Multisim vs Pspice for TI/LTSpice - Page 1
Forum section: electronics / beginners

author: watchmaker
author_rank: Unknown
timestamp: December 16, 2023, 03:53:04 am
content: I am evaluating which simulation package to learn. Multisim seems to be the most intuitive. But I must not be understanding Pspice for TI. It seems very cumbersome for assigning values to components. I refuse to believe it is that hard to use.Is there a decent tutorial for it? At this stage I am only dealing with passives, but I would like to learn a simulator I can stay with.Regards,Dewey

author: Konkedout
author_rank: Frequent Contributor
timestamp: December 16, 2023, 05:30:07 am
content: I am no simulation expert but with my employer we use LTSpice mostly. LTSpice has the advantage of included ADI/LT models, while TI PSpice has TI models. Either can import models. I think LTSpice is easier. Certainly the list and structure of data files associated with LTSpice ismuchsimpler than that for TI PSpice. Unless I have imported models, very often I can send someone else my LTSpice simulation with the .asc file only, and those file sizes are usually under 20KB or so. The .asc file is also editable with a text editor; that is occasionally useful and I did that today in fact. With TI PSpice you need to zip a much bigger folder if you want to send it to someone, and the folder structure is confusing as heck.With previous employers I have had good experience with Simplis/Simetrix (now offered free "Mindi" by Microchip) and PSIM many years ago.

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: December 16, 2023, 09:27:58 am
content: The one I mostly use is Tina, the student version is around 50 euros. TI have a free version of it, although that is somewhat limited. If you have deep pockets, there are more expensive versions.https://www.tina.com/SJ

author: watchmaker
author_rank: Unknown
timestamp: December 16, 2023, 11:53:10 am
content: Thanks both.I should have stated I do have Multisim, TINA, Spice for TI, and LTSPice. All were free with the exception that Multisim was downloaded from Internet Archive.In use, the Multisim enables value changes pretty easily. Spice for TI and LTSpice seem set up for established libraries of parts, I do not see a way choose values without going thru the parts editor.I DO like the probe on one of them.So far I like Multisim the best, but I do not want my ignorance to determine my choice. I am willing to watch a couple Into Tutorials that demonstrate using each of the others to set up passive networks w/ power sources and analysis. Also labelling nodes. All basic stuff I know. But I need to watch to learn.THANKS!Dewey

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: December 16, 2023, 12:05:54 pm
content: Hi DeweyLTSpice has parts and models for Linear Tech (now Analog Devices) parts, and Tina-TI parts for Texas Instruments designs. Not really a surprise as these programs are free.The paid for version of Tina is not so restricted, you mentioned having a free version, is that for the Texas Instrument one? If so, it has more limitations than the cheap student version I use.Horses for courses, I guess. For my fairly basic use the 50 euro version of Tina does most of what I need, although I did use LTSpice to resolve an issue with an LTC4368 protection board. See this thread for the circuit and model:https://www.eevblog.com/forum/projects/ltc4368-over-current-protection/SJ

author: RoGeorge
author_rank: Super Contributor
timestamp: December 16, 2023, 12:32:40 pm
content: It's kind of hilarious, but sad at the same time, to find out that TI is asking money for the cumbersome TINA-TI, when there are so many alternatives out there. In fact it's hard to find a more cumbersome simulator than TINA-TI, free or not.Components libs and models are compatible between any SPICE-like flavors, maybe with very few exceptions (and even those exceptions can be easily ported with a simple text editor).As for the OP, learn LTspice.LTspice is free for students and for non-commercial, it's the easiest to use, has an intuitive interface, and it's the de-facto industry standard for SPICE-like simulators. Electronic components models for are compatible between LTspice, PSpice, Tina-TI, ngspice, etc, so almost any SPICE library can be used. Another advantage for LTspice is that it has some additional/optional math methods (e.g. '.option method=gear'), which makes other simulators dont have, and which makes LTspice to simulate the circuits faster and more precise/reliable than other SPICE-based simulators.Also, there is large community support on the web, and there are countless tutorials for LTspice, either video or in written format.https://www.analog.com/en/design-center/design-tools-and-calculators/ltspice-simulator.htmlEven if they don't say in their main page, LTspice works in Linux or in FreeBSD, too, if you install WineHQ. I'm using LTspice from Linux.QUCS and QucsStudio are other alternatives to the SPICE family simulators, they are less popular and with a less user friendly interface, but with some RF goodies, RF filters, microwave striplines, Smith charts, etc.

