Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > sci.electronics.design > #450285 > unrolled thread

A useful addition to your toolkit

Back to article view | Back to sci.electronics.design

Contents

  A useful addition to your toolkit Cursitor Doom <curd@notformail.com> - 2017-03-05 14:48 +0000
    Re: A useful addition to your toolkit John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-05 07:44 -0800
      Re: A useful addition to your toolkit Cursitor Doom <curd@notformail.com> - 2017-03-05 16:18 +0000
        Re: A useful addition to your toolkit John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-05 09:28 -0800
          Re: A useful addition to your toolkit MJC <gravity@mjcoon.plus.com> - 2017-03-05 20:56 +0000
            Re: A useful addition to your toolkit Foxs Mercantile <jdangus@att.net> - 2017-03-05 15:07 -0600
              Re: A useful addition to your toolkit John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-05 13:37 -0800
                Re: A useful addition to your toolkit Foxs Mercantile <jdangus@att.net> - 2017-03-05 17:41 -0600
                  Re: A useful addition to your toolkit Winfield Hill <hill@rowland.harvard.edu> - 2017-03-05 16:35 -0800
                Re: A useful addition to your toolkit rickman <gnuarm@gmail.com> - 2017-03-06 00:58 -0500
                  Re: A useful addition to your toolkit Foxs Mercantile <jdangus@att.net> - 2017-03-06 00:56 -0600
                    Re: A useful addition to your toolkit rickman <gnuarm@gmail.com> - 2017-03-06 02:04 -0500
                    Re: A useful addition to your toolkit Cursitor Doom <curd@notformail.com> - 2017-03-06 11:27 +0000
                      Re: A useful addition to your toolkit "Michael A. Terrell" <mike.terrell@earthlink.net> - 2017-03-06 20:56 -0500
                        Re: A useful addition to your toolkit Cursitor Doom <curd@notformail.com> - 2017-03-07 18:16 +0000
                          Re: A useful addition to your toolkit Winfield Hill <hill@rowland.harvard.edu> - 2017-03-08 05:44 -0800
                            Re: A useful addition to your toolkit Cursitor Doom <curd@notformail.com> - 2017-03-08 14:52 +0000
                              Re: A useful addition to your toolkit Winfield Hill <hill@rowland.harvard.edu> - 2017-03-08 07:18 -0800
                            Re: A useful addition to your toolkit Jasen Betts <jasen@xnet.co.nz> - 2017-03-08 18:53 +0000
                              Re: A useful addition to your toolkit John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-03-08 16:05 -0800
                    Re: A useful addition to your toolkit John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-06 08:43 -0800
                      Re: A useful addition to your toolkit Winfield Hill <hill@rowland.harvard.edu> - 2017-03-06 18:06 -0800
                        Re: A useful addition to your toolkit "tom" <tmiller11147@verizon.net> - 2017-03-06 22:05 -0500
                        Re: A useful addition to your toolkit John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-06 20:56 -0800
                          Re: A useful addition to your toolkit Cursitor Doom <curd@notformail.com> - 2017-03-07 18:18 +0000
                Re: A useful addition to your toolkit "Tom Del Rosso" <fizzbintuesday@that-google-mail-domain.com> - 2017-03-11 16:31 -0500
          Re: A useful addition to your toolkit "Tom Del Rosso" <fizzbintuesday@that-google-mail-domain.com> - 2017-03-11 16:22 -0500
            Re: A useful addition to your toolkit dagmargoodboat@yahoo.com - 2017-03-11 17:49 -0800
              Re: A useful addition to your toolkit pcdhobbs@gmail.com - 2017-03-11 17:58 -0800
                Re: A useful addition to your toolkit dagmargoodboat@yahoo.com - 2017-03-11 19:07 -0800
