LTSpice anomaly. Same wire, different voltages. - Page 2 - diyAudio
Go Back   Home > Forums > Design & Build > Software Tools

Software Tools SPICE, PCB CAD, speaker design and measurement software, calculators

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 1st February 2013, 06:55 AM   #11
diyAudio Member
 
Rundmaus's Avatar
 
Join Date: Aug 2005
Using the node highlight function, try to find out which parts of the circuit belong to the two nodes N023 and N032 - maybe that shows why LTSpice is confusing them...

EDIT: If you don't want to rely on the graphic interface, check the netlist file created by the schematic editor for the entries of N023 and N032 and find out where the two nodes are in the circuit.

Last edited by Rundmaus; 1st February 2013 at 07:04 AM.
  Reply With Quote
Old 1st February 2013, 06:58 AM   #12
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
"Node highlight" ?

I've never used that and as a Spice newbie I'll have to look at how to do that.
__________________
-------------------------------------------------------
A simulation free zone. Design it, build it, test it.
  Reply With Quote
Old 1st February 2013, 07:05 AM   #13
diyAudio Member
 
Rundmaus's Avatar
 
Join Date: Aug 2005
If a 'Newbie' anyway, better to learn the 'good' way and have a look at the netlist file!

EDIT: Just had a look at the LTSpice schematic editor and it does not seem to be able to higlight nodes. If you look at the netlist file (open the file using a text editor or let LTSpice show the netlist via the menu entry), you will find a line for each component:

[component name] [connection1] ... [connection n] [component properties]

Now look for N023 and N032 and check in the schematic to which components these two nodes are connected.

Last edited by Rundmaus; 1st February 2013 at 07:15 AM.
  Reply With Quote
Old 1st February 2013, 07:13 AM   #14
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Node 23 seems to be the emitter of Q7. When I tag the opamp line this node changes to from node 23 to node 24 !

Quote:
Originally Posted by Rundmaus View Post
If a 'Newbie' anyway, better to learn the 'good' way and have a look at the netlist file!
__________________
-------------------------------------------------------
A simulation free zone. Design it, build it, test it.
  Reply With Quote
Old 1st February 2013, 07:18 AM   #15
diyAudio Member
 
Rundmaus's Avatar
 
Join Date: Aug 2005
Quote:
Originally Posted by Mooly View Post
Node 23 seems to be the emitter of Q7. When I tag the opamp line this node changes to from node 23 to node 24 !
This hints at a problem with the schematic editor / user interface - the netlist is determined by the schematic and does not change unless you change the schematic, i.e. not by clicking/tagging anything. Looks as if the tagging function randomly selects wrong nodes when clicking anything.

Looking into the netlist will clear things up I hope.
  Reply With Quote
Old 1st February 2013, 07:20 AM   #16
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Thanks... I'll have a look later today when I have more time
__________________
-------------------------------------------------------
A simulation free zone. Design it, build it, test it.
  Reply With Quote
Old 1st February 2013, 09:04 AM   #17
just another
diyAudio Moderator
 
wintermute's Avatar
 
Join Date: Aug 2003
Location: Sydney
Blog Entries: 22
Definitely looks like a bug to me!!! It shows 7V when I hover over any point on that line. If I click on the lower part it puts 7V If I then click on the upper part, it puts 34mV (and the lower one changes from 7V to 34mV.

I deleted the two tags and did it again. this time it started with 7V and then when I clicked above it got -652mV... (for both places) very odd!!

and yes node 023 is the emitter of Q7!!

I tried dragging R29 to show that there were no breaks in the line, and now I cannot get a tag anywhere on that non-straight line it just gives ???! I suspect that there is a bug in the interface that is not properly picking up the co-ordinates of the mouse when you click to add the tag. It is certainly reproducable with the model you have attached though, so should make things easy to report if you want to do a bug report!

edit: I did it one more time and this time it was -2.32V and node 022 which I think should be the -ve input of the opamp which it is now showing at 7V and node N032!! It seems this time it has swapped the negative input and the output!

Tony.
Attached Images
File Type: png bug.png (3.0 KB, 39 views)
File Type: png bug2.png (3.3 KB, 38 views)
File Type: png bug3.png (4.7 KB, 37 views)
File Type: png bug4.png (10.6 KB, 36 views)
File Type: png bug5.png (4.9 KB, 37 views)
__________________
Any intelligence I may appear to have is purely artificial!
Some of my photos

Last edited by wintermute; 1st February 2013 at 09:13 AM. Reason: add 4th pic
  Reply With Quote
Old 1st February 2013, 10:15 AM   #18
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Great City of Turnhout, Belgium
Blog Entries: 7
Well where is V(n23) in the schematic?

jan
__________________
I won't make the tactical error to try to dislodge with rational arguments a conviction that is beyond reason - Daniel Dennett
Check out Linear Audio Vol 7!
  Reply With Quote
Old 1st February 2013, 10:22 AM   #19
just another
diyAudio Moderator
 
wintermute's Avatar
 
Join Date: Aug 2003
Location: Sydney
Blog Entries: 22
The answer to that is "it depends" when there are no tags it is where it is supposed to be. But when The tags are in place (at least the last one I did) it changed to N024!!!!

Tony.
__________________
Any intelligence I may appear to have is purely artificial!
Some of my photos
  Reply With Quote
Old 1st February 2013, 10:35 AM   #20
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Thanks for trying it Tony. Good to see its reproducible.

I'm a bit short on time today to try things on it but it does seem like a bug to me.
__________________
-------------------------------------------------------
A simulation free zone. Design it, build it, test it.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Phasing/soundtage anomaly Puffin Multi-Way 10 25th November 2012 09:50 PM
Redplating anomaly? dgta Tubes / Valves 18 29th October 2011 05:43 AM
JustMLS impedance anomaly Mos Fetish Multi-Way 0 6th March 2007 01:00 AM
LL1660S Anomaly arnoldc Tubes / Valves 17 3rd May 2006 01:00 AM
TAD TL-1102 response anomaly? Alidore Multi-Way 0 27th January 2004 04:54 AM


New To Site? Need Help?

All times are GMT. The time now is 10:23 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2