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Overriding .MODEL paramaters for Trannies.

Is there a way that any one knows of in Ltspice to override a .MODEL of NPN for example, parameter?

I mean something you pick out of the database and drop on the sheet?

For example, the other day some one here was talking about issues with Vbe values and a transistor number was posted that had a Vbeo of 25v.

That got me thinking, so I fired up Ltspice and found that none of the supplied models even set the BvBe.

Evidences makes it clear that dropping a PNP on the sheet and injecting 100V into the base with a 10k R at the emitter to common should make it zener however, all it does is generates 1 uA of current in that emitter R. I would think this would cause a little problem in simulating a circuit if this was ignored? I know it's not good practice to do this however, it sure can lead to a misconception of a working circuit.

So then I tried to insert a spice line and the sim engine does not know what that is because the model I picked was the first pnp at the top of the list and it becomes quite obvious that you can not over ride or insert a parameter value to the selected stock part.

Short of dropping a .model card on the sheet does any one know how to override/insert this?

Something tells me this could be a weakness in the tools...

Jamie

Reply to
Maynard A. Philbrook Jr.
Loading thread data ...

You can edit the line in the

C:\Program Files\LTC\SwCADIII\lib\cmp\standard.bjt

file for that transistor. Or copy/paste into that same file, but rename the part and change parameters. Now you have a new standard transistor. Of course, that will disappear when you update.

As you note, you can paste the line onto your schematic as a .model statement, or put it into a file and include it.

LT Spice doesn't usually include breakdown volages. A 1N914 will happily rectify 100 kilovolts.

--

John Larkin         Highland Technology, Inc 

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com
Reply to
John Larkin

Den torsdag den 11. september 2014 03.41.37 UTC+2 skrev Maynard A. Philbrook Jr.:

you can make a model a version of another model with only some parameters changed with ako (a kind of)

.model 2N7002bv ako:2N7002 BV=60

makes a model called 2N7002bv from the model 2N7002 with the parameter BV set to 60

-Lasse

Reply to
Lasse Langwadt Christensen

The tools is your brain. Therein lies the weakness.

Reply to
John S

You can use shorthand, i.e. AKO (A Kind Of)

.model CrummyNPN AKO:2N3904 BF=4

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

On Wed, 10 Sep 2014 21:41:37 -0400, "Maynard A. Philbrook Jr." Gave us:

You do realize how 'not right' your post header title is, right?

Reply to
DecadentLinuxUserNumeroUno

Maybe add "... two kind of trannies" to this >:-}...

My Own Kind of Hat Alan Jackson

Cowboys and outlaws, right guys and south-paws Good dogs and all kinds of cats. Dirt roads and white lined, and all kinds of stop signs I'll stand right here where I'm at 'Cause I wear my own kind of hat.

There's two kinds of lovers, two kinds of brothers Two kinds of babies to hold. There's two kinds of cherries, two kinds of fairies Two kinds of mothers I'm told I'm told

Cowboys and outlaws, right guys and south-paws Good dogs and all kinds of cats. Dirt roads and white lines and all kinds of stop signs I'll stand right here where I'm at Cause I wear my own kind of hat.

There's two kinds of brother, two kinds of lovers Two kinds of babies to hold There's two kinds of cherries, two kinds of fairies Two kinds of mothers I'm told I'm told

Cowboys and outlaws, right guys and south-paws Good dogs and all kinds of cats. Dirt roads and white lined, and all kinds of stop signs I'll stand right here where I'm at 'Cause I wear my own kind of hat.

ISTR a version that spoke of two kinds of grass ;-) ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| 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.
Reply to
Jim Thompson

On Thu, 11 Sep 2014 08:41:05 -0700, Jim Thompson Gave us:

Great response.

BRL! Type II

Reply to
DecadentLinuxUserNumeroUno

On Thu, 11 Sep 2014 08:41:05 -0700, Jim Thompson Gave us:

I'm all for the good grass... kind.

BRLs all around! (type II of course!)

("BRL!" is my suggested replacement for the worn out "LOL")

It is:

BRL!

BRL!!

(That's type I and type II)

Type I is "Belly Roll Laugh"

Type II is "Bonghit Release Laugh"

Both far better than LOL.

Then, of course... there is "TOMMS"

"That One Made Me Snot!"

Reply to
DecadentLinuxUserNumeroUno 

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| 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.
Reply to
Jim Thompson

This is not really a "LTSpice" issue. Pretty much all Spice vendors just collect models from the web and don't check them, Including me. Its way too much work. The idea is "demo"!

No one should ever use any Spice model for a real project unless they specifically check and modify where necessary, the model to make it agree with the data sheet. A designer needs to take personal responsibility and understand the tools he uses. The designer best knows for his particular application, what particular parameter of a model is most relevant. Any analog designer that can not do basic model development, might probably be better placed flipping burgers at McD.

Kevin Aylward

formatting link
formatting link
- SuperSpice

Reply to
Kevin Aylward

Not to mention that many 1N914 models _do_ include BV...

*$ .model D1N914 D(Is=168.1E-21 N=1 Rs=.1 Ikf=0 Xti=3 Eg=1.11 Cjo=4p
  • M=.3333 Vj=.75 Fc=.5 Isr=100p Nr=2 Bv=100 Ibv=100u Tt=11.54n)
*$

and won't "happily rectify 100 kilovolts". ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| 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.
Reply to
Jim Thompson

In conventional Spice notation it should be...

.model CrummyNPN AKO:2N3904 NPN BF=4

Note the "NPN".

Phil's "shorthand" may work in LTspice (I haven't checked it), but not work in other Spice variants... and parentheses _may_ be required around the parameter(s)...

.model CrummyNPN AKO:2N3904 NPN (BF=4)

good syntax practice, but apparently fading from use in some variants. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| 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.
Reply to
Jim Thompson

Indeed, but see post on n being ~1.9 not 1. Maybe the diodes have been changing over time...

I got this to match quite well for dc with a recent data sheet.

.MODEL d1n914 d(is=4n Rs=500m CJO=2p Tt=5n Bv=100 N=1.9)

Not sure if tranny models is a good thread to get engaged in though...

Kevin Aylward

formatting link
formatting link
- SuperSpice

Reply to
Kevin Aylward

On Thu, 11 Sep 2014 20:16:43 +0100, "Kevin Aylward" Gave us:

Ask Bruce Jenner.

Reply to
DecadentLinuxUserNumeroUno

I think some diode manufacturers are now using implanted junctions rather than diffused.

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| 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.
Reply to
Jim Thompson

I don't think it disappears, I think the update process incorporates your additions.

Cheers

--
Syd
Reply to
Syd Rumpo

Weird. The 2N3904 model is already an NPN. Does it barf if you say

.model TranTran AKO:2N3904 PNP (BF=4) ?

(And the method I posted does work in LTspice.)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

I recall losing some of my personal "standard" parts on an update. I'll check it next time.

I keep a file on the side, my specials, so I can paste them back in.

--

John Larkin         Highland Technology, Inc 

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com
Reply to
John Larkin

Won't barf on the call. But when you try to simulate it'll have a cow about the signs of some parameters which are plus for NPN, minus for PNP.

I wish some people would abstain from mucking with good ol' 2G6 Berkeley Spice syntax.

"Cutesy" confuses the student-level user immensely. (Us old guys have seen every mucked up thing... students haven't.)

...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| 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.
Reply to
Jim Thompson

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