                  Re: A useful addition to your toolkit pcdhobbs@gmail.com - 2017-03-11 20:14 -0800
      Re: A useful addition to your toolkit krw@notreal.com - 2017-03-05 19:41 -0500
        Re: A useful addition to your toolkit piglet <erichpwagner@hotmail.com> - 2017-03-06 11:01 +0000
      Re: A useful addition to your toolkit George Herold <gherold@teachspin.com> - 2017-03-05 17:43 -0800
        Re: A useful addition to your toolkit piglet <erichpwagner@hotmail.com> - 2017-03-06 10:28 +0000
          Re: A useful addition to your toolkit George Herold <gherold@teachspin.com> - 2017-03-06 05:47 -0800
            Re: A useful addition to your toolkit piglet <erichpwagner@hotmail.com> - 2017-03-06 14:08 +0000
              Re: A useful addition to your toolkit Sjouke Burry <burrynulnulfour@ppllaanneett.nnll> - 2017-03-06 15:34 +0100
                Re: A useful addition to your toolkit George Herold <gherold@teachspin.com> - 2017-03-06 07:26 -0800
              Re: A useful addition to your toolkit Ralph Barone <ralph@invalid.com> - 2017-03-06 15:41 +0000
                Re: A useful addition to your toolkit rickman <gnuarm@gmail.com> - 2017-03-06 23:04 -0500
              Re: A useful addition to your toolkit dagmargoodboat@yahoo.com - 2017-03-06 18:26 -0800
                Re: A useful addition to your toolkit John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-06 21:00 -0800
                  Re: A useful addition to your toolkit dagmargoodboat@yahoo.com - 2017-03-06 21:17 -0800
                    Re: A useful addition to your toolkit John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-06 21:36 -0800
                      Re: A useful addition to your toolkit Cursitor Doom <curd@notformail.com> - 2017-03-07 18:11 +0000
                        Re: A useful addition to your toolkit whit3rd <whit3rd@gmail.com> - 2017-03-07 14:03 -0800
                          Re: A useful addition to your toolkit Cursitor Doom <curd@notformail.com> - 2017-03-08 00:22 +0000
                          Re: A useful addition to your toolkit Bill Martin <wwm@wwmartin.net> - 2017-03-10 10:32 -0800
                    Re: A useful addition to your toolkit wolfgangfriedrich42@gmail.com - 2017-03-07 07:35 -0800
                      Re: A useful addition to your toolkit dagmargoodboat@yahoo.com - 2017-03-07 07:42 -0800
                      Re: A useful addition to your toolkit krw@notreal.com - 2017-03-07 20:56 -0500
                        Re: A useful addition to your toolkit Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-03-08 09:36 -0500
                          Re: A useful addition to your toolkit Winfield Hill <hill@rowland.harvard.edu> - 2017-03-08 07:21 -0800
                            Re: A useful addition to your toolkit wolfgangfriedrich42@gmail.com - 2017-03-08 09:00 -0800
                              Re: A useful addition to your toolkit krw@notreal.com - 2017-03-08 20:40 -0500
                            Re: A useful addition to your toolkit whit3rd <whit3rd@gmail.com> - 2017-03-09 16:24 -0800
                          Re: A useful addition to your toolkit krw@notreal.com - 2017-03-08 20:36 -0500
                Re: A useful addition to your toolkit George Herold <gherold@teachspin.com> - 2017-03-07 05:42 -0800
                  Re: A useful addition to your toolkit dagmargoodboat@yahoo.com - 2017-03-07 06:16 -0800
      Re: A useful addition to your toolkit JM <dontreplytothis173@gmail.com> - 2017-03-05 19:56 +0000
        Re: A useful addition to your toolkit John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-05 20:02 -0800
      Re: A useful addition to your toolkit Robert Baer <robertbaer@localnet.com> - 2017-03-09 22:43 -0800
        Re: A useful addition to your toolkit John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-03-10 10:04 -0800

