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John Larkin <jjlarkin@highlandtechnology.com>: Mar 05 09:28AM -0800 On Sun, 5 Mar 2017 16:18:50 -0000 (UTC), Cursitor Doom >> 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

MJC <gravity@mjcoon.plus.com>: Mar 05 08:56PM 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.

Foxs Mercantile <jdangus@att.net>: Mar 05 03:07PM -0600 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

John Larkin <jjlarkin@highlandtechnology.com>: Mar 05 01:37PM -0800 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

Foxs Mercantile <jdangus@att.net>: Mar 05 05:41PM -0600 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

Winfield Hill <hill@rowland.harvard.edu>: Mar 05 04:35PM -0800 Foxs Mercantile wrote... ><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

krw@notreal.com: Mar 05 07:41PM -0500 On Sun, 05 Mar 2017 07:44:18 -0800, John Larkin   >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.   I generally use a ferrite (pi filter) on the supplies to uCs and DSPs for EMI, then substitute a shunt to measure the power during test.   >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.   The old HP current probe was a great debugging tool.

Phil Allison <pallison49@gmail.com>: Mar 05 05:15PM -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.   ** Mains current waveforms are VERY interesting, but not if all you can see is 60Hz. A Hall effect transducer is needed to do the job properly.   The one is use is by LEM and has response to 100kHz, allows me to see currents as low as 1mA and up to 100A peak.     .... Phil

JM <dontreplytothis173@gmail.com>: Mar 05 07:56PM On 05/03/2017 15:44, 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.   Tell that to a condition monitoring engineer!

John Larkin <jjlarkin@highlandtechnology.com>: Mar 05 08:02PM -0800 On Sun, 05 Mar 2017 19:56:44 +0000, JM <dontreplytothis173@gmail.com> wrote:   >> indicates amps, and doesn't allow waveform snooping. 60 Hz waveforms >> aren't terribly interesting.   >Tell that to a condition monitoring engineer!   I don't design AC power supplies any more. I can buy an entire nice PFC switcher for less than I could buy a 60 Hz power transformer. Since the supplies all come with UL/CE/VDE/etc stickers, I don't care about their input current waveforms.     --   John Larkin Highland Technology, Inc   lunatic fringe electronics

rickman <gnuarm@gmail.com>: Mar 06 12:58AM -0500 On 3/5/2017 4:37 PM, John Larkin wrote: >> 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

Foxs Mercantile <jdangus@att.net>: Mar 06 12:56AM -0600 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

jurb6006@gmail.com: Mar 05 07:59PM -0800 >"** Fraid that ref does not mention the spec.   You bullshitting fucking idiot. "   Bullshit, it says 500 fucking volts. Now who cannot read ?   Let's go ahead and fuck up Usenet with a flame war ey ?   And you will lose.

"Michael A. Terrell" <mike.terrell@earthlink.net>: Mar 05 12:17PM -0500 > file:///C:/Users/Peter/Downloads/corrosion_of_silver_plated_copper_conductor.pdf     Come on, Peter. Another link to your C: drive?     -- Never piss off an Engineer!   They don't get mad.   They don't get even.   They go for over unity! ;-)

"pfjw@aol.com" <pfjw@aol.com>: Mar 05 12:15PM -0800 https://escies.org/download/webDocumentFile?id=62170   See if this works - or use the title:   Corrosion of Silver Plate Copper Conductor   If one hits the link, it automatically downloads the .pdf, making a C: Drive link - which I did not notice.   Peter Wieck Melrose Park, PA

"Benderthe.evilrobot" <Benderthe.evilrobot@virginmedia.com>: Mar 05 09:53PM "John Robertson" <spam@flippers.com> wrote in message news:LbadnR13oZ3vLibFnZ2dnUU7-RGdnZ2d@giganews.com...   >> ** It's got be due to silver plating the leads.   > I'm sure they thought that silver plating was a good idea, instead of > planned obsolescence.   My first job was fault finding huge desk calculators that only did the most basic functions and contained about 200 DTL chips.   Most of the chips had silver plated pins and I never had a fault because of that - a few chips had gold plated pins, there may have been less than half-dozen faults because the alloy interface became an insulator (there was no inherently dodgy RoHS soldering back then).   You could always tell the silver plated ones because the pins were black. The tinned ones never got past dull grey.

"Benderthe.evilrobot" <Benderthe.evilrobot@virginmedia.com>: Mar 05 09:55PM "Michael A. Terrell" <mike.terrell@earthlink.net> wrote in message news:3_OdnerXncqr1SHFnZ2dnUU7-W2dnZ2d@earthlink.com... > pfjw@aol.com wrote: >> file:///C:/Users/Peter/Downloads/corrosion_of_silver_plated_copper_conductor.pdf   > Come on, Peter. Another link to your C: drive?   Couldn't open that - maybe someone formatted it.......................

