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Groups > sci.electronics.design > #429679 > unrolled thread

beads and zero ohm resistors

Started byJohn Larkin <jjlarkin@highlandtechnology.com>
First post2016-09-28 11:38 -0700
Last post2016-10-02 08:57 -0700
Articles 20 on this page of 30 — 13 participants

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Contents

  beads and zero ohm resistors John Larkin <jjlarkin@highlandtechnology.com> - 2016-09-28 11:38 -0700
    Re: beads and zero ohm resistors Cursitor Doom <curd@notformail.com> - 2016-09-28 18:59 +0000
      Re: beads and zero ohm resistors Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2016-09-28 12:57 -0700
        Re: beads and zero ohm resistors John Larkin <jjlarkin@highlandtechnology.com> - 2016-09-28 16:17 -0700
          Re: beads and zero ohm resistors John S <Sophi.2@invalid.org> - 2016-09-29 07:16 -0500
    Re: beads and zero ohm resistors boB <boB@theresnoplacelikehome.com> - 2016-09-28 14:11 -0700
      Re: beads and zero ohm resistors John Larkin <jjlarkin@highlandtechnology.com> - 2016-09-28 14:21 -0700
      Re: beads and zero ohm resistors Winfield Hill <hill@rowland.harvard.edu> - 2016-09-29 07:00 -0700
        Re: beads and zero ohm resistors boB <boB@theresnoplacelikehome.com> - 2016-09-29 13:59 -0700
          Re: beads and zero ohm resistors Winfield Hill <hill@rowland.harvard.edu> - 2016-09-29 14:21 -0700
            Re: beads and zero ohm resistors boB <boB@theresnoplacelikehome.com> - 2016-09-30 00:45 -0700
              Re: beads and zero ohm resistors "Tim Williams" <tiwill@seventransistorlabs.com> - 2016-09-30 22:18 -0500
                Re: beads and zero ohm resistors krw <krw@nowhere.com> - 2016-10-01 23:00 -0400
              Re: beads and zero ohm resistors krw <krw@nowhere.com> - 2016-10-01 22:58 -0400
    Re: beads and zero ohm resistors "Tim Williams" <tiwill@seventransistorlabs.com> - 2016-09-29 00:06 -0500
    Re: beads and zero ohm resistors dagmargoodboat@yahoo.com - 2016-09-29 06:16 -0700
      Re: beads and zero ohm resistors dagmargoodboat@yahoo.com - 2016-09-29 07:42 -0700
    Re: beads and zero ohm resistors George Herold <gherold@teachspin.com> - 2016-09-29 07:00 -0700
      Re: beads and zero ohm resistors dagmargoodboat@yahoo.com - 2016-09-29 07:46 -0700
        Re: beads and zero ohm resistors John Devereux <john@devereux.me.uk> - 2016-09-29 16:03 +0100
          Re: beads and zero ohm resistors George Herold <gherold@teachspin.com> - 2016-09-29 08:16 -0700
            Re: beads and zero ohm resistors dagmargoodboat@yahoo.com - 2016-09-29 09:02 -0700
          Re: beads and zero ohm resistors dagmargoodboat@yahoo.com - 2016-09-29 08:52 -0700
            Re: beads and zero ohm resistors John Devereux <john@devereux.me.uk> - 2016-09-29 16:56 +0100
              Re: beads and zero ohm resistors dagmargoodboat@yahoo.com - 2016-09-29 09:10 -0700
    Re: beads and zero ohm resistors Simon S Aysdie <gwhite@ti.com> - 2016-09-29 15:20 -0700
    Re: beads and zero ohm resistors John Larkin <jjlarkin@highlandtechnology.com> - 2016-09-29 20:14 -0700
    Re: beads and zero ohm resistors Robert Loos <1209@baer-gmbh.com> - 2016-09-30 11:40 +0200
      Re: beads and zero ohm resistors John Larkin <jjlarkin@highlandtechnology.com> - 2016-09-30 07:40 -0700
        Re: beads and zero ohm resistors Winfield Hill <hill@rowland.harvard.edu> - 2016-10-02 08:57 -0700

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#429679 — beads and zero ohm resistors

FromJohn Larkin <jjlarkin@highlandtechnology.com>
Date2016-09-28 11:38 -0700
Subjectbeads and zero ohm resistors
Message-ID<hb3oubh66n45tr3lfnc7s5im1plq8r72vt@4ax.com>

Has anyone measured the resistance and tempco of cheap surface-mount
zero-ohm resistors?