Page 3 of 4 — ← Prev page 1 2 [3] 4  Next page →

#450572

On 3/6/2017 10:41 AM, Ralph Barone wrote:
> piglet <erichpwagner@hotmail.com> wrote:
>>
>> So imagine a pcb trace carrying the unknown load current. Place four
>> test probes in a line along that trace. Measure the voltage between the
>> inner pair and inject a current through the outer pair such that the
>> voltage measured is reduced to zero. The current you have to inject will
>> be the same magnitude but opposite direction to the unknown load current.
>>
>> piglet
>
> And how do you measure the injected current?
>
>  "You can't fool me!  It's turtles all the way down."

You can add a current sense resistor to that current... as large a 
turtle as you choose.  The idea is not not disrupt the measured current 
with a resistor.  Heck, this could be done with an external device like 
a meter.  You just need four probe points which wouldn't be too hard 
with a good design.  It would need to be sharp enough to pierce the 
solder mask easily.  The only danger to the electronics would be if you 
probed two different traces... lol

Maybe that should be one probe with four sharp contacts.

-- 

Rick C

[toc] | [prev] | [next] | [standalone]

#450560

On Monday, March 6, 2017 at 9:08:58 AM UTC-5, piglet wrote:
> On 06/03/2017 13:47, George Herold wrote:
> > On Monday, March 6, 2017 at 5:28:11 AM UTC-5, piglet wrote:
> >> If it's a kelvin connection to the pcb trace then you could neatly
> >> disregard the trace resistance by injecting a servo current to bring the
> >> IR drop to zero.
> >
> > Huh, push current back through the voltage leads of the Kelvin connection.
> > I drew that but now I've got all the current flowing through the voltage
> > leads... seems like I need yet another pair of leads.. A six wire "Kelvin"
> > connection.  Or I didn't draw it right.
> >
> > George H.
> >
> >>
> >> piglet
> >
> 
> So imagine a pcb trace carrying the unknown load current. Place four 
> test probes in a line along that trace. Measure the voltage between the 
> inner pair and inject a current through the outer pair such that the 
> voltage measured is reduced to zero. The current you have to inject will 
> be the same magnitude but opposite direction to the unknown load current.
> 
> piglet

You don't need to cancel the trace current--just injecting a calibrated
a.c. current between the two probes would be good enough to measure the
trace resistance, then compute the d.c. current from the d.c. drop.

Cheers,
James Arthur

[toc] | [prev] | [next] | [standalone]

#450581

On Mon, 6 Mar 2017 18:26:39 -0800 (PST), dagmargoodboat@yahoo.com
wrote:

>On Monday, March 6, 2017 at 9:08:58 AM UTC-5, piglet wrote:
>> On 06/03/2017 13:47, George Herold wrote:
>> > On Monday, March 6, 2017 at 5:28:11 AM UTC-5, piglet wrote:
>> >> If it's a kelvin connection to the pcb trace then you could neatly
>> >> disregard the trace resistance by injecting a servo current to bring the
>> >> IR drop to zero.
>> >
>> > Huh, push current back through the voltage leads of the Kelvin connection.
>> > I drew that but now I've got all the current flowing through the voltage
>> > leads... seems like I need yet another pair of leads.. A six wire "Kelvin"
>> > connection.  Or I didn't draw it right.
>> >
>> > George H.
>> >
>> >>
>> >> piglet
>> >
>> 
>> So imagine a pcb trace carrying the unknown load current. Place four 
>> test probes in a line along that trace. Measure the voltage between the 
>> inner pair and inject a current through the outer pair such that the 
>> voltage measured is reduced to zero. The current you have to inject will 
>> be the same magnitude but opposite direction to the unknown load current.
>> 
>> piglet
>
>You don't need to cancel the trace current--just injecting a calibrated
>a.c. current between the two probes would be good enough to measure the
>trace resistance, then compute the d.c. current from the d.c. drop.
>
>Cheers,
>James Arthur

Just power the board down and measure the trace resistance!

Another trick is to measure the drop in a trace, add a dummy load
resistor, note the delta-v, and do the math.

