If you had one what would you use it for
in [Design]
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From: Jim Thompson on 21 Oct 2009 19:10 On Wed, 21 Oct 2009 16:04:45 -0700, Joerg <invalid(a)invalid.invalid> wrote: >Jim Thompson wrote: >> On Wed, 21 Oct 2009 14:08:25 -0700, Joerg <invalid(a)invalid.invalid> >> wrote: >> >>> John Larkin wrote: >>>> On Wed, 21 Oct 2009 06:21:02 -0700 (PDT), MooseFET >>>> <kensmith(a)rahul.net> wrote: >>>> >>>>> Imagine you had a sensor that could measure very small magnetic >>>>> fields. It measures with a noise floor of about 0.1fT. Unfortunately >>>>> the band width is only a few hundred Hz and it only works inside a >>>>> shield. >>>>> >>>>> What would you use such a sensor for? The best I've thought of is >>>>> detecting the flow of current in a PCB to find a short circuit. >>>> You need high spatial resolution for a general-purpose board short >>>> finder. Magnetically, you can do it with a pulsed current source and a >>>> really tiny ferrite-core pickup coil. I do it lately with a DC source >>>> and a thermal imager, so you can *see* the current path. >>>> >>> If you crank up the DC current some more you can see the short without >>> the FLIR camera. If you crank it up even more the short may fix itself >>> but you'd have to open the windows for a while. >> >> In the early '70's I used to have pin hole problems with Alumina >> substrates, the screened-on metalization would go thru a pin hole and >> short a trace to ground plane on the back-side. >> >> You take a 6V/100A power supply... "click" ;-) >> > >Sometimes when in a ham radio contest and the plates of the notoriously >under-dimensioned output side variable caps fused together I'd >occasionally key the transmitter CW at full legal limit ... tunggg ... >*PHOOMP* ... problem fixed, some ozone and weld shop smell wafting >through the air. Reminds of this morning, put the grandson on the school bus, breeze was such that I could smell fumes from the exhaust... very much like Clorox??? Anyone know diesels, and why/how such a smell? ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | Cranky Old Git With Engineering Mind Faster Than a Speeding Prissy
From: Joerg on 21 Oct 2009 19:24 Jim Thompson wrote: > On Wed, 21 Oct 2009 16:04:45 -0700, Joerg <invalid(a)invalid.invalid> > wrote: > >> Jim Thompson wrote: >>> On Wed, 21 Oct 2009 14:08:25 -0700, Joerg <invalid(a)invalid.invalid> >>> wrote: >>> >>>> John Larkin wrote: >>>>> On Wed, 21 Oct 2009 06:21:02 -0700 (PDT), MooseFET >>>>> <kensmith(a)rahul.net> wrote: >>>>> >>>>>> Imagine you had a sensor that could measure very small magnetic >>>>>> fields. It measures with a noise floor of about 0.1fT. Unfortunately >>>>>> the band width is only a few hundred Hz and it only works inside a >>>>>> shield. >>>>>> >>>>>> What would you use such a sensor for? The best I've thought of is >>>>>> detecting the flow of current in a PCB to find a short circuit. >>>>> You need high spatial resolution for a general-purpose board short >>>>> finder. Magnetically, you can do it with a pulsed current source and a >>>>> really tiny ferrite-core pickup coil. I do it lately with a DC source >>>>> and a thermal imager, so you can *see* the current path. >>>>> >>>> If you crank up the DC current some more you can see the short without >>>> the FLIR camera. If you crank it up even more the short may fix itself >>>> but you'd have to open the windows for a while. >>> In the early '70's I used to have pin hole problems with Alumina >>> substrates, the screened-on metalization would go thru a pin hole and >>> short a trace to ground plane on the back-side. >>> >>> You take a 6V/100A power supply... "click" ;-) >>> >> Sometimes when in a ham radio contest and the plates of the notoriously >> under-dimensioned output side variable caps fused together I'd >> occasionally key the transmitter CW at full legal limit ... tunggg ... >> *PHOOMP* ... problem fixed, some ozone and weld shop smell wafting >> through the air. > > Reminds of this morning, put the grandson on the school bus, breeze > was such that I could smell fumes from the exhaust... very much like > Clorox??? Anyone know diesels, and why/how such a smell? > IMHO sloppy design/fabrication. Domestic bus engine mfgs need a serious dose of education. I find it rather odd that states slap all sorts of extreme smog regs on cars while school buses can just keep belching out dirt. Probably the quality of Diesel in the US ain't that great either but that's no excuse, the Setra buses from Germany I've seen here didn't belch stuff and did not smell. They were huge tour buses and run on the same Diesel as the school buses. So it can be done. I just finished an injector design (but for aerospace). Initially I was looking for dedicated chips. What I found was very archaic and some app note circuits almost made me sick. So I rolled my own, much better precision than the, ahem, "professional" solutions of the trade. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Joerg on 21 Oct 2009 19:25 Rich Grise wrote: > On Wed, 21 Oct 2009 15:15:40 +0000, Jan Panteltje wrote: >> On a sunny day (Wed, 21 Oct 2009 06:21:02 -0700 (PDT)) it happened MooseFET >>> Imagine you had a sensor that could measure very small magnetic >>> fields. It measures with a noise floor of about 0.1fT. Unfortunately >>> the band width is only a few hundred Hz and it only works inside a >>> shield. >>> >>> What would you use such a sensor for? The best I've thought of is >>> detecting the flow of current in a PCB to find a short circuit. >> Brain current imaging? > > Detecting emotional response to situations, like a lie detector, a la GSR > (Galvanic Skin Response) meters. > http://en.wikipedia.org/wiki/Galvanic_skin_response > A much better method had been invented in 1883: http://en.wikipedia.org/wiki/Pinocchio -- SCNR, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Fred Bartoli on 21 Oct 2009 19:33 Joerg a �crit : > Rich Grise wrote: >> On Wed, 21 Oct 2009 15:15:40 +0000, Jan Panteltje wrote: >>> On a sunny day (Wed, 21 Oct 2009 06:21:02 -0700 (PDT)) it happened >>> MooseFET >>>> Imagine you had a sensor that could measure very small magnetic >>>> fields. It measures with a noise floor of about 0.1fT. Unfortunately >>>> the band width is only a few hundred Hz and it only works inside a >>>> shield. >>>> >>>> What would you use such a sensor for? The best I've thought of is >>>> detecting the flow of current in a PCB to find a short circuit. >>> Brain current imaging? >> >> Detecting emotional response to situations, like a lie detector, a la GSR >> (Galvanic Skin Response) meters. >> http://en.wikipedia.org/wiki/Galvanic_skin_response >> > > A much better method had been invented in 1883: > > http://en.wikipedia.org/wiki/Pinocchio > Good one! -- Thanks, Fred.
From: Tim Williams on 21 Oct 2009 19:55
On Oct 21, 6:10 pm, Jim Thompson <To-Email-Use-The-Envelope-I...(a)My- Web-Site.com> wrote: > Reminds of this morning, put the grandson on the school bus, breeze > was such that I could smell fumes from the exhaust... very much like > Clorox??? Anyone know diesels, and why/how such a smell? Not chlorine, NO2. Running lean, I would suppose. Excess O2 and hot combustion burns a little N2. No cat = NOx and unburned hydrocarbons pass through unadulterated, hence the belch of soot on takeoff as well. I would guess they use a very old engine design. Maybe one with fuel control instead of throttle (hence the huge span of mixture). Oxygen sensor, engine computer? Who needs 'em. Tim |