Phil Allison <pallison49@gmail.com>: Mar 05 05:27PM -0800 > https://escies.org/download/webDocumentFile?id=62170   > See if this works - or use the title:   > Corrosion of Silver Plate Copper Conductor   ** The link is about another topic entirely.   It neither supports or contradicts what has been said here.   The Wieck troll had no basis for his mad asssetions.   It's just his OWN theory.   Fuck off you bullshitting idiot.     .... Phil

"pfjw@aol.com" <pfjw@aol.com>: Mar 05 05:50PM -0800 What you missed twit, is that the silver is not contributory to the corrosion. That copper is sacrificial to silver, and that the cause is air/water getting to the copper due to cracks/failure in the plating.   Again, this process is well understood and often exploited by jewelers and metalsmiths. It's a big world out there, jackass - try learning something.   Peter Wieck Melrose Park, PA

Phil Allison <pallison49@gmail.com>: Mar 05 07:31PM -0800 > What you missed twit,       ** Fraid you missed the entire point. Cos you are an absolute, fucking nut case.   Piss OFF you damn TROLL.       ..... Phil

vjp2.at@at.BioStrategist.dot.dot.com: Mar 05 08:01PM Got a notice about retirement of copper   Most important will dialup modems and fax work?   A while back almost had to because squirrel ate my line   My line comes in from back of house but power from front. But my phone lines branch out form middle of basement where laundry & hVAC are and there is plenty power. Grammar school chum who became electrician told me I should tell them to install fiber there. (He said some may be ornery but I would be right torequest it.)   Now new notice says I can have OPTIONAL backup power and they use D batts. Maybe they have changed?   Other than tell them to put it midhouse, do I have anything else to worry about?   - = - Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist http://www.panix.com/~vjp2/vasos.htm ---{Nothing herein constitutes advice. Everything fully disclaimed.}--- [Homeland Security means private firearms not lazy obstructive guards] [Urb sprawl confounds terror] [Phooey on GUI: Windows for subprime Bimbos]

"pfjw@aol.com" <pfjw@aol.com>: Mar 05 01:04PM -0800 When copper goes away, so will "robust" phone systems, big central switches, and line-powered devices such as ringers and flashers (for deaf people).   What good does as battery back-up do when power goes down and your local fiber-box (NOT backed up by batteries) goes down with it.   When Sandy struck around here, our (copper-based) phones worked just fine. Fios, Comcast and the rest of them did not until the providers put a small portable generator chained to each pole with a box. That took about 48 hours. Some cell towers were down after their batteries local failed - again until the providers brought in generators. But those were a bit larger. Power was out for a full seven (7) days.   Although we have a generator, our phones never failed during that time, even for a moment.   And for those who are really paranoid - a conventional dial-type ringer phone on a copper network fed from a central switch remains pretty much immune to EMPs. Lot of good that will do, except for, perhaps, the roaches.   Peter Wieck

vjp2.at@at.BioStrategist.dot.dot.com: Mar 06 12:38AM Yeah, I know. The squirrel cut my line a few weeks after Sandy.   Cable and fiber were down all over my nabe during Sandy     Which brings me to ask:     Will DSL and surge filters interfere? I don't nee dthem to work. Obviously, fibe ris immune to lighnting (is it?) and the DSL never worked, but i don't rememeber wher eall the filters are.   I rememmber during the 1977 blackout I found out my line was 48volts. How do they do 48v with D batts?   - = - Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist http://www.panix.com/~vjp2/vasos.htm ---{Nothing herein constitutes advice. Everything fully disclaimed.}--- [Homeland Security means private firearms not lazy obstructive guards] [Urb sprawl confounds terror] [Phooey on GUI: Windows for subprime Bimbos]

Foxs Mercantile <jdangus@att.net>: Mar 05 07:22PM -0600 > I rememmber during the 1977 blackout I found out my line was 48volts. > How do they do 48v with D batts?   They don't use D batteries. <https://assets.wired.com/photos/w_3360/wp-content/uploads/2016/09/Payne003.jpg>     -- Jeff-1.0 wa6fwi http://www.foxsmercantile.com

"Michael A. Terrell" <mike.terrell@earthlink.net>: Mar 05 12:14PM -0500 > Well then go back to your Usenet posts from ten fucking years ago and change those URLs.   > You cool with that ?     Show me some that need changed, that weren't for business websites.     -- Never piss off an Engineer!   They don't get mad.   They don't get even.   They go for over unity! ;-)

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