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beads and zero ohm resistors

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  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

Page 2 of 2 — ← Prev page 1 [2]

#429813

On Thursday, September 29, 2016 at 11:03:15 AM UTC-4, John Devereux wrote:
> 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

Nice,  thanks John 

George h. 

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#429818

On Thursday, September 29, 2016 at 11:17:06 AM UTC-4, George Herold wrote:
> On Thursday, September 29, 2016 at 11:03:15 AM UTC-4, John Devereux wrote:
> > 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
> 
> Nice,  thanks John 
> 
> George h.

These are the sorts I was thinking of:

http://katalog.we-online.de/media/images/v2/Family_WE-PBF.jpg

I'd forgotten all about the newer "chip" styles.

Cheers,
James

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#429815

On Thursday, September 29, 2016 at 11:03:15 AM UTC-4, John Devereux wrote:
> 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

That is nice, thanks.  I guess I need to whack them more often--the
last one was a decade or two ago.

Cheers,
James Arthur

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#429816

dagmargoodboat@yahoo.com writes:

> On Thursday, September 29, 2016 at 11:03:15 AM UTC-4, John Devereux wrote:
>> 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
>
> That is nice, thanks.  I guess I need to whack them more often--the
> last one was a decade or two ago.

Perhaps the higher current / lower Z types would tend towards your alloy
strap model.


-- 

John Devereux

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#429819

On Thursday, September 29, 2016 at 11:56:16 AM UTC-4, John Devereux wrote:
> dagmargoodboat@yahoo.com writes:
> 
> > On Thursday, September 29, 2016 at 11:03:15 AM UTC-4, John Devereux wrote:
> >> 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
> >
> > That is nice, thanks.  I guess I need to whack them more often--the
> > last one was a decade or two ago.
> 
> Perhaps the higher current / lower Z types would tend towards your alloy
> strap model.
> 
> 
> -- 
> 
> John Devereux

The end of this unit's left terminal looks like a plated copper strap:
http://media.digikey.com/Photos/Wurth%20Electronics%20Photos/7427930.jpg

But it looks almost like that guy's strap was inserted into a completed
ferrite bead, then bent; the ferrite units in my stock look like the
ferrite was formed in place around the strap.  No seams.

Cheers,
James Arthur

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#429846

On Wednesday, September 28, 2016 at 11:38:21 AM UTC-7, 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.

My reply here does not answer your question.  However, given the more general topic of "0 ohm resistors," I want to pass on some that I found.

http://www.rohm.com/web/in/datasheet/PMR50HZPJ000

An 0402 is less than 0.5 milli-Ohm and takes 20 A.

They are not inexpensive (cheap), especially the 0402.  

I found some parts from Stackpole that I thought were "equivalent," but the more I looked at them, I thought the metallic Rohm might be different in important ways.

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#429867

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.

As noted, I measured a cheap 0805 0r resistor and got around 6
milliohms with a positive TC around 3000 PPM/K.

One of my guys measured a ferrite bead:

https://dl.dropboxusercontent.com/u/53724080/Parts/Inductors/FB_1631008.txt

https://dl.dropboxusercontent.com/u/53724080/Parts/Inductors/FB_1631008.jpg

https://dl.dropboxusercontent.com/u/53724080/Parts/Inductors/FB_Cross.jpg


The background is that we are first-article testing a new resistor/RTD
simulator box. The 5-to-50 ohm range was expected to have a positive
tempco from some range-switching SSRs, and there's software correction
for that, but the measured tempco is almost twice the expected value.
I wanted to just frob the correction factor, but some people wanted to
understand why. Turns out that about half the error is in PCB traces
and the other half is in the ferrite bead. We could replace the bead
with a zero-ohm jumper, but we may as well leave it in (EMI
garlic-vampire mode) and correct for everything.


-- 

John Larkin         Highland Technology, Inc

lunatic fringe electronics 

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#429884

Hello John,
...
> Has anyone measured the resistance tempco of surf-mount ferrite beads?
No.
>
> How are those constructed anyhow?

Have a look at the video and the pics here:
http://www.we-online.de/web/en/electronic_components/produkte_pb/we-mpsb~1.php
to get an idea. I don't now how the produce the helix and how they fill 
the gaps with ferrite.
Some are at least produced as multilayer components, just like you would 
build a multilayer transformer coil or antenne on a PCB.

Cheers

Robert

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#429903

On Fri, 30 Sep 2016 11:40:20 +0200, Robert Loos <1209@baer-gmbh.com>
wrote:

>Hello John,
>...
>> Has anyone measured the resistance tempco of surf-mount ferrite beads?
>No.
>>
>> How are those constructed anyhow?
>
>Have a look at the video and the pics here:
>http://www.we-online.de/web/en/electronic_components/produkte_pb/we-mpsb~1.php
>to get an idea. I don't now how the produce the helix and how they fill 
>the gaps with ferrite.
>Some are at least produced as multilayer components, just like you would 
>build a multilayer transformer coil or antenne on a PCB.
>
>Cheers
>
>Robert

That's a really slick video. At the end, Youtube popped up pics of
Hillary and Milo. Milo, the Dangerous Faggot, is brilliant and
hilarious.

I don't think we've had any beads fail from capacitive charge inrush,
but I guess it might happen if there were giant electrolytics
downstream.

 
-- 

John Larkin         Highland Technology, Inc

lunatic fringe electronics 

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#430145

John Larkin wrote...
>
>  I don't think we've had any beads fail from
> capacitive charge inrush, but I guess it might
> happen if there were giant electrolytics downstream.

 I have an inrush problem with some of my high-voltage
 pulser designs, which have electrolytics to deliver
 pulses up to 20A.  Large external capacitors are also
 allowed.  In my prototypes I hold off the HV until
 200ms after the low-V supplies settle.  This means
 the switching MOSFET must dissipate a substantial
 amount of energy, 1/2 C V^2, or up to 120J for the
 onboard caps, and much more for any outboard caps.


-- 
 Thanks,
    - Win

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