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 1 of 4  [1] 2 3 4  Next page →

#450285 — A useful addition to your toolkit

https://www.sparkfun.com/products/11005

Replace the existing connector with a BNC, add a bit of series resistance 
and you have a *very* cheap current probe for your scope.

[toc] | [next] | [standalone]

#450292

On Sun, 5 Mar 2017 14:48:51 -0000 (UTC), Cursitor Doom
<curd@notformail.com> wrote:

>https://www.sparkfun.com/products/11005
>
>Replace the existing connector with a BNC, add a bit of series resistance 
>and you have a *very* cheap current probe for your scope.

I have a clamp-on ammeter that pretty much does that, although it just
indicates amps, and doesn't allow waveform snooping. 60 Hz waveforms
aren't terribly interesting.

My real problem with current measurement is DC, on PC boards. We want
to know how much current, say, an FPGA is using. Sometimes I include
current shunts in a layout, but sometimes I don't.

One can use existing switcher inductors as current shunts. I wish I
had a PCB trace current probe, but that's probably not posssible. You
can measure millivolt and microvolt drops across traces and vias.




-- 

John Larkin         Highland Technology, Inc

lunatic fringe electronics 

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

#450298

On Sun, 05 Mar 2017 07:44:18 -0800, John Larkin wrote:

> I have a clamp-on ammeter that pretty much does that, although it just
> indicates amps, and doesn't allow waveform snooping. 60 Hz waveforms
> aren't terribly interesting.

Indeed they're not. But your meter is presumably *only* designed for use 
at 60Hz, I would imagine. Hook it up to a 100Hz signal and you'll see 
nothing at all in all probability. ;-)

> One can use existing switcher inductors as current shunts. I wish I had
> a PCB trace current probe, but that's probably not posssible. You can
> measure millivolt and microvolt drops across traces and vias.

Do they even exist? That would be amazing but no doubt *way* beyond what 
I can justify to splash out on as a mere hobbyist.

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

#450309

On Sun, 5 Mar 2017 16:18:50 -0000 (UTC), Cursitor Doom
<curd@notformail.com> wrote:

>On Sun, 05 Mar 2017 07:44:18 -0800, John Larkin wrote:
>
>> I have a clamp-on ammeter that pretty much does that, although it just
>> indicates amps, and doesn't allow waveform snooping. 60 Hz waveforms
>> aren't terribly interesting.
>
>Indeed they're not. But your meter is presumably *only* designed for use 
>at 60Hz, I would imagine. Hook it up to a 100Hz signal and you'll see 
>nothing at all in all probability. ;-)
>
>> One can use existing switcher inductors as current shunts. I wish I had
>> a PCB trace current probe, but that's probably not posssible. You can
>> measure millivolt and microvolt drops across traces and vias.
>
>Do they even exist? That would be amazing but no doubt *way* beyond what 
>I can justify to splash out on as a mere hobbyist.


A 1" long, 20 mil wide 1oz trace will be about 25 milliohms. 1 amp
makes 25 millivolts, and lots of cheapish DVMs will resolve that well
enough. You probably need a bench DVM with microvolt resolution to
measure, say, 1 amp running through a via, but you could build a
little microvolt meter or amp pretty easily. PCB trace and via
resistances need to be calibrated, which is only a minor nuisance.

Here are some pcb-trace shunts, down near the connector:

https://dl.dropboxusercontent.com/u/53724080/PCBs/TEM2_Power_Board.JPG

One of the great mysteries of electronics is "where is the current
going?" Sometimes a thermal imager helps figure that out. A little
magnetometer would be fun, not hard to do these days.




-- 

John Larkin         Highland Technology, Inc

lunatic fringe electronics 

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

#450342

In article <fuhobcdhvlfcm9ik7kk4kr9fkddfpa1jon@4ax.com>, 
jjlarkin@highlandtechnology.com says...
> 
> One of the great mysteries of electronics is "where is the current
> going?" Sometimes a thermal imager helps figure that out. A little
> magnetometer would be fun, not hard to do these days.

Reading the blurb on the cited current transformer reminded me of a 
puzzle for all clamp meters... Surely they are no good clamped on a 
normal bi-directional power cable in which the current is both coming 
and going: the magnetic fields will near-perfectly cancel out. Surely 
you have to split the cable to measure current?