author: watchmaker
author_rank: Unknown
timestamp: December 16, 2023, 10:09:29 pm
content: I spent some time working LTSpice and Pspsice for TI. I found the easy way to change element values. Now I have to get used to the various ways the results of simulations are reported.I see the differences are actually very subtle and that time has to be spent getting each one set to the way the user wants. Not as bad as Photoshop at least.But I paid nothing for all three so I cannot whine.Thanks!Dewey

author: LinuxHata
author_rank: Frequent Contributor
timestamp: December 17, 2023, 12:22:15 pm
content: I had several attempts jumping into simulation, but quickly figured out, that for most circuits I do, it is faster to build actual prototype and test there.All these simulation software, including paid ones, like Proteus, have awful user interface, zero ergonomics and appear to be designed around early computer ages and nothing changed since then - they use zigzag resistors, non-standard keyboard shortcuts, and are very slow. For example, LTSPICE makes no use of multi-core processor support, and quite often, I have to wait for 5-10 minutes for a 10ms simulation to complete, despite that I'm having 6 core fast CPU. I go to device manager and see that LTSPICE hardly hitting 12% of CPU usage.Also I found that in LTISPICE the breakdown voltages and limit voltages in general, are not considered - say, boost IC can output max. 40V, but if you adjust feedback resistors accordingly, in LTSPICE you can have 200V at output, despite having both IC and diode rated at 40V max.I really can't understand, why there are no streamlined GUI, industry-standard control alignment and any other ergonomically correct interface components?

author: RoGeorge
author_rank: Super Contributor
timestamp: December 17, 2023, 01:37:27 pm
content: The single core usage was an issue in LTspice some time ago. Now, mine shows 8 cores (Ubuntu + WineHQ + LTspice). However, during simulation it doesn't hog the proc to 100%, most of the time is spent saving the produced data, or redrawing the plots if it is set to redraw last plots during simulation.The proc usage can go close to 100% if the task is set for a higher priority, though it might not improve much the total time.Casual simulations will finish instant, 3-5 seconds or so. Raw computing power won't help much. When a simulation takes longer than a few seconds, most probably something is not right, usually a sloppy component model, maybe a wrong setting, too smaller time steps, things like that. Other times a long simulation time can be drastically reduced by changing the initial condition, or starting with charged capacitor, etc. Other times, changing the integration model from 'trapezoidal' or 'modified trapezoidal' to 'gear' might help. Sometimes changing gmin or reltol, etc. Can be very frustrating and difficult to fix, indeed.True that SPICE libraries do not model components breakdown, and also true one can easily spend an entire afternoon fiddling with a simulation because modifying a schematic is so easy. Would be a lot faster to just solder the physical circuit.With all these, simulators are an invaluable tool when it comes for learning electronics, or to quick test an idea, or to optimize an existing schematic, or to probe signals that an instrument might not be able to catch, and so on.

author: shapirus
author_rank: Super Contributor
timestamp: December 17, 2023, 01:46:06 pm
content: Quote from: LinuxHata on December 17, 2023, 12:22:15 pmHow would you parallelize an algorithm in which every iteration depends on values calculated in the previous iteration?There are algorithms that cannot be parallelized. I'm no expert in this specific field, but it naturally feels that circuit simulation cannot be split into independent chunks each of which can be processed by its own CPU core.Quote from: RoGeorge on December 17, 2023, 01:37:27 pmRight, but they do simulate voltage and current, and that can be used to estimate whether the operating conditions of the component are within safe limits. Besides, simulations sometimes fail (with obscure messages) which may indicate that something isn't going quite right in the circuit.