Has anyone measured the resistance tempco of surf-mount ferrite beads?

How are those constructed anyhow?

I guess I'll have to get out of my comfy chair and measure some.


-- 

John Larkin         Highland Technology, Inc
picosecond timing   precision measurement 

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

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#429686

FromCursitor Doom <curd@notformail.com>
Date2016-09-28 18:59 +0000
Message-ID<nsh3tl$go0$20@dont-email.me>
In reply to#429679
On Wed, 28 Sep 2016 11:38:10 -0700, John Larkin wrote:

> Has anyone measured the resistance and tempco of cheap surface-mount
> zero-ohm resistors?

Excuse my ignorance, but aren't these basically just jumpers - and used 
as such?

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#429692

FromJim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com>
Date2016-09-28 12:57 -0700
Message-ID<d48oubp903kdqeuvp7o9r9jm867208cmpf@4ax.com>
In reply to#429686
On Wed, 28 Sep 2016 18:59:01 -0000 (UTC), Cursitor Doom
<curd@notformail.com> wrote:

>On Wed, 28 Sep 2016 11:38:10 -0700, John Larkin wrote:
>
>> Has anyone measured the resistance and tempco of cheap surface-mount
>> zero-ohm resistors?
>
>Excuse my ignorance, but aren't these basically just jumpers - and used 
>as such?

Larkin isn't getting enough podium time... thus the stupid question
>:-}
		
                                        ...Jim Thompson
-- 
| James E.Thompson                                 |    mens     |
| Analog Innovations                               |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| STV, Queen Creek, AZ 85142    Skype: skypeanalog |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |

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#429721

FromJohn Larkin <jjlarkin@highlandtechnology.com>
Date2016-09-28 16:17 -0700
Message-ID<ijjoubd9etssl8decpn7lshpigb48672tl@4ax.com>
In reply to#429692
On Wed, 28 Sep 2016 12:57:36 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

>On Wed, 28 Sep 2016 18:59:01 -0000 (UTC), Cursitor Doom
><curd@notformail.com> wrote:
>
>>On Wed, 28 Sep 2016 11:38:10 -0700, John Larkin wrote:
>>
>>> Has anyone measured the resistance and tempco of cheap surface-mount
>>> zero-ohm resistors?
>>
>>Excuse my ignorance, but aren't these basically just jumpers - and used 
>>as such?
>
>Larkin isn't getting enough podium time... thus the stupid question
>>:-}
>		
>                                        ...Jim Thompson


This is an electronics discussion group. It will die if we don't
discuss electronics. Like, if all people like you post is home
woodworking problems and redneck political links.

And neither of my questions are stupid. Both could matter; right now,
to me, both do matter.


-- 

John Larkin         Highland Technology, Inc
picosecond timing   precision measurement 

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

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#429788

FromJohn S <Sophi.2@invalid.org>
Date2016-09-29 07:16 -0500
Message-ID<nsj0lm$cpu$1@dont-email.me>
In reply to#429721
On 9/28/2016 6:17 PM, John Larkin wrote:
> On Wed, 28 Sep 2016 12:57:36 -0700, Jim Thompson
> <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:
>
>> On Wed, 28 Sep 2016 18:59:01 -0000 (UTC), Cursitor Doom
>> <curd@notformail.com> wrote:
>>
>>> On Wed, 28 Sep 2016 11:38:10 -0700, John Larkin wrote:
>>>
>>>> Has anyone measured the resistance and tempco of cheap surface-mount
>>>> zero-ohm resistors?
>>>
>>> Excuse my ignorance, but aren't these basically just jumpers - and used
>>> as such?
>>
>> Larkin isn't getting enough podium time... thus the stupid question
>>> :-}
>> 		
>>                                        ...Jim Thompson
>
>
> This is an electronics discussion group. It will die if we don't
> discuss electronics. Like, if all people like you post is home
> woodworking problems and redneck political links.
>
> And neither of my questions are stupid. Both could matter; right now,
> to me, both do matter.

