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another LT Spice question

Started by John Larkin June 13, 2013
Jim Thompson wrote:
> On Fri, 14 Jun 2013 11:14:06 -0700, Joerg <invalid@invalid.invalid> > wrote: > >> Jim Thompson wrote: >>> On Fri, 14 Jun 2013 10:05:24 -0700, Joerg <invalid@invalid.invalid> >>> wrote: >>> >>>> Jim Thompson wrote: >>>>> On Fri, 14 Jun 2013 09:30:27 -0700, Joerg <invalid@invalid.invalid> >>>>> wrote: >>>>> >>>>>> John Larkin wrote: >>>>> [snip] >>>>>>> I often wind up building my own test equipment on my schematic, rather >>>>>>> than doing math. >>>>>>> >>>>>> Same here. Until last week, when I had to start solving equations in >>>>>> complex notation and some only worked if I used letter-A paper sideways >>>>>> and wrote in a very small font. Last time I did that was >>>>>> nineteen-sumpthin, and now that feels like doing 100 push-ups 30 years >>>>>> after boot camp. >>>>> Rather than having to redraw every time, I create symbols that perform >>>>> the various test functions I need, and add them to my personal symbol >>>>> library. >>>>> >>>> Sometimes I do that as well. But not possible on this project. I have to >>>> develop algorithms with which later some highly non-linear sensor >>>> parameter is extracted through a labyrinth of parasitic R's, L's and >>>> C's. All while keeping in mind that the computing horsepower of a PC is >>>> not infinite. >>>> >>>> I could hand it to college kids and they'd probably be faster doing this >>>> sort of math. But that would feel like handing over the steering wheel. >>>> Men don't do that :-) >>> When I encounter non-linear requirements, I usually resort to tables, >>> so my measurement part just calls up a table. >>> >>> (You'll remember my tool that can digitize a graph in a data sheet, >>> straight from the graphics?) >>> >> Yeah, but there ain't no graphics for this here system. > > Do you have an equation? Or a PWL representation? >
Equations, yes. But revealing the architecture would result in a whizzing bullet. No PWL, it's too complex for that. -- Regards, Joerg http://www.analogconsultants.com/
Jim Thompson wrote:
> On Fri, 14 Jun 2013 11:44:32 -0700 (PDT), Klaus Kragelund > <klauskvik@hotmail.com> wrote: > >> On Friday, June 14, 2013 1:22:15 AM UTC+2, John Larkin wrote: > [snip] >>> Too bad there's no integration operator available in the equations. >>> >>> >>> >>> [1] except that it initializes to -250 megavolts. Putting a 1 ohm >>> >>> resistor across the cap fixes that. >>> >> I'm normally using Cadence PSpice. In probe you just write s(var) to integrate. d(var) to differentiate. I suggest you read the manual from start to end, that will save you a lot of time in the future. >> >> If you need the total power, write this in the Measurement Results; YatlastX(s(w(var)))/Max(Time) >> >> Regards >> >> Klaus > > I'm using PSpice as well. LTspice lacks some of the post-processing > bells and whistles that you and I are accustomed to using. >
But it doesn't have the crashes ... [...] -- Regards, Joerg http://www.analogconsultants.com/
On Fri, 14 Jun 2013 12:05:54 -0700, Joerg <invalid@invalid.invalid>
wrote:

>Jim Thompson wrote: >> On Fri, 14 Jun 2013 11:14:06 -0700, Joerg <invalid@invalid.invalid> >> wrote: >> >>> Jim Thompson wrote: >>>> On Fri, 14 Jun 2013 10:05:24 -0700, Joerg <invalid@invalid.invalid> >>>> wrote: >>>> >>>>> Jim Thompson wrote: >>>>>> On Fri, 14 Jun 2013 09:30:27 -0700, Joerg <invalid@invalid.invalid> >>>>>> wrote: >>>>>> >>>>>>> John Larkin wrote: >>>>>> [snip] >>>>>>>> I often wind up building my own test equipment on my schematic, rather >>>>>>>> than doing math. >>>>>>>> >>>>>>> Same here. Until last week, when I had to start solving equations in >>>>>>> complex notation and some only worked if I used letter-A paper sideways >>>>>>> and wrote in a very small font. Last time I did that was >>>>>>> nineteen-sumpthin, and now that feels like doing 100 push-ups 30 years >>>>>>> after boot camp. >>>>>> Rather than having to redraw every time, I create symbols that perform >>>>>> the various test functions I need, and add them to my personal symbol >>>>>> library. >>>>>> >>>>> Sometimes I do that as well. But not possible on this project. I have to >>>>> develop algorithms with which later some highly non-linear sensor >>>>> parameter is extracted through a labyrinth of parasitic R's, L's and >>>>> C's. All while keeping in mind that the computing horsepower of a PC is >>>>> not infinite. >>>>> >>>>> I could hand it to college kids and they'd probably be faster doing this >>>>> sort of math. But that would feel like handing over the steering wheel. >>>>> Men don't do that :-) >>>> When I encounter non-linear requirements, I usually resort to tables, >>>> so my measurement part just calls up a table. >>>> >>>> (You'll remember my tool that can digitize a graph in a data sheet, >>>> straight from the graphics?) >>>> >>> Yeah, but there ain't no graphics for this here system. >> >> Do you have an equation? Or a PWL representation? >> > >Equations, yes. But revealing the architecture would result in a >whizzing bullet. No PWL, it's too complex for that.