Or measure the trace resistance on a bare board from the same batch.


-- 

John Larkin         Highland Technology, Inc

lunatic fringe electronics 

[toc] | [prev] | [next] | [standalone]

#450583

On Tuesday, March 7, 2017 at 12:00:32 AM UTC-5, John Larkin wrote:
> On Mon, 6 Mar 2017 18:26:39 -0800 (PST), dagmargoodboat@yahoo.com
> wrote:
> 
> >On Monday, March 6, 2017 at 9:08:58 AM UTC-5, piglet wrote:
> >> On 06/03/2017 13:47, George Herold wrote:
> >> > On Monday, March 6, 2017 at 5:28:11 AM UTC-5, piglet wrote:
> >> >> If it's a kelvin connection to the pcb trace then you could neatly
> >> >> disregard the trace resistance by injecting a servo current to bring the
> >> >> IR drop to zero.
> >> >
> >> > Huh, push current back through the voltage leads of the Kelvin connection.
> >> > I drew that but now I've got all the current flowing through the voltage
> >> > leads... seems like I need yet another pair of leads.. A six wire "Kelvin"
> >> > connection.  Or I didn't draw it right.
> >> >
> >> > George H.
> >> >
> >> >>
> >> >> piglet
> >> >
> >> 
> >> So imagine a pcb trace carrying the unknown load current. Place four 
> >> test probes in a line along that trace. Measure the voltage between the 
> >> inner pair and inject a current through the outer pair such that the 
> >> voltage measured is reduced to zero. The current you have to inject will 
> >> be the same magnitude but opposite direction to the unknown load current.
> >> 
> >> piglet
> >
> >You don't need to cancel the trace current--just injecting a calibrated
> >a.c. current between the two probes would be good enough to measure the
> >trace resistance, then compute the d.c. current from the d.c. drop.
> >
> 
> Just power the board down and measure the trace resistance!

Sure, but we're talking an automated instrument do that all in one go,
without having to make a separate 4-wire resistance measurement.
 
> Another trick is to measure the drop in a trace, add a dummy load
> resistor, note the delta-v, and do the math.
>
> Or measure the trace resistance on a bare board from the same batch.

I like the magnetic probe for qualitative info.  Maybe a Hall probe
could do it too.

We need a FLIR for magnetic flux.

Cheers,
James Arthur

[toc] | [prev] | [next] | [standalone]

#450586

On Mon, 6 Mar 2017 21:17:32 -0800 (PST), dagmargoodboat@yahoo.com
wrote:

>On Tuesday, March 7, 2017 at 12:00:32 AM UTC-5, John Larkin wrote:
>> On Mon, 6 Mar 2017 18:26:39 -0800 (PST), dagmargoodboat@yahoo.com
>> wrote:
>> 
>> >On Monday, March 6, 2017 at 9:08:58 AM UTC-5, piglet wrote:
>> >> On 06/03/2017 13:47, George Herold wrote:
>> >> > On Monday, March 6, 2017 at 5:28:11 AM UTC-5, piglet wrote:
>> >> >> If it's a kelvin connection to the pcb trace then you could neatly
>> >> >> disregard the trace resistance by injecting a servo current to bring the
>> >> >> IR drop to zero.
>> >> >
>> >> > Huh, push current back through the voltage leads of the Kelvin connection.
>> >> > I drew that but now I've got all the current flowing through the voltage
>> >> > leads... seems like I need yet another pair of leads.. A six wire "Kelvin"
>> >> > connection.  Or I didn't draw it right.
>> >> >
>> >> > George H.
>> >> >
>> >> >>
>> >> >> piglet
>> >> >
>> >> 
>> >> So imagine a pcb trace carrying the unknown load current. Place four 
>> >> test probes in a line along that trace. Measure the voltage between the 
>> >> inner pair and inject a current through the outer pair such that the 
>> >> voltage measured is reduced to zero. The current you have to inject will 
>> >> be the same magnitude but opposite direction to the unknown load current.
>> >> 
>> >> piglet
>> >
>> >You don't need to cancel the trace current--just injecting a calibrated
>> >a.c. current between the two probes would be good enough to measure the
>> >trace resistance, then compute the d.c. current from the d.c. drop.
>> >
>> 
>> Just power the board down and measure the trace resistance!
>
>Sure, but we're talking an automated instrument do that all in one go,
>without having to make a separate 4-wire resistance measurement.
> 
>> Another trick is to measure the drop in a trace, add a dummy load
>> resistor, note the delta-v, and do the math.
>>
>> Or measure the trace resistance on a bare board from the same batch.
>
>I like the magnetic probe for qualitative info.  Maybe a Hall probe
>could do it too.
>
>We need a FLIR for magnetic flux.