Mike.

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

#450344

They do make special current probes specifically for doing traces
on a PC board. without cutting traces or requiring a loop of wire.
<http://www.power-mag.com/pdf/feature_pdf/1327592496_TTI_Layout_1.pdf>


-- 
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com

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

#450348

On Sun, 5 Mar 2017 15:07:41 -0600, Foxs Mercantile <jdangus@att.net>
wrote:

>They do make special current probes specifically for doing traces
>on a PC board. without cutting traces or requiring a loop of wire.
><http://www.power-mag.com/pdf/feature_pdf/1327592496_TTI_Layout_1.pdf>

Looks expensive, and I'd guess not very accurate.


-- 

John Larkin         Highland Technology, Inc

lunatic fringe electronics 

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

#450356

On 3/5/2017 3:37 PM, John Larkin wrote:
> Looks expensive, and I'd guess not very accurate.

<http://www.aimtti.us/product-category/current-probes/aim-i-prober-520>
It is expensive. At $795 for the basic probe.
Data sheet:
<http://resources.aimtti.com/datasheets/prec-iprober520-5p.pdf>
Instruction manual:
<http://resources.aimtti.com/manuals/I-prober_Instruction_Manual-Iss5.pdf>



-- 
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com

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

#450367

Foxs Mercantile wrote...
>
> John Larkin wrote:
>> Looks expensive, and I'd guess not very accurate.
>
><http://www.aimtti.us/product-category/current-probes/aim-i-prober-520>
>It is expensive. At $795 for the basic probe.
>Data sheet:
><http://resources.aimtti.com/datasheets/prec-iprober520-5p.pdf>
>Instruction manual:
><http://resources.aimtti.com/manuals/I-prober_Instruction_Manual-Iss5.pdf>

 The expense we can handle, if, for example, it'll
 give us adequate help in debugging our switching
 power supply designs.  But the calibrating scheme
 for trace current measurements looks iffy.  But
 maybe along with other measurements, power in,
 voltage and power out, etc., it could do the job.
 It is fast enough to look at inductor currents.


-- 
 Thanks,
    - Win

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

#450416

On 3/5/2017 4:37 PM, John Larkin wrote:
> On Sun, 5 Mar 2017 15:07:41 -0600, Foxs Mercantile <jdangus@att.net>
> wrote:
>
>> They do make special current probes specifically for doing traces
>> on a PC board. without cutting traces or requiring a loop of wire.
>> <http://www.power-mag.com/pdf/feature_pdf/1327592496_TTI_Layout_1.pdf>
>
> Looks expensive, and I'd guess not very accurate.

Seems to me it would be a *great* tool for finding where the currents 
are going.  I thought that would be a good thing?

-- 

Rick C

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

#450417

On 3/5/2017 11:58 PM, rickman wrote:
>
> Seems to me it would be a *great* tool for finding where the
> currents are going.  I thought that would be a good thing?

It is. But some people have difficulty accepting anything more
complicated than a light bulb, or more expensive than a pack of
cigarettes.


-- 
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com

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

#450419

On 3/6/2017 1:56 AM, Foxs Mercantile wrote:
> On 3/5/2017 11:58 PM, rickman wrote:
>>
>> Seems to me it would be a *great* tool for finding where the
>> currents are going.  I thought that would be a good thing?
>
> It is. But some people have difficulty accepting anything more
> complicated than a light bulb, or more expensive than a pack of
> cigarettes.

You mean like thermal cameras?

-- 

Rick C

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

#450431

On Mon, 06 Mar 2017 00:56:56 -0600, Foxs Mercantile wrote:

> It is. But some people have difficulty accepting anything more
> complicated than a light bulb, or more expensive than a pack of
> cigarettes.

For the *real* cheapskates out there, there's this alternative:

http://www.ebay.com/itm/100A-SCT-013-000-Non-invasive-AC-current-sensor-
Split-Core-Transformer-YH-/201842524936?
hash=item2efec08308:g:vm8AAOSwCGVX3BYF

Claims to be able to handle up to 100A!