You're doing work for the mob ?>:-} ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
Jim Thompson wrote:
> On Fri, 14 Jun 2013 12:05:54 -0700, Joerg <invalid@invalid.invalid> > wrote: > >> Jim Thompson wrote: >>> On Fri, 14 Jun 2013 11:14:06 -0700, Joerg <invalid@invalid.invalid> >>> wrote: >>> >>>> Jim Thompson wrote: >>>>> On Fri, 14 Jun 2013 10:05:24 -0700, Joerg <invalid@invalid.invalid> >>>>> wrote: >>>>> >>>>>> Jim Thompson wrote: >>>>>>> On Fri, 14 Jun 2013 09:30:27 -0700, Joerg <invalid@invalid.invalid> >>>>>>> wrote: >>>>>>> >>>>>>>> John Larkin wrote: >>>>>>> [snip] >>>>>>>>> I often wind up building my own test equipment on my schematic, rather >>>>>>>>> than doing math. >>>>>>>>> >>>>>>>> Same here. Until last week, when I had to start solving equations in >>>>>>>> complex notation and some only worked if I used letter-A paper sideways >>>>>>>> and wrote in a very small font. Last time I did that was >>>>>>>> nineteen-sumpthin, and now that feels like doing 100 push-ups 30 years >>>>>>>> after boot camp. >>>>>>> Rather than having to redraw every time, I create symbols that perform >>>>>>> the various test functions I need, and add them to my personal symbol >>>>>>> library. >>>>>>> >>>>>> Sometimes I do that as well. But not possible on this project. I have to >>>>>> develop algorithms with which later some highly non-linear sensor >>>>>> parameter is extracted through a labyrinth of parasitic R's, L's and >>>>>> C's. All while keeping in mind that the computing horsepower of a PC is >>>>>> not infinite. >>>>>> >>>>>> I could hand it to college kids and they'd probably be faster doing this >>>>>> sort of math. But that would feel like handing over the steering wheel. >>>>>> Men don't do that :-) >>>>> When I encounter non-linear requirements, I usually resort to tables, >>>>> so my measurement part just calls up a table. >>>>> >>>>> (You'll remember my tool that can digitize a graph in a data sheet, >>>>> straight from the graphics?) >>>>> >>>> Yeah, but there ain't no graphics for this here system. >>> Do you have an equation? Or a PWL representation? >>> >> Equations, yes. But revealing the architecture would result in a >> whizzing bullet. No PWL, it's too complex for that. > > You're doing work for the mob ?>:-} >
No, but I live 10 miles west from here: http://www.beachcalifornia.com/hangmans-tree-placerville.html -- Regards, Joerg http://www.analogconsultants.com/
On Fri, 14 Jun 2013 12:07:41 -0700, Joerg <invalid@invalid.invalid>
wrote:

>Jim Thompson wrote: >> On Fri, 14 Jun 2013 11:44:32 -0700 (PDT), Klaus Kragelund >> <klauskvik@hotmail.com> wrote: >> >>> On Friday, June 14, 2013 1:22:15 AM UTC+2, John Larkin wrote: >> [snip] >>>> Too bad there's no integration operator available in the equations. >>>> >>>> >>>> >>>> [1] except that it initializes to -250 megavolts. Putting a 1 ohm >>>> >>>> resistor across the cap fixes that. >>>> >>> I'm normally using Cadence PSpice. In probe you just write s(var) to integrate. d(var) to differentiate. I suggest you read the manual from start to end, that will save you a lot of time in the future. >>> >>> If you need the total power, write this in the Measurement Results; YatlastX(s(w(var)))/Max(Time) >>> >>> Regards >>> >>> Klaus >> >> I'm using PSpice as well. LTspice lacks some of the post-processing >> bells and whistles that you and I are accustomed to using. >> > >But it doesn't have the crashes ... > >[...]
