors, and then drill out holes and solder on the
>> >banana jacks in the appropriate spots for a given piece of equipment's
>> >terminals, and shove the sumbitch on there when needed.
>> >
>> >I don't have any mount-able male bananas on hand yet but I experimented
>> >with ten of the 1206 1 ohms in parallel as described, in theory the
>> >tolerance improves by sqrt(n) where n = 10.
>> >
>> >Verifying if it actually does pushes the limits of my available
>> >equipment but my recently-calibrated 3478A in the 4 wire connection,
>> >after the copper-clad is thoroughly scrubbed clean before clipping the
>> >leads and after the HP warms up for a half-hour and settles down, seems
>> >to be telling me the resulting R is probably good enough for 0.03% rock
>> >and roll:
>> >
>> ><https://imgur.com/a/tFwbe8k>
>> >
>> >But whether it's 0.0999, 0.1000, or 0.1001 this meter cannot decide.
>> >
>> >Any construction tips for the next revision? the "prototype" is about an
>> >inch on a side with the Rs about evenly spaced, and kinda crudely
>> >solder-blobbed on each side bridging the gap but maybe it'd be better to
>> >mount them some other way or make the board they're attached to bigger
>> >or smaller
>> How much current?
>>
>> 1 oz copper is about 500 uohms/square, so be careful with that. You
>> might do some clever 4-wire sort of thing using both sides.
>>
>> Post pics!
>>
>> There are genuine manganin 4-wire resistors.
>
>I once visited the factory of an electricity meter manufacturer. They used
>manganin shunts with thick copper terminals electron beam welded to
>the ends so as to get a good 4-terminal connection.
>
>John

When we were in the NMR pulsed-gradient business, we made our own
current shunts.

https://www.dropbox.com/s/nlwbub0yx96krgl/Manganin_Bits.JPG?raw=1

We bought bulk manganin, had it rolled into sheets, punched it,
folded, and annealed. The planar shunts were epoxied to
constant-temperature aluminum blocks. We learned how to compensate
eddy-current effects to get PPM-flat pulse response.

DC shunts are easy!

On Tue, 13 Sep 2022 19:22:27 -0400, bitrex <user@example.net> wrote:

>On 9/13/2022 3:18 PM, John Larkin wrote:
>> On Tue, 13 Sep 2022 11:13:13 -0400, bitrex <user@example.net> wrote:
>>
>>> (Sorry if this is a repost but it didn't show up on my end, the other day)
>>>
>>> 0.1 ohm 0.01% resistors seem a bit thin on the ground, so I was thinking:
>>>
>>> <https://www.digikey.com/en/products/detail/te-connectivity-passive-product/CPF0805B1R0E1/14006819>
>>>
>>> And:
>>>
>>> <https://www.digikey.com/en/products/detail/pomona-electronics/72918/1196334>
>>>
>>> Idea is to take a square of copper-clad and Dremel a line down the
>>> middle, mount the resistors, and then drill out holes and solder on the
>>> banana jacks in the appropriate spots for a given piece of equipment's
>>> terminals, and shove the sumbitch on there when needed.
>>>
>>> I don't have any mount-able male bananas on hand yet but I experimented
>>> with ten of the 1206 1 ohms in parallel as described, in theory the
>>> tolerance improves by sqrt(n) where n = 10.
>>>
>>> Verifying if it actually does pushes the limits of my available
>>> equipment but my recently-calibrated 3478A in the 4 wire connection,
>>> after the copper-clad is thoroughly scrubbed clean before clipping the
>>> leads and after the HP warms up for a half-hour and settles down, seems
>>> to be telling me the resulting R is probably good enough for 0.03% rock
>>> and roll:
>>>
>>> <https://imgur.com/a/tFwbe8k>
>>>
>>> But whether it's 0.0999, 0.1000, or 0.1001 this meter cannot decide.
>>>
>>> Any construction tips for the next revision? the "prototype" is about an
>>> inch on a side with the Rs about evenly spaced, and kinda crudely
>>> solder-blobbed on each side bridging the gap but maybe it'd be better to
>>> mount them some other way or make the board they're attached to bigger
>>> or smaller
>>
>> How much current?
>>
>> 1 oz copper is about 500 uohms/square, so be careful with that. You
>> might do some clever 4-wire sort of thing using both sides.
>>
>> Post pics!
>>
>> There are genuine manganin 4-wire resistors.
>>
>
>
>
>Calibrating the meter on gear like the Agilent 3631A, etc. so on the
>fancy machines the calibration subroutine puts out a claimed 0.1 A and
>something like 5.6 A, and asks you to enter the actual value by
>measuring the drop across the shunt by measuring the voltage and
>shifting the decimal point.
>
>It knows if your shunt/connections are too far out from 0.1 and will
>reject your input if it thinks it's BS.
>
> > 1 oz copper is about 500 uohms/square, so be careful with that. You
> > might do some clever 4-wire sort of thing using both sides.
> >
> > Post pics!
>
>I'd like to take another shot at it once I get more resistors in.
>Imagine a dog's dinner, tacking 1206 resistors across a gap on bare
>copper-clad isn't so easy for me..

I use gold-plated copperclad. Solders magically.

https://www.dropbox.com/s/wgzr56dx43z14rp/Gold_FR4_3x.jpg?raw=1

https://www.dropbox.com/s/pa9mu4ehtrjei8m/Z384_1.JPG?raw=1

On a sunny day (Tue, 13 Sep 2022 20:00:32 -0700) it happened John Larkin
<jlarkin@highlandSNIPMEtechnology.com> wrote in
<24g2ih5l71m9mus1s657vmt230sprjaf14@4ax.com>:

>When we were in the NMR pulsed-gradient business, we made our own
>current shunts.
>
>https://www.dropbox.com/s/nlwbub0yx96krgl/Manganin_Bits.JPG?raw=1
>
>We bought bulk manganin, had it rolled into sheets, punched it,
>folded, and annealed. The planar shunts were epoxied to
>constant-temperature aluminum blocks. We learned how to compensate
>eddy-current effects to get PPM-flat pulse response.
>
>DC shunts are easy!

Yes, but I have some nice HALL effect current transducers HX03-P en HX10.

On Wed, 14 Sep 2022 05:30:54 GMT, Jan Panteltje
<pNaonStpealmtje@yahoo.com> wrote:

>On a sunny day (Tue, 13 Sep 2022 20:00:32 -0700) it happened John Larkin
><jlarkin@highlandSNIPMEtechnology.com> wrote in
><24g2ih5l71m9mus1s657vmt230sprjaf14@4ax.com>:
>
>>When we were in the NMR pulsed-gradient business, we made our own
>>current shunts.
>>
>>https://www.dropbox.com/s/nlwbub0yx96krgl/Manganin_Bits.JPG?raw=1
>>
>>We bought bulk manganin, had it rolled into sheets, punched it,
>>folded, and annealed. The planar shunts were epoxied to
>>constant-temperature aluminum blocks. We learned how to compensate
>>eddy-current effects to get PPM-flat pulse response.
>>
>>DC shunts are easy!
>
>Yes, but I have some nice HALL effect current transducers HX03-P en HX10.

We needed PPM flat and stable current pulses, which I suspect Hall
sensors can't do.