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Old 24th October 2007, 03:27 AM   #361
jcx is offline jcx  United States
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I've tried creating an automatic fundamental nulling circuit for LtSpice:
Click the image to open in full size.

comments from the Fundamental_Null.asc (included in zip):

Fundamental_Null Distortion Residual viewing tool

requires Fundamental_Null.asy ( may be put in \lib\sym\Misc )
requires Fundamental_Null.asc ( same path as .asc calling the tool )

at top level declare:
.param period=nn, ncycles=mm
.tran 0 {ncycles*period} 0 {period/1e4}
.option plotwinsize=0
use stimulus Vsource sin(0 xx {1/period})

Automatically calculates amplitude and phase of fundamental of length {period}
of signal connected to pos_in, minus_in
using the 3rd from last cycle of {ncycles}
Subtracts fundamental and average DC component found in 3rd from last {ncycles}
from last 2 cycles for display at null_out
Attached Files
File Type: zip distortion_residual.zip (2.9 KB, 202 views)
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Old 24th October 2007, 10:08 PM   #362
KSTR is offline KSTR  Germany
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Excellent! I checked with signals with known distortion components, works flawless.

- Klaus
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Old 26th October 2007, 10:14 AM   #363
marus is offline marus  Romania
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Hi,

I think SPICE simulations it's a good thing. My favorite it's Orcad PSpice.
The most frequent problem that I encounter is, of course, that I don't find all the components that I need.
For example : I started an amplifier schematics and I don't find 2SD669/2SB649 transistors.
It is posible that WE ( the users of this program ) can create the components that we need from datasheet ? Because if we don't it's useless.
If anyone knows how to do that pleaseeeee let me know.
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Old 26th October 2007, 09:45 PM   #364
x-pro is offline x-pro  United Kingdom
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Default Thanks

to Andy for providing 2SK1530 model here - it did allow me to get a nice result in my output stage simulation:

http://www.diyaudio.com/forums/showt...01#post1335401

Cheers

Alex
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Old 28th October 2007, 03:43 AM   #365
PB2 is offline PB2  United States
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OnSemi models for MJE171 and 181 seem to be defective, anyone have good ones?

TIA,
Pete B.
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Old 28th October 2007, 11:13 AM   #366
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I'm working to make the approach of andy_c more usable.
However I'm encountering some problems ...
The main problem is that the function to be minimized has so many fake minima that it's realy hard, once reached a solution, to say that is the best solution or, at least, a good solution.
The methodology I have depicted seems to give some good and stable solution. By "good" I mean a solution that fits well the specifications sheet data, by "stable" I mean a solution that stays the same even if the initial, guess, parameters are slightly changed.
Click the image to open in full size.
Unfortunately, for the MJE1302 I get (for the static parameters) values
+IS=2.683E-9
+BF=286.774
+NF=1.323
+VAF=119.762
+IKF=10.525
+ISE=9.803E-11
+NE=1.475
+BR=0.5
+NR=1.09511
+VAR=58.672
+IKR=0.3
+ISC=1E-13
+RB=2.237
different from the ones proposed by andy_c.
In LTSpice I see some sort of discontinuity at 80A, even if if this discontinuity is not there in PSPICE:
Click the image to open in full size.
So, my question is: at what condition a solution is a good solution ? is there any "sanity check" to apply ?
Thanks
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Old 28th October 2007, 01:33 PM   #367
PB2 is offline PB2  United States
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Quote:
Originally posted by teodorom
I'm working to make the approach of andy_c more usable.
However I'm encountering some problems ...
The main problem is that the function to be minimized has so many fake minima that it's realy hard, once reached a solution, to say that is the best solution or, at least, a good solution.
The methodology I have depicted seems to give some good and stable solution. By "good" I mean a solution that fits well the specifications sheet data, by "stable" I mean a solution that stays the same even if the initial, guess, parameters are slightly changed.
Click the image to open in full size.
Unfortunately, for the MJE1302 I get (for the static parameters) values
+IS=2.683E-9
+BF=286.774
+NF=1.323
+VAF=119.762
+IKF=10.525
+ISE=9.803E-11
+NE=1.475
+BR=0.5
+NR=1.09511
+VAR=58.672
+IKR=0.3
+ISC=1E-13
+RB=2.237
different from the ones proposed by andy_c.
In LTSpice I see some sort of discontinuity at 80A, even if if this discontinuity is not there in PSPICE:
Click the image to open in full size.
So, my question is: at what condition a solution is a good solution ? is there any "sanity check" to apply ?
Thanks
I've been casually looking at models due to the fact that so many seem to have issues from OnSemi. This document seems to be helpful have you seen it before?
http://www.intusoft.com/lit/WkwModels.pdf

Pete B.
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Old 28th October 2007, 01:43 PM   #368
PB2 is offline PB2  United States
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I've seen some medium power transistors (OnSemi MJE243/253) with 100 to 400 ohm values for RB. From that document, page 32:
"Beware of device models that contain large (> 10 Ohms) values for RB without the specification of IRB and RBM. Their small signal behavior may be correct, but they will be incorrectly biased.

Pete B.
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Old 28th October 2007, 01:46 PM   #369
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Thank you. Me I have used also
http://eesof.tm.agilent.com/docs/icc...on/GP_DOCU.pdf
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Old 28th October 2007, 09:01 PM   #370
PB2 is offline PB2  United States
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That looks very good, thanks! Pete B.
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