The Cyber-Spy.Com Usenet Archive Feeds Directly
From The Open And Publicly Available Newsgroup
This Group And Thousands Of Others Are Available
On Most IS NNTP News Servers On Port 119.
Cyber-Spy.Com Is NOT Responsible For Any Topic,
Opinions Or Content Posted To This Or Any Other
Newsgroup. This Web Archive Of The Newsgroup And
Posts Are For Informational Purposes Only.
From: "Michael A. Terrell"
Subject: Re: Short Circuit Detector
Date: Fri, 11 Oct 2002 20:40:20 -0400
Organization: Do I have to? Well, Ok. If you insist!
X-Mailer: Mozilla 4.61 [en]C-CCK-MCD (Win95; U)
References: <firstname.lastname@example.org> <email@example.com>
Jim Thompson wrote:
> On Fri, 11 Oct 2002 18:17:07 +0200,
> "fred bartoli" ,
> In Newsgroup: sci.electronics.design,
> Article: <firstname.lastname@example.org>,
> Entitled: "Re: Short Circuit Detector",
> Wrote the following:
> |For copper planes, sheet resistance is about 0.5mohm/square for 35um and
> |1mohm/square for 17um thickness.
> |So you'd better have a sensitive meter, (maybe add a gain stage).
> |Then set to say 100/500mA the current, and protect your circuit with a
> |schottky between vcc-gnd : it's easy to have the psu voltage button
> |accidentally turned in case it happens the short opens... by himself. (I had
> |that and once corrected for the short I just had to drop the fried board :-(
> |> Steve
> |> "Nico Coesel" wrote in message
> |> news:email@example.com...
> |> > "red rover" wrote:
> |> >
> |> > >Does anyone have link to a design for
> |> > >short circuit detector? I recall that Bob
> |> > >Pease had a design for one in his Analog
> |> > >Troubleshooting book. I believe it was
> |> > >basically a micro ohmeter with an audio
> |> > >output and you worked your way around
> |> > >the pcb homing in on the fault.
> |> > >
> |> > >Anybody here made one? Any good success?
> |> >
> |> > I've found that most short circuits on a PCB are in power
> |> > distribution. In case of such a short circuit I simply connect a PSU
> |> > set at a -safe- low voltage (current limit set to 1A; depending on
> |> > minimum trace width) to the board. By measuring the voltage accross
> |> > the decoupling capacitors (to start with) I can determine the area
> |> > where the short should be. The closer you get to the short circuit,
> |> > the less voltage you measure.
> |> >
> |> > --
> |> > Reply to nico@nctdevpuntnl (punt=.)
> I once cured some shorted thick-film substrates by applying a 5V/200A
> supply ;-)
> ...Jim Thompson
> | James E.Thompson, P.E. | mens |
> | Analog Innovations, Inc. | et |
> | Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
> | Phoenix, Arizona Voice:(480)460-2350 | |
> | Jim-T@analog_innovations.com Fax:(480)460-2142 | Brass Rat |
> | http://www.analog-innovations.com | 1962 |
> For proper E-mail replies SWAP "-" and "_"
> I love to cook with wine. Sometimes I even put it in the food.
I had a guy bet me I couldn't find the short and fix a shorted piece
of RG/8 coax with a PL-259 at each end. I popped the hood on my car,
center pin to one terminal, shell to the other. It started to smoke and
burn near one connector so I cut it off at the burn and put the
connector back on.
My motto: "Always use the right test equipment for the job!" Since
he considered the cable scrap and no one had a TDR it didn't really
matter if the cable was destroyed, so I had to show him that it could be
Michael A. Terrell
Go Back To The Cyber-Spy.Com
Usenet Web Archive Index Of
The sci.electronics.design Newsgroup