author: shapirus
author_rank: Super Contributor
timestamp: December 17, 2023, 01:50:07 pm
content: Btw, multisim, as free as it now is, may be not the best choice simply because it is discontinued.edit: confused with microcap!

author: LinuxHata
author_rank: Frequent Contributor
timestamp: December 17, 2023, 02:21:23 pm
content: The bundled sample circuits of LTSPICE also work quite slow. Try the LT1370, for example.

author: RoGeorge
author_rank: Super Contributor
timestamp: December 17, 2023, 03:05:33 pm
content: 1370.asc took on a 4core/8thread@4.0GHz/32GB RAM about 5-6 seconds with thread priority high (from the LTspice settings), and about 8-9 seconds on priority medium. Not instant, but still usable.There are more settings regarding the threads nice-ness in WineHQ and in Linux, but I didn't try.Forgot to say, LTspice has European symbols in the  category, called 'EuropeanResistor', 'EuropeanCap', 'EuropeanPolcap', etc. Apart from those, new custom symbols can be created any shape and form from Hierarchy -> Create a New Symbol.

author: LinuxHata
author_rank: Frequent Contributor
timestamp: December 17, 2023, 07:43:43 pm
content: Yes but when you alter some parameters "on the fly" and you have to wait each time these 4-5 seconds, still too slow - far more CPU intensive tasks are solved on modern PCs in almost realtime.Also, I don't see any hot key for these "european" resistors at all

author: shapirus
author_rank: Super Contributor
timestamp: December 17, 2023, 08:04:06 pm
content: Quote from: LinuxHata on December 17, 2023, 07:43:43 pmProteus is quite good at this. It simulates pretty well in real time (well, almost, there is some non-1x scale to it) and allows interaction with the circuit while it is being simulated.Its cost is totally insane though (in case it's honestly purchased). Might be fine for companies, but definitely not for individuals.

author: RoGeorge
author_rank: Super Contributor
timestamp: December 17, 2023, 08:25:28 pm
content: Quote from: LinuxHata on December 17, 2023, 07:43:43 pmIf you want the EU resistor as the default symbol for 'R', make a backup copy for the fileLTspiceXVII/lib/sym/res.asythen copyLTspiceXVII/lib/sym/Misc/EuropeanResistor.asyasLTspiceXVII/lib/sym/res.asyor make a symlink or a shortcut instead of copying.As for keyboart shortcuts they are standard, but not the one you want. They can be changed from settings. Pays a lot if you choose single keypress shortcuts (without key alterators) for most common actions. For example I have 'm' for move, 'd' for drag, 'p' for place part menu, etc. Has a set of shortcuts for plots and chart handling and annotations, too.My point is, LTspice in special, and simulators in general, are not to be despised or regarded as useless in practice. Simulators are of a tremendous help, particularly for students and beginners. Not everybody has jellybean parts at hand, and lab instruments, and skills, and time to test an idea in practice.I know that simulated electronics is simulated fun. Nothing can beat the hands on experience, and the satisfaction of physically building something, just that we shouldn't dismiss simulators as not worthy.

author: LinuxHata
author_rank: Frequent Contributor
timestamp: December 18, 2023, 04:55:38 am
content: What I'm trying to explain is that these simulators in terms of ergonomics, user interface, simplicity of use and so on are far behind the current software package levels for other activities, like text and data processing, graphics design, music editing and so on, by at least, 20-30 years.As a reference, have a look atwww.logic.lysoftware (free online demo opens right in browser -https://logic.ly/demo/). Yes it has quite limited set of features but see how simple, fluid and fast simulation is there?In Proteus, you have hard time connecting wires together, here everything is done soo simple...