PSpice, and other excellent softwares, only crash for you >:-} The ONLY thing I ever have problems with is Firefox and its plug-in container, though the latest release seems to have fixed that. ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
Jim Thompson wrote:
> On Fri, 14 Jun 2013 12:07:41 -0700, Joerg <invalid@invalid.invalid> > wrote: > >> Jim Thompson wrote: >>> On Fri, 14 Jun 2013 11:44:32 -0700 (PDT), Klaus Kragelund >>> <klauskvik@hotmail.com> wrote: >>> >>>> On Friday, June 14, 2013 1:22:15 AM UTC+2, John Larkin wrote: >>> [snip] >>>>> Too bad there's no integration operator available in the equations. >>>>> >>>>> >>>>> >>>>> [1] except that it initializes to -250 megavolts. Putting a 1 ohm >>>>> >>>>> resistor across the cap fixes that. >>>>> >>>> I'm normally using Cadence PSpice. In probe you just write s(var) to integrate. d(var) to differentiate. I suggest you read the manual from start to end, that will save you a lot of time in the future. >>>> >>>> If you need the total power, write this in the Measurement Results; YatlastX(s(w(var)))/Max(Time) >>>> >>>> Regards >>>> >>>> Klaus >>> I'm using PSpice as well. LTspice lacks some of the post-processing >>> bells and whistles that you and I are accustomed to using. >>> >> But it doesn't have the crashes ... >> >> [...] > > PSpice, and other excellent softwares, only crash for you >:-} >
Oh no. I remember lots of others, including some here in the NG. At one point when it got really bad I had the support guys on the phone and allowed them desktop access via web. Showed them the crashes, more and more folks came in on their side. They checked lots of settings, all ok, then commended me on how clean my PC was. I guess they must see a lot of messy ones. Then someone in the background exclaimed "I can't believe this is happening!". To avoid any misunderstandings, the support was excellent. The quality of the software was IMHO not. You probably have an older version with less problems. With software it's usually like with red wine, older = better.
> The ONLY thing I ever have problems with is Firefox and its plug-in > container, though the latest release seems to have fixed that. >
Yep, that plug-in container is a really buggy piece of software. Yet still, for me it crashes with a runtime error maybe 4-5 times a year. That is absolutely nothing compared to Orcad/PSpice and Acrobat Reader. Both of which I ditched -> problem solved. Skype must have been fixed, that no longer crashes since the last update. It leaves the occasional turd on the bottom task bar but one can live with that. It's IMHO not nearly as good as GoToMeeting though, so that's what gets used mostly here. -- Regards, Joerg http://www.analogconsultants.com/
On Fri, 14 Jun 2013 12:25:56 -0700, Joerg <invalid@invalid.invalid>
wrote:

>Jim Thompson wrote: >> On Fri, 14 Jun 2013 12:07:41 -0700, Joerg <invalid@invalid.invalid> >> wrote: >> >>> Jim Thompson wrote: >>>> On Fri, 14 Jun 2013 11:44:32 -0700 (PDT), Klaus Kragelund >>>> <klauskvik@hotmail.com> wrote: >>>> >>>>> On Friday, June 14, 2013 1:22:15 AM UTC+2, John Larkin wrote: >>>> [snip] >>>>>> Too bad there's no integration operator available in the equations. >>>>>> >>>>>> >>>>>> >>>>>> [1] except that it initializes to -250 megavolts. Putting a 1 ohm >>>>>> >>>>>> resistor across the cap fixes that. >>>>>> >>>>> I'm normally using Cadence PSpice. In probe you just write s(var) to integrate. d(var) to differentiate. I suggest you read the manual from start to end, that will save you a lot of time in the future. >>>>> >>>>> If you need the total power, write this in the Measurement Results; YatlastX(s(w(var)))/Max(Time) >>>>> >>>>> Regards >>>>> >>>>> Klaus >>>> I'm using PSpice as well. LTspice lacks some of the post-processing >>>> bells and whistles that you and I are accustomed to using. >>>> >>> But it doesn't have the crashes ... >>> >>> [...] >> >> PSpice, and other excellent softwares, only crash for you >:-} >> > >Oh no. I remember lots of others, including some here in the NG. At one >point when it got really bad I had the support guys on the phone and >allowed them desktop access via web. Showed them the crashes, more and >more folks came in on their side. They checked lots of settings, all ok, >then commended me on how clean my PC was. I guess they must see a lot of >messy ones. Then someone in the background exclaimed "I can't believe >this is happening!". > >To avoid any misunderstandings, the support was excellent. The quality >of the software was IMHO not. > >You probably have an older version with less problems. With software >it's usually like with red wine, older = better. > > >> The ONLY thing I ever have problems with is Firefox and its plug-in >> container, though the latest release seems to have fixed that. >> > >Yep, that plug-in container is a really buggy piece of software. Yet >still, for me it crashes with a runtime error maybe 4-5 times a year. >That is absolutely nothing compared to Orcad/PSpice and Acrobat Reader. >Both of which I ditched -> problem solved. > >Skype must have been fixed, that no longer crashes since the last >update. It leaves the occasional turd on the bottom task bar but one can >live with that. It's IMHO not nearly as good as GoToMeeting though, so >that's what gets used mostly here.
