Getting a TL072 LTSpice subckt to work
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Zoldar71 3 months ago
Hi, I'm reading up on the tutorial of spice simulation and I'm at the part where it is explained how to use an external LTSpice model. I try to repeat the steps in the tutorial for a TL072 op amp. [https://oshwlab.com/Zoldar71/create-spice-model-of-tl072](https://oshwlab.com/Zoldar71/create-spice-model-of-tl072)<br> <br> When running the simulation I get the following error 'The circuit has components without simulation model: dx'. I pasted the AD817 spice model text from the tutorial example in the schema and changed the op amp symbol name to AD817. Now the simulation runs fine. I can see that the TL072 subckt uses a dx model, but the AD817 subckt also uses a dx model. What am I overlooking? Cheers, Martin
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andyfierman 3 months ago
Sorry but I cannot reproduce your problem. If I make a copy of your simulation schematic: and then: rename the TL072 symbol to AD817 and then; set the TL072 subckt to Comment; set the AD817 netlist to Spice; or: rename the TL072 symbol to AD817 and then; set the TL072 and AD817 subckts to Comment; or: rename the TL072 symbol to AD817 and then; delete both the TL072 and AD817 netlists then the sim runs fine. * Please note that you do not need to paste the AD817 subckt in from Analog Devices. There is already a copy of it in the EasyEDA (and not the LTspice built-in) library.
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Zoldar71 3 months ago
@andyfierman: Hi, Andy thank you for your time. I guess I was not clear in my question. It is the TL072 subckt I want to get running. When it was not working and gave the error, I added the AD817 subckt as a way of debugging, because I noticed that this subckt uses the DX model too. I updated my project. Changed the AD817 txt to comment and ran the simulation. Same error. ![Schermafbeelding 2021-01-22 232115.png](//image.easyeda.com/pullimage/cYKPLeoJmWmJrFCQZMoRTxCZH41VEc6ODbnEHUYZ.png)
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andyfierman 3 months ago
I should have said that I  girst ran your sim with the symbol name as TL072  and the TL072 subckt text type set to spice and that ran ok too. Can you post a sim with just the circuit with only the TL072 subckt in it and share that in the same osh project? I'll try running that and see what happens. I don't understand why you see the warning about dx because that is a diode whose model is defined inside the TL072 subckt.
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andyfierman 3 months ago
girst = first
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Zoldar71 3 months ago
I found what is wrong. (Through you pointers). The problem is, that I previously tried to model the TL072 as described in one of the easy eda video tutorials. Creating a component in my workspace and pasting the spice model in there. I couldn't get it to work, but the 'broken' component was still in my Workspace in the spice library. So I guess the subckts in the library take precedence over the ones in the schema (probably something I missed in the help). I found out because I renamed the TL072 to TL072_mvl in the symbol and the subckt text. And then it ran fine. Now I have this done, I try the first route again to create a component in my workspace to use in my further projects. Thanks Andy.
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Zoldar71 3 months ago
Now I created the TL072 spice model in my workspace successfully.
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andyfierman 3 months ago
@Zoldar71 Good news. Well done. :)
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