It would be cool to see the mag fields around a board.


-- 

John Larkin         Highland Technology, Inc

lunatic fringe electronics 

[toc] | [prev] | [next] | [standalone]

#450649

On Mon, 06 Mar 2017 21:36:47 -0800, John Larkin wrote:

> It would be cool to see the mag fields around a board.

That's easy. Just sprinkle it with iron fillings. ;->

[toc] | [prev] | [next] | [standalone]

#450697

On Tuesday, March 7, 2017 at 10:14:18 AM UTC-8, Cursitor Doom wrote:
> On Mon, 06 Mar 2017 21:36:47 -0800, John Larkin wrote:
> 
> > It would be cool to see the mag fields around a board.
> 
> That's easy. Just sprinkle it with iron fillings. ;->

Or the modern equivalent

<http://www.arborsci.com/magnetic-field-viewer-film-9in-x-7-2in>

[toc] | [prev] | [next] | [standalone]

#450731

On Tue, 07 Mar 2017 14:03:19 -0800, whit3rd wrote:

> Or the modern equivalent
> 
> <http://www.arborsci.com/magnetic-field-viewer-film-9in-x-7-2in>

That promo shot looks terrible.

[toc] | [prev] | [next] | [standalone]

#451194

On 03/07/2017 02:03 PM, whit3rd wrote:
> On Tuesday, March 7, 2017 at 10:14:18 AM UTC-8, Cursitor Doom wrote:
>> On Mon, 06 Mar 2017 21:36:47 -0800, John Larkin wrote:
>>
>>> It would be cool to see the mag fields around a board.
>>
>> That's easy. Just sprinkle it with iron fillings. ;->
>
> Or the modern equivalent
>
> <http://www.arborsci.com/magnetic-field-viewer-film-9in-x-7-2in>
>
Huh? "Bulk magnetic field viewing film, 9in. x 7.2in. Can be cut up into 
student sizes for the whole class to explore magnetic fields. Or use it 
in a complete sheet to see an entire magnet's field lines."

Those must be small students... :-)

[toc] | [prev] | [next] | [standalone]

#450625

On Tuesday, March 7, 2017 at 1:17:36 AM UTC-4, dagmarg...@yahoo.com wrote:
>  
> > Another trick is to measure the drop in a trace, add a dummy load
> > resistor, note the delta-v, and do the math.
> >
> > Or measure the trace resistance on a bare board from the same batch.
> 
> I like the magnetic probe for qualitative info.  Maybe a Hall probe
> could do it too.
> 
> We need a FLIR for magnetic flux.
> 
> Cheers,
> James Arthur

Hello James,

That would called an EMSCAN.
https://www.emscan.com/

 - Wolfgang.

[toc] | [prev] | [next] | [standalone]

#450627

On Tuesday, March 7, 2017 at 10:35:15 AM UTC-5, wolfgangf...@gmail.com wrote:
> On Tuesday, March 7, 2017 at 1:17:36 AM UTC-4, dagmarg...@yahoo.com wrote:
> >  
> > > Another trick is to measure the drop in a trace, add a dummy load
> > > resistor, note the delta-v, and do the math.
> > >
> > > Or measure the trace resistance on a bare board from the same batch.
> > 
> > I like the magnetic probe for qualitative info.  Maybe a Hall probe
> > could do it too.
> > 
> > We need a FLIR for magnetic flux.
> > 
> > Cheers,
> > James Arthur
> 
> Hello James,
> 
> That would called an EMSCAN.
> https://www.emscan.com/
> 
>  - Wolfgang.