+1

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#429707

FromboB <boB@theresnoplacelikehome.com>
Date2016-09-28 14:11 -0700
Message-ID<1dcoublnsvh3kggeaqb149b12lt6baockd@4ax.com>
In reply to#429679
On Wed, 28 Sep 2016 11:38:10 -0700, John Larkin
<jjlarkin@highlandtechnology.com> wrote:

>
>
>Has anyone measured the resistance and tempco of cheap surface-mount
>zero-ohm resistors?
>
>Has anyone measured the resistance tempco of surf-mount ferrite beads?
>
>How are those constructed anyhow?
>
>I guess I'll have to get out of my comfy chair and measure some.


The spec sheets I've seen say around 20 milliOhms for the 0805 or 0603
zero Ohm resistors.

I have tended to shy away from using "zero" Ohm resistors as option
jumpers in PCBs because I find that they open up too often.

Need lower resistance than zero Ohms I guess.

boB

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#429708

FromJohn Larkin <jjlarkin@highlandtechnology.com>
Date2016-09-28 14:21 -0700
Message-ID<hrcoublp6d3cn46hn5831ld3ft290ucibu@4ax.com>
In reply to#429707
On Wed, 28 Sep 2016 14:11:18 -0700, boB
<boB@theresnoplacelikehome.com> wrote:

>On Wed, 28 Sep 2016 11:38:10 -0700, John Larkin
><jjlarkin@highlandtechnology.com> wrote:
>
>>
>>
>>Has anyone measured the resistance and tempco of cheap surface-mount
>>zero-ohm resistors?
>>
>>Has anyone measured the resistance tempco of surf-mount ferrite beads?
>>
>>How are those constructed anyhow?
>>
>>I guess I'll have to get out of my comfy chair and measure some.
>
>
>The spec sheets I've seen say around 20 milliOhms for the 0805 or 0603
>zero Ohm resistors.
>
>I have tended to shy away from using "zero" Ohm resistors as option
>jumpers in PCBs because I find that they open up too often.
>
>Need lower resistance than zero Ohms I guess.
>
>boB
>

I grabbed one of the generic 0r 0805 parts from our stock. I had to
run an amp through it to get enough resolution; it measures 5.75
milliohms.

A *very* rough temp test, with freeze spray, came up +3000 PPM/K,
which is consistant with most pure metals, which run around 4000.


-- 

John Larkin         Highland Technology, Inc
picosecond timing   precision measurement 

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

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#429802

FromWinfield Hill <hill@rowland.harvard.edu>
Date2016-09-29 07:00 -0700
Message-ID<nsj6qk01hni@drn.newsguy.com>
In reply to#429707
boB wrote...
>
> John Larkin wrote:
>
>> Has anyone measured the resistance and tempco
>> of cheap surface-mount zero-ohm resistors?
>
> The spec sheets I've seen say around 20 milliOhms
> for the 0805 or 0603 zero Ohm resistors.
>
> I have tended to shy away from using "zero"
> Ohm resistors as option jumpers in PCBs
> because I find that they open up too often.

 How much current does it take to make them blow?


-- 
 Thanks,
    - Win

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#429841

FromboB <boB@theresnoplacelikehome.com>
Date2016-09-29 13:59 -0700
Message-ID<7pvqubhhml1ap7tnom7kpegtkh1bs52bvl@4ax.com>
In reply to#429802
On 29 Sep 2016 07:00:52 -0700, Winfield Hill
<hill@rowland.harvard.edu> wrote:

>boB wrote...
>>
>> John Larkin wrote:
>>
>>> Has anyone measured the resistance and tempco
>>> of cheap surface-mount zero-ohm resistors?
>>
>> The spec sheets I've seen say around 20 milliOhms
>> for the 0805 or 0603 zero Ohm resistors.
>>
>> I have tended to shy away from using "zero"
>> Ohm resistors as option jumpers in PCBs
>> because I find that they open up too often.
>
> How much current does it take to make them blow?