author: RoGeorge
author_rank: Super Contributor
timestamp: December 18, 2023, 10:46:41 am
content: Indeed, most CAD tools are not particularly friendly, electrical, mechanical or otherwise. They all need to read the manuals and get some training first. They are very specialized tools, so they are not exactly intuitive. They have their own world, but after some practice, such tool can be very productive.As for the logic.ly, yes, that's very eye candy. Though, comparing that with established CAD tools is a little unfair, because for example a program like SPICE has had a history of half a century already, and they kept their backwards compatibility, while a very recent tool like logic.ly has had the freedom to choose whatever appearance, and the freedom to disrespect any industry standards and innovate (e.g. by using Bezier curves for wires, instead of orthogonal lines).Spice doesn't shine at digital simulations. For heavy lifting when it comes to digital, there are other tools, like ModelSim and other HDL simulators. Same as other CAD/EDA tools, can not be used without reading the docs and some practice.For digital simulation, easier to use yet a 100% professional tool, Quartus (the toolchain for Altera FPGA's, now Intel) has a TTL library and an interesting GUI editor, where one can drag and drop TTL chips. Particularly useful for those who already designed with the TTL family, but are not yet comfortable switching to HDL.Quartus has a free version, too, worth a try when it comes to digital design. Even if one eventually doesn't like Quartus, at least the time was spent learning and practicing with an industry standard tool, a tool that won't go away, one that will be encountered later in one's carrier.

author: watchmaker
author_rank: Unknown
timestamp: December 21, 2023, 12:48:44 pm
content: I finally figured out that I was ignoring "modeling application" in TI pSpice (under "Place Pspice Comonent") to create independent voltage sources.I realized in both that you should configure the toolbars (get rid of unneeded toolbars, add buttons for convenience) in any of these to the task at hand.I like the Electrical Rules Check in MultiSim, and the simulation reporting.TI pSpice allows you to move the schematic to a second screen but I need to spend time figuring out how to use Rules Checker. I have not found an option for instruments so I need to learn how to use the "probes".I am not sure which is better for me. That will take time, but it seems the textbooks I am using favor OrCad (TI sPice).But it easier to verify my results for resistor network problems with either than breadboarding, which is now reserved for the lab exercises.Dewey

author: abeyer
author_rank: Frequent Contributor
timestamp: December 21, 2023, 09:57:54 pm
content: Quote from: RoGeorge on December 18, 2023, 10:46:41 amlogic.ly itself is relatively new, as is the webbiness aspect, but that UI is near identical to one I recall using on macos 7 in the 90s, so it has a good ~30 years going, too.The fundamental problem is that there hasn't been (or at least I've never seen) any sustained interest in building any free tools that care both about powerful/accurate/correct simulationandreally polished UI. The really good simulators get the sim right, and then stop there. While the projects that focus on UI never invest in getting great simulation working.

author: shapirus
author_rank: Super Contributor
timestamp: December 21, 2023, 10:02:17 pm
content: Quote from: abeyer on December 21, 2023, 09:57:54 pmThat's why there is some hope in KiCad: the EDA suite and the simulator (ngspice) are basically two separate projects. And both are actively developed. Yeah they do require a good bit of patience and learning, but at the end of the day they are usable.

author: zapta
author_rank: Super Contributor
timestamp: December 28, 2023, 05:14:54 am
content: Quote from: LinuxHata on December 18, 2023, 04:55:38 amYes, they are horrible. Gray Beards and 'full stack' UX hipsters do not mix.

author: tychob
author_rank: Contributor
timestamp: December 29, 2023, 04:33:13 pm
content: Quote from: shapirus on December 17, 2023, 01:46:06 pmBy parallelizing within an iteration, calculating the values for all the nodes in the matrix in parallel. Whilst not perticuarly efficient on CPU cores, this approach does work with GPUs, and there is cuspice which is a fork of ngspice, which can use cuda to accelerate large simulations like this:https://ngspice.sourceforge.io/cuspice.html