Thanks guys, this was driving me potty last night.
That is weird but yes, it seems very relevant. Hmmm....
Ah... well done
That is weird but yes, it seems very relevant. Hmmm....
Ah... well done
I have another oddity......
A thread on here had me quickly lash up a parallel LM317 supply as per the data sheet example.
Note the output voltage of 16.3 volts.
I now use the 'Duplicate' function and produce this. I delete the .op from the duplicate. It runs OK. Duplicate is the 8th button from the right on the toolbar.
I now alter the copied part by snipping out some parts and altering the configuration. The sim is run and the left hand output voltage is unchanged as it should be.
I now make R14 in the right hand sim a 1000 ohm and run the sim. The left hand output voltage alters dramatically from 16 down to 11 volts.
These are the original files.
Also (whether related or not I don't know...) the sim is one of those that is difficult to converge. Changing input voltage and load can cause it to either take ages to run or effectively never get there.
A thread on here had me quickly lash up a parallel LM317 supply as per the data sheet example.
Note the output voltage of 16.3 volts.
I now use the 'Duplicate' function and produce this. I delete the .op from the duplicate. It runs OK. Duplicate is the 8th button from the right on the toolbar.
I now alter the copied part by snipping out some parts and altering the configuration. The sim is run and the left hand output voltage is unchanged as it should be.
I now make R14 in the right hand sim a 1000 ohm and run the sim. The left hand output voltage alters dramatically from 16 down to 11 volts.
These are the original files.
Also (whether related or not I don't know...) the sim is one of those that is difficult to converge. Changing input voltage and load can cause it to either take ages to run or effectively never get there.
Thanks for trying it
It's a bit weird then if they won't even run under the previous version as a .op
I can't understand why the big change in output voltage on the left hand side when R14 on the right side is altered. Why the interaction between the two halves?
Your image above would be with R14 at 600 ohm I think. I see the same results.
It's a bit weird then if they won't even run under the previous version as a .op
I can't understand why the big change in output voltage on the left hand side when R14 on the right side is altered. Why the interaction between the two halves?
Your image above would be with R14 at 600 ohm I think. I see the same results.
Interesting. Seems somehow the duplication creates a global net between the instances????
At first I thought it was a problem with the LT317A model when a 3rd part model worked fine. But then I re-drew part of the schematic using LT317A again, and then it worked.
A few notes:
1. 45 Volts exceeds the 317 spec of 40 Volts.
2. The LT317A (model?) current limits at 630mA, not 1.5A
3. Powering the op-amp from the output creates a feedback loop which may cause problems.
I saw that original post too, but didn't bother simulating it. I just assumed the vendor did their homework.
At first I thought it was a problem with the LT317A model when a 3rd part model worked fine. But then I re-drew part of the schematic using LT317A again, and then it worked.
A few notes:
1. 45 Volts exceeds the 317 spec of 40 Volts.
2. The LT317A (model?) current limits at 630mA, not 1.5A
3. Powering the op-amp from the output creates a feedback loop which may cause problems.
I saw that original post too, but didn't bother simulating it. I just assumed the vendor did their homework.
Thanks for trying it @steveu
I'm still faffing about with it and have asked over on the LT forum now. No takers as yet In the original sim the value of R14 alters the behaviour as it changes from 984 to 985 ohms. One value gives 16v and the other 11v in the left hand section.
Its one highly flaky sim.
I'm still faffing about with it and have asked over on the LT forum now. No takers as yet
In the original sim the value of R14 alters the behaviour as it changes from 984 to 985 ohms. One value gives 16v and the other 11v in the left hand section.Its one highly flaky sim.
Load the asc file
Start the simulation
Click on 'out_all'
Activate the window with the curve by clicking
In the 'View' menu, select FFT
Click OK with V(out_all)