I can't remember but it should be easy to test for.
I think our main problem was in the coil lead of a
relay.  I've seen them open up in other applications so
I try not to use them.  Typically I only use them for 
"options" on a PCB anyway.

Another thing regarding small-ish parts like these is
that, for all resistors, say less than a hundred Ohms,
should be "pulse rated"... meaning, they shiould at least
publish the overload specs for the resistors unless there is
just very very low current through them.  It's a rule my
company has adopted though.

It may be that the zero ohm resistors we have used
were not made by Vishay or Stackpole or one of those
companies that specify a decent maximum repetitive
pulse power.

This is especially important for gate drive resistors where
a capacitor is charged and discharged rapidly.

boB
K7IQ

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#429843

FromWinfield Hill <hill@rowland.harvard.edu>
Date2016-09-29 14:21 -0700
Message-ID<nsk0kd01en@drn.newsguy.com>
In reply to#429841
boB wrote...
>
> Another thing regarding small-ish parts like these is
> that, for all resistors, say less than a hundred Ohms,
> should be "pulse rated"... meaning, they shiould at least
> publish the overload specs for the resistors unless there is
> just very very low current through them.  It's a rule my
> company has adopted though.

 Ditto for SMT resistors with more than say 10V across
 them, and that might experience moderate power surges.

 My technician's front-loading washing machine control
 board (with elegant Analog Devices DSP six-IGBT three-
 phase VFD motor-drive controller) failed when an 0805
 resistor blew in the offline switching-supply circuit.

 My beautiful expensive Casablanca remote-controlled
 multi-speed reversible ceiling fan failed when an
 SMT resistor failed, similar story.

 And etc.


-- 
 Thanks,
    - Win

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#429878

FromboB <boB@theresnoplacelikehome.com>
Date2016-09-30 00:45 -0700
Message-ID<rm5subptrlcput4qt3ecp39spp91krq282@4ax.com>
In reply to#429843
On 29 Sep 2016 14:21:17 -0700, Winfield Hill
<hill@rowland.harvard.edu> wrote:

>boB wrote...
>>
>> Another thing regarding small-ish parts like these is
>> that, for all resistors, say less than a hundred Ohms,
>> should be "pulse rated"... meaning, they shiould at least
>> publish the overload specs for the resistors unless there is
>> just very very low current through them.  It's a rule my
>> company has adopted though.
>
> Ditto for SMT resistors with more than say 10V across
> them, and that might experience moderate power surges.
>
> My technician's front-loading washing machine control
> board (with elegant Analog Devices DSP six-IGBT three-
> phase VFD motor-drive controller) failed when an 0805
> resistor blew in the offline switching-supply circuit.
>
> My beautiful expensive Casablanca remote-controlled
> multi-speed reversible ceiling fan failed when an
> SMT resistor failed, similar story.
>
> And etc.


And SMT capacitors can crack, too.  For instance, try not
to place them next to the edge of a board... Place them such
that if the PCB is going to flex, the cap can flex the least.

SMT capacitor size seems to matter also,  Smaller is usually better
we find. 1206 is getting too big at times. At least for stiff ceramic
types like X7R.  Film is better maybe.

Then again, if you don't mind paying a bit more, there are these
semi-flexible SMT caps we heard about but would rather not spend
the extra money if possible.

