Installing and using LTspice IV (now including LTXVII), From beginner to advanced

[Mooly]

Thanks all 🙂
I find all the myriad default models more a hindrance than a help which is why I have things set up this way with a very limited set of models directly available. If I want a specific model I just paste it into the appropriate file. I've done the same for diodes and also J and MOS fet's.

 

[triode_al]

I have several 2SK1020 in my bin. I can't find a Spice model. As an equivalent, the IRF460 is named.
Does anyone have an idea how to get a model?

 

[triode_al]

Some time back I posted some templates I'd made for making distortion measurements using LTspice. Last time I looked, seven people had downloaded them and presumably looked at them. That's almost eight!

So, here is a more complete and refined collection. In addition to the usual harmonic distortion test from a single sine wave source, pretty much all of the dual tone, triple tone, and multi-tone tests available in REW's signal generator are included. There's both annotated versions with instructions and notes and streamlined versions that take up less space on an LTspice schematic.

I'd originally intended to include a more wordy notes file, but I realized that much of it had been said before by others and it wouldn't be of much interest anyway. So, you all are saved from that.

Thanks, HD Template is a great generator. I understand I can add that to any schematic and have a clean harmonics/FFT run. [Just pondering, would a subcircuit with this be handy, easy to insert??]
But . . indeed some reference as to what the use of all these is for would be fine.

 

[CG]

These "templates" were just meant as a short cut for people (like me!) who want to simulate circuits in LTspice for different types of distortion tests. I took the time to determine what the appropriate parameters for the .TRAN measurements should be for each to get realistic and accurate results.

The simulations are pretty much based around what you could measure in an actual circuit using REW software. This allows for an easier theoretical versus actual comparison of results.

You probably could make these into sub-circuits, but I didn't see the point. For me, anyway. I'm kind of a copy and paste sort of guy. But, if that's what you'd prefer, I'd say give it a try.

 

[jackinnj]

I have several 2SK1020 in my bin. I can't find a Spice model. As an equivalent, the IRF460 is named.
Does anyone have an idea how to get a model?

QSPICE has a model generator for JFET, MOS and DIODES. It takes a little work to get used to it. Probably most helpful in getting the capacitance and diode parameters. Mike Engelhardt is the author and on the DIYAUDIO forum from time to time.

 

[triode_al]

Thanks, I have LTSpice and that working on my Mac. And the Qorvo version, better, is less good on the Apple. Too bad.

 

[KT315A]

older version of LTspice just uses AC sources and does not recognize the fra symbol. I'm not sure what advantages it provides?

FRA is closer to reality because it injects some non-infinitesimal signals. AC is pure idealisation.
However, FRA is way much slower than AC+Tian.
If you arrange several AC tests with different DC-working points then AC will show you a better picture of what's going on in a model.

 

[Mooly]

Would anyone have any ideas on this file that suddenly does not run on latest builds of LT.

The file was posted on diyAudio years ago (I can't remember who by) and its really useful in generating a square wave starting from the zero point, however...

I've tried the file on an older version (24.0.12) and its fine but it will not run on latest build/s. It generates a message I don't understand.

The file is attached.

Edit... just looking back and I see @Ray Waters post here:
https://www.diyaudio.com/community/...from-beginner-to-advanced.260627/post-7952101

I'm guessing this is why its now broken.

After LT update (and I've tried this exact same file on two different systems and both give the error)

 

[Ray Waters]

I've pretty much given up on the 24.1.x branch. The 24.0.12 version works OK for the most part although it too has its quirks. I also keep the ancient LTspice IV version for those cases where even the 24.0.12 version fails. LTspice IV installs as a separate application so it does not interfere with the new version. In my experience, LTspice IV rarely misbehaves.

 

[Mooly]

Thanks very much for the insight on this Ray.

 

[Mooly]

Well unbelievably I think I've fixed it (the file, not LT 😉)

Change the original .par to .param and voila, it works. Was .par ever a recognised command in XVIV I wonder. How weird.

 

[Ray Waters]

Although not documented, LTspice IV does indeed accept either .param or .par as a parameter directive. Similarly, LTspice IV accepts three different directives for specifying options: .opt, .option, and .options all work. The new version parser is much more strict than the older version for reasons that aren't always clear. I don't see any ambiguity among the different forms and it doesn't seem worth breaking old simulations for the sake of "correctness." But that seems to be the mindset of the LTspice developers based on comments they have made on the Groups.io forum.