AWESOME.

Cheers,
James Arthur

[toc] | [prev] | [next] | [standalone]

#450744

On Tue, 7 Mar 2017 07:35:06 -0800 (PST), wolfgangfriedrich42@gmail.com
wrote:

>On Tuesday, March 7, 2017 at 1:17:36 AM UTC-4, dagmarg...@yahoo.com wrote:
>>  
>> > Another trick is to measure the drop in a trace, add a dummy load
>> > resistor, note the delta-v, and do the math.
>> >
>> > Or measure the trace resistance on a bare board from the same batch.
>> 
>> I like the magnetic probe for qualitative info.  Maybe a Hall probe
>> could do it too.
>> 
>> We need a FLIR for magnetic flux.
>> 
>> Cheers,
>> James Arthur
>
>Hello James,
>
>That would called an EMSCAN.
>https://www.emscan.com/

We have one of those.  Great tool when we can't get chamber time.  ;-)

[toc] | [prev] | [next] | [standalone]

#450784

On 03/07/2017 08:56 PM, krw@notreal.com wrote:
> On Tue, 7 Mar 2017 07:35:06 -0800 (PST), wolfgangfriedrich42@gmail.com
> wrote:
> 
>> On Tuesday, March 7, 2017 at 1:17:36 AM UTC-4, dagmarg...@yahoo.com wrote:
>>>  
>>>> Another trick is to measure the drop in a trace, add a dummy load
>>>> resistor, note the delta-v, and do the math.
>>>>
>>>> Or measure the trace resistance on a bare board from the same batch.
>>>
>>> I like the magnetic probe for qualitative info.  Maybe a Hall probe
>>> could do it too.
>>>
>>> We need a FLIR for magnetic flux.
>>>
>>> Cheers,
>>> James Arthur
>>
>> Hello James,
>>
>> That would called an EMSCAN.
>> https://www.emscan.com/
> 
> We have one of those.  Great tool when we can't get chamber time.  ;-)
> 

What did it set you back?

Cheers

Phil Hobbs


-- 
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

[toc] | [prev] | [next] | [standalone]

#450793

Phil Hobbs wrote...
>
> krw@notreal.com wrote:
>> wolfgangfriedrich42@gmail.com wrote:
>>> dagmarg...@yahoo.com wrote:
>>>>  
>>>> We need a FLIR for magnetic flux.
>>>>
>>>> Cheers,
>>>> James Arthur
>>>
>>> Hello James,
>>>
>>> That would called an EMSCAN.
>>> https://www.emscan.com/
>> 
>> We have one of those.  Great tool when we can't get chamber time.  ;-)
>
> What did it set you back?

 Yes, looks really expensive.


-- 
 Thanks,
    - Win

[toc] | [prev] | [next] | [standalone]

#450815

On Wednesday, March 8, 2017 at 11:21:58 AM UTC-4, Winfield Hill wrote:
> Phil Hobbs wrote...
> >
> > krw wrote:
> >> wolfgangfriedrich wrote:
> >>> dagmarg wrote:
> >>>>  
> >>>> We need a FLIR for magnetic flux.
> >>>>
> >>>> Cheers,
> >>>> James Arthur
> >>>
> >>> Hello James,
> >>>
> >>> That would called an EMSCAN.
> >>> https://www.emscan.com/
> >> 
> >> We have one of those.  Great tool when we can't get chamber time.  ;-)
> >
> > What did it set you back?
> 
>  Yes, looks really expensive.
> 
> 
> -- 
>  Thanks,
>     - Win

Not sure, I would guess somewhere in the lower 5 figures range.
That's what it was ~10 years back when the support box was the size of a desktop PC and you would need a specific spectrum analyser with GPIB interface along side. My old office was a short drive from their location, so we never bought one but used them as consultants. :)
Once the device showed us a standing wave of a higher harmonic of a clock on a FFC. A really great debugging tool. 
Cheers,
 - Wolfgang.