All these things that are found out over time. We try to learn from
past mistakes and experiences but sometimes we have to learn again.

boB


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#430011

From"Tim Williams" <tiwill@seventransistorlabs.com>
Date2016-09-30 22:18 -0500
Message-ID<nsn9s2$f7h$1@dont-email.me>
In reply to#429878
"boB" <boB@theresnoplacelikehome.com> wrote in message 
news:rm5subptrlcput4qt3ecp39spp91krq282@4ax.com...
> And SMT capacitors can crack, too.  For instance, try not
> to place them next to the edge of a board... Place them such
> that if the PCB is going to flex, the cap can flex the least.
>
> SMT capacitor size seems to matter also,  Smaller is usually better
> we find. 1206 is getting too big at times. At least for stiff ceramic
> types like X7R.  Film is better maybe.

IPC recommends 1210 at the largest.  I'll use up to 1812 (or is there any 
1818ish?), but carefully.

> Then again, if you don't mind paying a bit more, there are these
> semi-flexible SMT caps we heard about but would rather not spend
> the extra money if possible.

They're not too expensive IIRC, being used in automotive quantities.

Tim

-- 
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: http://seventransistorlabs.com 

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#430127

Fromkrw <krw@nowhere.com>
Date2016-10-01 23:00 -0400
Message-ID<dvt0vbd3luafgepd1m6q32b67ijgra8e1a@4ax.com>
In reply to#430011
On Fri, 30 Sep 2016 22:18:18 -0500, "Tim Williams"
<tiwill@seventransistorlabs.com> wrote:

>"boB" <boB@theresnoplacelikehome.com> wrote in message 
>news:rm5subptrlcput4qt3ecp39spp91krq282@4ax.com...
>> And SMT capacitors can crack, too.  For instance, try not
>> to place them next to the edge of a board... Place them such
>> that if the PCB is going to flex, the cap can flex the least.
>>
>> SMT capacitor size seems to matter also,  Smaller is usually better
>> we find. 1206 is getting too big at times. At least for stiff ceramic
>> types like X7R.  Film is better maybe.
>
>IPC recommends 1210 at the largest.  I'll use up to 1812 (or is there any 
>1818ish?), but carefully.
>
>> Then again, if you don't mind paying a bit more, there are these
>> semi-flexible SMT caps we heard about but would rather not spend
>> the extra money if possible.
>
>They're not too expensive IIRC, being used in automotive quantities.

I just got a quote for a 1uF 25V cap for about a nickel.  I think it
was for a million a year but I'd have to check that.  I didn't have
too much time to look at it before I left yesterday.

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#430125

Fromkrw <krw@nowhere.com>
Date2016-10-01 22:58 -0400
Message-ID<9nt0vbt24pvfsaoapgd9ii3vrbchkc51kn@4ax.com>
In reply to#429878
On Fri, 30 Sep 2016 00:45:07 -0700, boB
<boB@theresnoplacelikehome.com> wrote:

>On 29 Sep 2016 14:21:17 -0700, Winfield Hill
><hill@rowland.harvard.edu> wrote:
>
>>boB wrote...
>>>
>>> Another thing regarding small-ish parts like these is
>>> that, for all resistors, say less than a hundred Ohms,
>>> should be "pulse rated"... meaning, they shiould at least
>>> publish the overload specs for the resistors unless there is
>>> just very very low current through them.  It's a rule my
>>> company has adopted though.
>>
>> Ditto for SMT resistors with more than say 10V across
>> them, and that might experience moderate power surges.
>>
>> My technician's front-loading washing machine control
>> board (with elegant Analog Devices DSP six-IGBT three-
>> phase VFD motor-drive controller) failed when an 0805
>> resistor blew in the offline switching-supply circuit.
>>
>> My beautiful expensive Casablanca remote-controlled
>> multi-speed reversible ceiling fan failed when an
>> SMT resistor failed, similar story.
>>
>> And etc.
>
>
>And SMT capacitors can crack, too.  For instance, try not
>to place them next to the edge of a board... Place them such
>that if the PCB is going to flex, the cap can flex the least.
>
>SMT capacitor size seems to matter also,  Smaller is usually better
>we find. 1206 is getting too big at times. At least for stiff ceramic
>types like X7R.  Film is better maybe.

There are X7Rs that are designed with some flex and others that are
designed to open, rather than short.
>
>Then again, if you don't mind paying a bit more, there are these
>semi-flexible SMT caps we heard about but would rather not spend
>the extra money if possible.

