LTspice newbie - Page 1
Forum section: electronics / beginners

author: duodiode62
author_rank: Contributor
timestamp: January 31, 2021, 05:11:14 am
content: Hello. I wonder if anybody can help me. I want to simulate a very simple circuit to confirm my calculations using LTspice but I just can't get it to work. When I simulate it, I get a table of results, but I can't get any trace to come up. All the example videos show the user simply clicking on a node in the circuit and the trace is shown, however, when I do this, nothing happens. Presumably, the cursor has to be put into some sort of probe mode, but I can't find any command to do this. I used to use PSpice about 25 years ago, but have completely forgotten how to use it, and am a newbie at LTspice.Cheers, Stuart

author: Shannon
author_rank: Frequent Contributor
timestamp: January 31, 2021, 05:15:02 am
content: Post your detailed issue by pictures, that will help us to understand your requirements.

author: duodiode62
author_rank: Contributor
timestamp: January 31, 2021, 09:12:46 am
content: Here's a screen shot. Clicking on the circuit after running the simulation does nothing.

author: iMo
author_rank: Super Contributor
timestamp: January 31, 2021, 09:42:28 am
content: You have set 1 point only for the ac analysis.Also do set AC=1 for the ac analysis otherwise the dB scale should be adjusted..

author: hugo
author_rank: Regular Contributor
timestamp: January 31, 2021, 03:55:40 pm
content: QuoteThis is one of the best LTspice tutorials I've come across:http://www.simonbramble.co.uk/lt_spice/ltspice_lt_spice.htm

author: Terry Bites
author_rank: Super Contributor
timestamp: January 31, 2021, 04:26:44 pm
content: Use Microcap 12 its better its free and it wont drive you mad!its not too late to escape the evils of LTpsice...

author: Ian.M
author_rank: Super Contributor
timestamp: January 31, 2021, 04:53:48 pm
content: If you want to spend time learning to use unsupported abandonware, feel free.Quote from: Spectrum Software WebsiteIts now nearly 21 months since Spectrum Software ceased trading#. How long the 'lights will stay on' for their website is anyone's guess, but the domain expires in 2023.Meanwhile the experienced users on most electronics forums continue to use LTspice for sharing circuit ideas, even if they have better simulation tools available, because its free*so anyone can use it, and supported with ongoing updates, and its essential file formats for sharing sims are ASCII text.* Free as in beer, provided you aren't a potential competitor to Analog Devices.# When the owner of Spectrum Software retired, I do think they deserve a lot of credit for 'doing the right thing' by their user base by disabling licencing so that no existing user would be locked out and all could upgrade to the final version. It would have been nice to see it open-sourced so others could continue development, but its likely that it contains proprietary modules with licences that preclude that.

author: iMo
author_rank: Super Contributor
timestamp: January 31, 2021, 05:06:39 pm
content: Quote from: Ian.M on January 31, 2021, 04:53:48 pmEvery member of eevblog is a potential competitor to ADI

author: Ian.M
author_rank: Super Contributor
timestamp: January 31, 2021, 05:37:56 pm
content: Quote from: imo on January 31, 2021, 05:06:39 pmROTFLMAOPMPEven if you include all the users here who may in the future join the staff of, or even found a competing semiconductor manufacturer, but currently have ZERO potential to compete with ADI without changing occupation, there will always be an irredeemable percentage of non-competitors - i.e. those who's electronic design skills can be summed up as "Can't pour p!ss out of a boot with instructions on the sole", even after Q & A threads on their 'hot'topics repeated ad nauseam. Out of respect for our moderators, I *WON'T* name names . . .

author: duodiode62
author_rank: Contributor
timestamp: February 01, 2021, 11:14:08 pm
content: Thanks for all your replies. I'm going to give Microcap 12 a go.Cheers.

author: gnuarm
author_rank: Super Contributor
timestamp: February 02, 2021, 03:02:20 am
content: Quote from: Terry Bites on January 31, 2021, 04:26:44 pmIt is too late. One use and your brain is infected with a retrovirus and you are doomed. In many ways LTspice is a flaming bag of dog doo. It's just better than many of the alternatives.Seriously though, trying to learn all the rules for using external models drives me nuts... not that it's a long trip.

author: golden_labels
author_rank: Super Contributor
timestamp: February 02, 2021, 05:55:35 am
content: Note: after writing that post I have noticed thatMicroCapis itselfSPICE-ish. That makes the comment below a bit irrelavant WRT that particular program. I do leave it, however, as it is true in general.Sticking to tools commonly used in the industry has advantages on its own. Often outweighting imperfections of the tools in question.Yes, theSPICEfamily of tools will require you to learn a bit and it may be cumbersome at times. But if you post aSPICE-ish model with a question,everyoneknows how to deal with it and is able to help. No one is forced to install some unknown software too.LTSpiceis also well tested and, while by itself proprietary and not easily auditable, its results have been compared to verifiable tools across the years. You can’t say the same about a niche program. I am not sayingMicroCapis bad, as I can’t make any claims of that kind, but as a former softdev I can tell much about sausage making of my own industry. Everyone, even a novice, can make a professionally looking software thatseemsto be working; making a program that actually works and avoids subtle calculation errors requires an expert and years of testing.

author: Ian.M
author_rank: Super Contributor
timestamp: February 02, 2021, 06:28:59 am
content: Microcap's *had* years of testing. What it doesn't have is anyone to fix any new bugs that are found. How many years till it can no longer be run on the current version of Windows? It also hasn't had a major semiconductor manufacturer using it as their in-house SPICE package, (Linear Technology practiced 'dogfooding').

author: golden_labels
author_rank: Super Contributor
timestamp: February 02, 2021, 11:52:11 am
content: Ian.M: they haven’t advertised it well enough on their page —MicroCapindeed isSPICE-ish too. They could’ve writen that in more than one place, paragraphs deep into the product description. I have updated my post above to make that clear. That may change the situation a bit.But,in general, just because a product is old doesn’t mean it got proper testing. A niche program first released even 20 years ago remains mostly untested, compared to even a 5yo piece of software that “everyone uses”.