[toc] | [prev] | [next] | [standalone]

#450914

On Wed, 8 Mar 2017 09:00:18 -0800 (PST), wolfgangfriedrich42@gmail.com
wrote:

>On Wednesday, March 8, 2017 at 11:21:58 AM UTC-4, Winfield Hill wrote:
>> Phil Hobbs wrote...
>> >
>> > krw wrote:
>> >> wolfgangfriedrich wrote:
>> >>> dagmarg wrote:
>> >>>>  
>> >>>> We need a FLIR for magnetic flux.
>> >>>>
>> >>>> Cheers,
>> >>>> James Arthur
>> >>>
>> >>> Hello James,
>> >>>
>> >>> That would called an EMSCAN.
>> >>> https://www.emscan.com/
>> >> 
>> >> We have one of those.  Great tool when we can't get chamber time.  ;-)
>> >
>> > What did it set you back?
>> 
>>  Yes, looks really expensive.
>> 
>> 
>> -- 
>>  Thanks,
>>     - Win
>
>Not sure, I would guess somewhere in the lower 5 figures range.
>That's what it was ~10 years back when the support box was the size of a desktop PC and you would need a specific spectrum analyser with GPIB interface along side. My old office was a short drive from their location, so we never bought one but used them as consultants. :)
>Once the device showed us a standing wave of a higher harmonic of a clock on a FFC. A really great debugging tool. 
>Cheers,
> - Wolfgang.

I think that's about right ($20K-$30K).  A mere bag of shells compared
to a lot of other EMI tools (ever price out a 3M chamber? ;-).  Well
worth the money.

[toc] | [prev] | [next] | [standalone]

#451086

On Wednesday, March 8, 2017 at 7:21:58 AM UTC-8, Winfield Hill wrote:
> Phil Hobbs wrote...
> >
> > krw@notreal.com wrote:
> >> wolfgangfriedrich42@gmail.com wrote:
> >>> dagmarg...@yahoo.com wrote:

> >>>> We need a FLIR for magnetic flux.

> >>> That would called an EMSCAN.
> >>> https://www.emscan.com/
 
> >> We have one of those.  Great tool when we can't get chamber time.  ;-)

> > What did it set you back?
 
>  Yes, looks really expensive.

Can you still get disclosing fluid?   It was a paramagnetic liquid, usually
in a spraybottle, that indicates field.   Used on mag tape (or floppies)
it tells you whether your eight-track tape recorder is firing on all eight tracks.

Kyread is the brand I've used.   It evaporates and leaves no residue.

I think it's a fluid-in -fluid suspension, and droplets elongate in response to
field strength and direction.

[toc] | [prev] | [next] | [standalone]

#450912

On Wed, 8 Mar 2017 09:36:21 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>On 03/07/2017 08:56 PM, krw@notreal.com wrote:
>> On Tue, 7 Mar 2017 07:35:06 -0800 (PST), wolfgangfriedrich42@gmail.com
>> wrote:
>> 
>>> On Tuesday, March 7, 2017 at 1:17:36 AM UTC-4, dagmarg...@yahoo.com wrote:
>>>>  
>>>>> Another trick is to measure the drop in a trace, add a dummy load
>>>>> resistor, note the delta-v, and do the math.
>>>>>
>>>>> Or measure the trace resistance on a bare board from the same batch.
>>>>
>>>> I like the magnetic probe for qualitative info.  Maybe a Hall probe
>>>> could do it too.
>>>>
>>>> We need a FLIR for magnetic flux.
>>>>
>>>> Cheers,
>>>> James Arthur
>>>
>>> Hello James,
>>>
>>> That would called an EMSCAN.
>>> https://www.emscan.com/
>> 
>> We have one of those.  Great tool when we can't get chamber time.  ;-)
>> 
>
>What did it set you back?