Yes, in X7Rs, too.  In some uses, we're required to put two caps in
series so in case one shorts the magic smoke doesn't ruin our day.
That's not cheap, either (4x the capacitor).
>
>All these things that are found out over time. We try to learn from
>past mistakes and experiences but sometimes we have to learn again.

That's how the above edicts come about, too.  Strike your thumb with a
hammer and you tend to learn a lesson.

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#429775

From"Tim Williams" <tiwill@seventransistorlabs.com>
Date2016-09-29 00:06 -0500
Message-ID<nsi7fm$82l$1@dont-email.me>
In reply to#429679
The resistors are just the usual lowish-tempco metal-filled enamel, 
slathered on thick without laser trimming.

Multilayer beads/coils are probably something like Cu/Ag/Pd, applied as a 
ceramic glaze formulation that bakes into mostly-solid metal on heating. 
Noble metal content is needed, otherwise the ferric iron (a required part of 
a _ferri_te) oxidizes it, destroying the contact.  Not to mention making the 
ferrite terrible (too much Fe(II) would probably crystallize as magnetite, 
which sucks).

Caps have the same construction, but they get away with semiprecious metals 
more effectively as they only have to carry displacement current.  The metal 
layers can be very thin indeed.

Tim

-- 
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: http://seventransistorlabs.com

"John Larkin" <jjlarkin@highlandtechnology.com> wrote in message 
news:hb3oubh66n45tr3lfnc7s5im1plq8r72vt@4ax.com...
>
>
> Has anyone measured the resistance and tempco of cheap surface-mount
> zero-ohm resistors?
>
> Has anyone measured the resistance tempco of surf-mount ferrite beads?
>
> How are those constructed anyhow?
>
> I guess I'll have to get out of my comfy chair and measure some.
>
>
> -- 
>
> John Larkin         Highland Technology, Inc
> picosecond timing   precision measurement
>
> jlarkin att highlandtechnology dott com
> http://www.highlandtechnology.com
> 

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#429795

Fromdagmargoodboat@yahoo.com
Date2016-09-29 06:16 -0700
Message-ID<51295f75-555f-41b3-994c-d8412b8362a3@googlegroups.com>
In reply to#429679
On Wednesday, September 28, 2016 at 2:38:21 PM UTC-4, John Larkin wrote:
> Has anyone measured the resistance and tempco of cheap surface-mount
> zero-ohm resistors?
> 
> Has anyone measured the resistance tempco of surf-mount ferrite beads?
> 
> How are those constructed anyhow?
> 
> I guess I'll have to get out of my comfy chair and measure some.
> 
> 
> -- 
> 
> John Larkin         Highland Technology, Inc
> picosecond timing   precision measurement 
> 
> jlarkin att highlandtechnology dott com
> http://www.highlandtechnology.com

I measured a bunch some years ago.  I couldn't find my notes, so I
re-measured a few:

 #1 0805  0.020 ohms
 #2 0603  0.0085
 #3 0808  0.0085
 #4 0603  0.0165

I was considering using them as non-critical current-sense resistors.

Cheers,
James Arthur

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#429808

Fromdagmargoodboat@yahoo.com
Date2016-09-29 07:42 -0700
Message-ID<e0ef90c6-f170-4ec2-90e5-a457f255748a@googlegroups.com>
In reply to#429795
On Thursday, September 29, 2016 at 9:17:02 AM UTC-4, dagmarg...@yahoo.com wrote:
> On Wednesday, September 28, 2016 at 2:38:21 PM UTC-4, John Larkin wrote:
> > Has anyone measured the resistance and tempco of cheap surface-mount
> > zero-ohm resistors?
> > 
> > Has anyone measured the resistance tempco of surf-mount ferrite beads?
> > 
> > How are those constructed anyhow?
> > 
> > I guess I'll have to get out of my comfy chair and measure some.
> > 
> > 
> > -- 
> > 
> > John Larkin         Highland Technology, Inc
> > picosecond timing   precision measurement 
> > 
> > jlarkin att highlandtechnology dott com
> > http://www.highlandtechnology.com
> 
> I measured a bunch some years ago.  I couldn't find my notes, so I
> re-measured a few:
> 
>  #1 0805  0.020 ohms
>  #2 0603  0.0085
>  #3 0805  0.0085
>  #4 0603  0.0165
> 
> I was considering using them as non-critical current-sense resistors.
> 
> Cheers,
> James Arthur

Ooops, s/#3 0808/#3 0805/

These are from separate reels, BTW.

