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LTSpice anomaly. Same wire, different voltages.
LTSpice anomaly. Same wire, different voltages.
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Old 1st February 2013, 10:53 AM   #21
Elvee is offline Elvee  Belgium
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I don't have the issue, whether in op or tran: it always shows the correct voltage of 7.33 something everywhere on the net.

It probably has to do with this:
A simulation free zone. Design it, build it, test it.

He somewhats knows you don't like him, so he doesn't like you.

More seriously, this kind of things can happen for legitimate reasons: if you make a change after a sim, or if a change is pending before you start the sim, etc.

Depending on the configuration, the fluke could be saved in the asc and be presented again as it is in some cases.
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Old 1st February 2013, 10:57 AM   #22
Rundmaus is offline Rundmaus  Germany
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Maybe things like this happen in the turbulent weather zone where 'A simulation free zone.' (Design it, build it, test it.) and SPICE (the mother of all circuit simulators) collide...

*scnr*
Rundmaus

EDIT: Elvee was seconds faster than me - damn!
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Old 1st February 2013, 11:04 AM   #23
wintermute is offline wintermute  Australia
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LTSpice anomaly. Same wire, different voltages.
Hi Elvee, were you just hovering (it shows the correct voltage if you do) or did you click and add a label? It is after clicking and adding the upper label that it goes wacky for me. after that voltages all over the circuit seem to go haywire.

Tony.
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Old 1st February 2013, 12:22 PM   #24
Elvee is offline Elvee  Belgium
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Quote:
Originally Posted by wintermute View Post
Hi Elvee, were you just hovering (it shows the correct voltage if you do) or did you click and add a label? It is after clicking and adding the upper label that it goes wacky for me. after that voltages all over the circuit seem to go haywire.

Tony.
You may not measure a node (any node) after you relabel something: everything is changed and reordered, and the old voltages have no relation with the present nodes numbering.

Ideally, I think LTspice should gray-out these options as soon as something is changed.

If you want to do that kind of thing, labelling the nodes of interest with non-standard names, like A, B, Out, In are the way to go.
Otherwise, LTspice doesn't track the node names (and anyway, if you want to be general and complete, how would you do that, when you split a net for instance: which one inherits of the original title?)
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Old 1st February 2013, 12:32 PM   #25
jan.didden is offline jan.didden  Europe
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Does that mean that when you do a relabel and then rerun the sim that all is OK again?

jan
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Old 1st February 2013, 12:41 PM   #26
Mooly is offline Mooly  United Kingdom
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LTSpice anomaly. Same wire, different voltages.
Quote:
Originally Posted by Elvee View Post
It probably has to do with this:
A simulation free zone. Design it, build it, test it.
Probably

Quote:
Originally Posted by Rundmaus View Post


Maybe things like this happen in the turbulent weather zone where 'A simulation free zone.' (Design it, build it, test it.) and SPICE (the mother of all circuit simulators) collide...
I know I know... new sig line required

-----------------------------------------------------------------------------------------

I have done a fair bit of editing and did keep saving the file as it all progressed but it still seems a bizarre issue to me. I did flip the IC (to make it look neater) by chopping all the connections and then rotating it and connecting back up again.

Might have a couple of ideas to try later...
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Old 1st February 2013, 01:29 PM   #27
Mooly is offline Mooly  United Kingdom
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LTSpice anomaly. Same wire, different voltages.
Another circuit done weeks (months ?) ago. Its a similar circuit concept (yet totally different as you can see) and yet it exhibits the same error and node changing.
Attached Images
File Type: jpg New Anomaly 1.JPG (71.4 KB, 41 views)
File Type: jpg New Anomaly 2.JPG (65.6 KB, 40 views)
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Old 2nd February 2013, 06:10 AM   #28
wintermute is offline wintermute  Australia
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LTSpice anomaly. Same wire, different voltages.
It seems that the placing of the "labels" that show the operating point at that place in the circuit is broken. But running the sim again fixes them and they show the right voltage. I would say it is a bug, but maybe it is "working as designed".

Tony.
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Old 2nd February 2013, 06:35 AM   #29
Mooly is offline Mooly  United Kingdom
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LTSpice anomaly. Same wire, different voltages.
I never tried that, running it again after tagging the lines. Your right, they do change to back to the correct data, both voltage and nodes.
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Old 2nd February 2013, 07:38 AM   #30
powerflux is offline powerflux  Netherlands
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Quote:
Originally Posted by Mooly View Post
I never tried that, running it again after tagging the lines. Your right, they do change to back to the correct data, both voltage and nodes.
it's not a bug, that's the way ltspice does it. The waveforms (and all node voltages) are stored after a run. If you've made changes but never ran the simulation again, these voltages and waveforms will reflect the old situation.

combine this with what Elvee said: there's your "problem".
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