Dunno.  I think it was bought before I was hired (5 years).

[toc] | [prev] | [next] | [standalone]

#450612

On Monday, March 6, 2017 at 9:26:46 PM UTC-5, dagmarg...@yahoo.com wrote:
> On Monday, March 6, 2017 at 9:08:58 AM UTC-5, piglet wrote:
> > On 06/03/2017 13:47, George Herold wrote:
> > > On Monday, March 6, 2017 at 5:28:11 AM UTC-5, piglet wrote:
> > >> If it's a kelvin connection to the pcb trace then you could neatly
> > >> disregard the trace resistance by injecting a servo current to bring the
> > >> IR drop to zero.
> > >
> > > Huh, push current back through the voltage leads of the Kelvin connection.
> > > I drew that but now I've got all the current flowing through the voltage
> > > leads... seems like I need yet another pair of leads.. A six wire "Kelvin"
> > > connection.  Or I didn't draw it right.
> > >
> > > George H.
> > >
> > >>
> > >> piglet
> > >
> > 
> > So imagine a pcb trace carrying the unknown load current. Place four 
> > test probes in a line along that trace. Measure the voltage between the 
> > inner pair and inject a current through the outer pair such that the 
> > voltage measured is reduced to zero. The current you have to inject will 
> > be the same magnitude but opposite direction to the unknown load current.
> > 
> > piglet
> 
> You don't need to cancel the trace current--just injecting a calibrated
> a.c. current between the two probes would be good enough to measure the
> trace resistance, then compute the d.c. current from the d.c. drop.

OK next you'll be synchronously detecting the AC. :^)
George H.   

> 
> Cheers,
> James Arthur

[toc] | [prev] | [next] | [standalone]

#450616

On Tuesday, March 7, 2017 at 8:43:01 AM UTC-5, George Herold wrote:
> On Monday, March 6, 2017 at 9:26:46 PM UTC-5, dagmarg...@yahoo.com wrote:
> > On Monday, March 6, 2017 at 9:08:58 AM UTC-5, piglet wrote:
> > > On 06/03/2017 13:47, George Herold wrote:
> > > > On Monday, March 6, 2017 at 5:28:11 AM UTC-5, piglet wrote:
> > > >> If it's a kelvin connection to the pcb trace then you could neatly
> > > >> disregard the trace resistance by injecting a servo current to bring the
> > > >> IR drop to zero.
> > > >
> > > > Huh, push current back through the voltage leads of the Kelvin connection.
> > > > I drew that but now I've got all the current flowing through the voltage
> > > > leads... seems like I need yet another pair of leads.. A six wire "Kelvin"
> > > > connection.  Or I didn't draw it right.
> > > >
> > > > George H.
> > > >
> > > >>
> > > >> piglet
> > > >
> > > 
> > > So imagine a pcb trace carrying the unknown load current. Place four 
> > > test probes in a line along that trace. Measure the voltage between the 
> > > inner pair and inject a current through the outer pair such that the 
> > > voltage measured is reduced to zero. The current you have to inject will 
> > > be the same magnitude but opposite direction to the unknown load current.
> > > 
> > > piglet
> > 
> > You don't need to cancel the trace current--just injecting a calibrated
> > a.c. current between the two probes would be good enough to measure the
> > trace resistance, then compute the d.c. current from the d.c. drop.
> 
> OK next you'll be synchronously detecting the AC. :^)
> George H.   

Of course, that's the reason for using a.c.!

Cheers,
James Arthur

[toc] | [prev] | [next] | [standalone]

Page 3 of 4 — ← Prev page 1 2 [3] 4  Next page →

Back to top | Article view | sci.electronics.design

csiph-web