Cheers,
James Arthur

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#429801

FromGeorge Herold <gherold@teachspin.com>
Date2016-09-29 07:00 -0700
Message-ID<93def8a4-8ab6-4280-ab36-8b27de4ea314@googlegroups.com>
In reply to#429679
On Wednesday, September 28, 2016 at 2:38:21 PM UTC-4, John Larkin wrote:
> Has anyone measured the resistance and tempco of cheap surface-mount
> zero-ohm resistors?
> 
> Has anyone measured the resistance tempco of surf-mount ferrite beads?
> 
> How are those constructed anyhow?
I'm still hoping you'll take a grinder to one and see what's inside.  
(The FB's)  
Well and post pictures too.  

I'm using some of these..
http://www.digikey.com/product-detail/en/laird-signal-integrity-products/28C0236-0EW-10/240-2492-ND/806595

George H. 
> 
> I guess I'll have to get out of my comfy chair and measure some.
> 
> 
> -- 
> 
> John Larkin         Highland Technology, Inc
> picosecond timing   precision measurement 
> 
> jlarkin att highlandtechnology dott com
> http://www.highlandtechnology.com

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#429809

Fromdagmargoodboat@yahoo.com
Date2016-09-29 07:46 -0700
Message-ID<8bb2696f-75f5-4d18-98ea-4c50fcf1818c@googlegroups.com>
In reply to#429801
On Thursday, September 29, 2016 at 10:01:14 AM UTC-4, George Herold wrote:
> On Wednesday, September 28, 2016 at 2:38:21 PM UTC-4, John Larkin wrote:
> > Has anyone measured the resistance and tempco of cheap surface-mount
> > zero-ohm resistors?
> > 
> > Has anyone measured the resistance tempco of surf-mount ferrite beads?
> > 
> > How are those constructed anyhow?
> I'm still hoping you'll take a grinder to one and see what's inside.  
> (The FB's)  
> Well and post pictures too.  
> 
> I'm using some of these..
> http://www.digikey.com/product-detail/en/laird-signal-integrity-products/28C0236-0EW-10/240-2492-ND/806595
> 
> George H. 

If you whack an SMD F.B. with a hammer, I've only ever found an
alloy strap inside.

Cheers,
James Arthur

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#429812

FromJohn Devereux <john@devereux.me.uk>
Date2016-09-29 16:03 +0100
Message-ID<87twcykatr.fsf@devereux.me.uk>
In reply to#429809
dagmargoodboat@yahoo.com writes:

> On Thursday, September 29, 2016 at 10:01:14 AM UTC-4, George Herold wrote:
>> On Wednesday, September 28, 2016 at 2:38:21 PM UTC-4, John Larkin wrote:
>> > Has anyone measured the resistance and tempco of cheap surface-mount
>> > zero-ohm resistors?
>> > 
>> > Has anyone measured the resistance tempco of surf-mount ferrite beads?
>> > 
>> > How are those constructed anyhow?
>> I'm still hoping you'll take a grinder to one and see what's inside.  
>> (The FB's)  
>> Well and post pictures too.  
>> 
>> I'm using some of these..
>> http://www.digikey.com/product-detail/en/laird-signal-integrity-products/28C0236-0EW-10/240-2492-ND/806595
>> 
>> George H. 
>
> If you whack an SMD F.B. with a hammer, I've only ever found an
> alloy strap inside.

https://www.google.com/search?tbm=isch&q=chip+bead+structure


-- 

John Devereux

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