I have v15.7, which is just a few versions back. The crash difference is that you, and other crashees, are using OrCAD Crapture, but I am still using original crispy flavor PSpice Schematics, which is rock solid. ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
Jim Thompson wrote:
> On Fri, 14 Jun 2013 12:25:56 -0700, Joerg <invalid@invalid.invalid> > wrote: > >> Jim Thompson wrote:
[...]
>> >>> The ONLY thing I ever have problems with is Firefox and its plug-in >>> container, though the latest release seems to have fixed that. >>> >> Yep, that plug-in container is a really buggy piece of software. Yet >> still, for me it crashes with a runtime error maybe 4-5 times a year. >> That is absolutely nothing compared to Orcad/PSpice and Acrobat Reader. >> Both of which I ditched -> problem solved. >> >> Skype must have been fixed, that no longer crashes since the last >> update. It leaves the occasional turd on the bottom task bar but one can >> live with that. It's IMHO not nearly as good as GoToMeeting though, so >> that's what gets used mostly here. > > I have v15.7, which is just a few versions back. The crash difference > is that you, and other crashees, are using OrCAD Crapture, but I am > still using original crispy flavor PSpice Schematics, which is rock
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> solid. >
That is what I meant with older. Nowadays a network simulator requires a schematic capture front-end. I determine my impression from the quality of the _available_ product in its entirety. To me there is no excuse such as "Oh, but ... but ... it's just the engine controller that always has issues". -- Regards, Joerg http://www.analogconsultants.com/
On Fri, 14 Jun 2013 12:36:43 -0700, Joerg <invalid@invalid.invalid>
wrote:

>Jim Thompson wrote: >> On Fri, 14 Jun 2013 12:25:56 -0700, Joerg <invalid@invalid.invalid> >> wrote: >> >>> Jim Thompson wrote: > >[...] > >>> >>>> The ONLY thing I ever have problems with is Firefox and its plug-in >>>> container, though the latest release seems to have fixed that. >>>> >>> Yep, that plug-in container is a really buggy piece of software. Yet >>> still, for me it crashes with a runtime error maybe 4-5 times a year. >>> That is absolutely nothing compared to Orcad/PSpice and Acrobat Reader. >>> Both of which I ditched -> problem solved. >>> >>> Skype must have been fixed, that no longer crashes since the last >>> update. It leaves the occasional turd on the bottom task bar but one can >>> live with that. It's IMHO not nearly as good as GoToMeeting though, so >>> that's what gets used mostly here. >> >> I have v15.7, which is just a few versions back. The crash difference >> is that you, and other crashees, are using OrCAD Crapture, but I am >> still using original crispy flavor PSpice Schematics, which is rock > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ >> solid. >> > >That is what I meant with older. Nowadays a network simulator requires a >schematic capture front-end. I determine my impression from the quality >of the _available_ product in its entirety. To me there is no excuse >such as "Oh, but ... but ... it's just the engine controller that always >has issues".
"Older" has nothing to do with it, except for the very latest version where they scuttled any use of PSpice Schematics. At every "update" I insisted on PSpice Schematics as the GUI. So did many others. When they finally refused, we all refused to update and pay the fees. You're probably working with wusses where the management ordered the use of Crapture >:-} ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
On Thu, 13 Jun 2013 20:34:23 -0700, miso wrote:

> I don't know if it matters in your analysis, but spice doesn't conserve > charge.
What gave you that idea? Try this. A 1 farad capacitor, in series with 1 ohm (external, not LT's parasitic, turn all those off, charged by a one second 1 volt pulse, and allowed to discharge when the voltage source goes to zero. Give it enough time to fully discharge, 20 seconds is about right. Integrate the current in the capacitor, you'll find it integrates to zero. That's conservation of charge. I just did it, with LTspice. With a 10 microsecond max timestep, the discrepancy is a few femtocoulombs. Spice wouldn't be much use if it didn't conserve both charge and energy. What might make people think otherwise is LTspice's annoying habit of supplying parasitic properties by default. Berkeley doesn't do that. -- "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)