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

#450552

Cursitor Doom wrote:
> On Mon, 06 Mar 2017 00:56:56 -0600, Foxs Mercantile wrote:
>
>> It is. But some people have difficulty accepting anything more
>> complicated than a light bulb, or more expensive than a pack of
>> cigarettes.
>
> For the *real* cheapskates out there, there's this alternative:
>
> http://www.ebay.com/itm/201842524936
>
> Claims to be able to handle up to 100A!


    Let's see you use it to find a stray 100 mA DC on a crowded circuit 
board.  :(


-- 
Never piss off an Engineer!

They don't get mad.

They don't get even.

They go for over unity! ;-)

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

#450650

On Mon, 06 Mar 2017 20:56:02 -0500, Michael A. Terrell wrote:

>     Let's see you use it to find a stray 100 mA DC on a crowded circuit
> board.  :(

Oh come along now. You know it's not intended for that sort of usage!

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

#450780

Cursitor Doom wrote...
>
> Michael A. Terrell wrote:
>
>> Let's see you use it to find a stray 100 mA DC
>> on a crowded circuit board.  :(
>
> Oh come along now. You know it's not intended for
> that sort of usage!

 I ordered one from Newark, and plan to use it
 on my messed-up switching power-supply designs.
 Qualitative results will be fine.


-- 
 Thanks,
    - Win

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

#450787

On Wed, 08 Mar 2017 05:44:39 -0800, Winfield Hill wrote:

>  I ordered one from Newark, and plan to use it on my messed-up switching
>  power-supply designs.
>  Qualitative results will be fine.

Mine arrived today. I plan to monitor fuel injection impulses with it 
firstly just to see what kind of di/dt responses it's capable of. I'm not 
quite as confident as you are, though!

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

#450792

Cursitor Doom wrote...
>
> On Wed, 08 Mar 2017 05:44:39 -0800, Winfield Hill wrote:
>
>>  I ordered one from Newark, and plan to use it on my messed-up switching
>>  power-supply designs.
>>  Qualitative results will be fine.
>
> Mine arrived today. I plan to monitor fuel injection
> impulses with it firstly just to see what kind of
> di/dt responses it's capable of. I'm not quite as
> confident as you are, though!

 I do a lot of fast HV pulsing circuitry, and don't
 expect it'll be helpful for that kind of work.  But
 the 5MHz bandwidth should be fine for looking at
 inductor current ramps, cap charge-discharge, etc.


-- 
 Thanks,
    - Win

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

#450898

On 2017-03-08, Winfield Hill <hill@rowland.harvard.edu> wrote:
> Cursitor Doom wrote...
>>
>> Michael A. Terrell wrote:
>>
>>> Let's see you use it to find a stray 100 mA DC
>>> on a crowded circuit board.  :(
>>
>> Oh come along now. You know it's not intended for
>> that sort of usage!
>
>  I ordered one from Newark, and plan to use it
>  on my messed-up switching power-supply designs.
>  Qualitative results will be fine.

a few years back there was talk of using a video head from a VCR
(after removing it from the drum) to probe AC currents. It should be good
to a few megahertz. a core from an ethernet transformer with a gap
added could be another option. a spool-shaped inductor would
probably work too.


-- 
This email has not been checked by half-arsed antivirus software 

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

#450900

On 8 Mar 2017 18:53:52 GMT, Jasen Betts <jasen@xnet.co.nz> wrote:

>On 2017-03-08, Winfield Hill <hill@rowland.harvard.edu> wrote:
>> Cursitor Doom wrote...
>>>
>>> Michael A. Terrell wrote:
>>>
>>>> Let's see you use it to find a stray 100 mA DC
>>>> on a crowded circuit board.  :(
>>>
>>> Oh come along now. You know it's not intended for
>>> that sort of usage!
>>
>>  I ordered one from Newark, and plan to use it
>>  on my messed-up switching power-supply designs.
>>  Qualitative results will be fine.
>
>a few years back there was talk of using a video head from a VCR
>(after removing it from the drum) to probe AC currents. It should be good
>to a few megahertz. a core from an ethernet transformer with a gap
>added could be another option. a spool-shaped inductor would
>probably work too.

A little unshielded drum-core inductor is a handy h-field probe.


-- 

John Larkin         Highland Technology, Inc
picosecond timing   precision measurement 

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

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

Page 1 of 4  [1] 2 3 4  Next page →

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

csiph-web