Circuit simulation software - Page 1
Forum section: electronics / beginners

author: HobGoblyn
author_rank: Unknown
timestamp: March 28, 2020, 06:36:47 pm
content: As a total beginner, I'm happy making breadboard circuits at the moment.Over the course of me scouring the internet for advice, I see mentions of things like LT Spice or circuit labs.Are these of any use to someone learning, or should I leave well alone for now? (I'm thinking along the lines of trying things that are obviously going to blow up, things I wouldn't try in real life as I don't want to ruin my components)If they might be of use, the how long is a piece of string questions, which do you recommend? Don't mind paying if it's reasonable (a reasonable one off charge that never expires, I don't do subscriptions for software) .Many thanks

author: ataradov
author_rank: Super Contributor
timestamp: March 28, 2020, 06:44:12 pm
content: Simulators like this are usually not a good way to simulate extreme conditions. Things like LTSpice require a knowledge of how to interpret the results. Depending on simulation settings your results may be different, and you need to know how to distinguish things like oscillation of the circuit vs oscillations due to incorrect simulation parameters. And this is much harder if you don't have intuitive feel for how the circuit should perform in real life.There is no way to simulate "blowing up", of course. You may get some extreme values of voltages and currents, but that's no super exciting.

author: magic
author_rank: Super Contributor
timestamp: March 28, 2020, 07:11:01 pm
content: It's hard to tell without knowing what are the things you would like to try, but there is little harm in trying unless you actually build something based on successful simulation and it blows up.It's a substitute for manual calculations but not for understanding. If you get some result, you should review it and ask if it makes sense and try to understand why things behave the way they do instead of blindly trusting a single number or waveform spat out by the simulator. A great advantage of simulation is the ability to inspect every part of the circuit at any moment in time and get a very comprehensive picture of what happens (or what the simulator thinks would happen, anyway). Spice has quite sophisticated plotting capabilities.Something to watch out for, besides aforementioned numeric artifacts, is parasitics. Things like resistance of cables, stray capacitance between components - if they aren't included on your schematic, they will not be simulated.LTspice is free download. LT gave it away loaded with models of their products to encourage the use of those products.

author: rstofer
author_rank: Super Contributor
timestamp: March 28, 2020, 09:48:12 pm
content: LTspice is pretty much the standard in free software and may very well be the most popular simulation software around - at any price.TI's TINA software is also free but I don't have any experience with it.You should definitely grow with LTspice while you are growing with breadboarding. Even if you are just playing with series and parallel resistor combinations, it is worth the time to simulate. Not to check your answers but just to get used to the simulator. There's a bit of a learning curve.

author: Zero999
author_rank: Super Contributor
timestamp: March 30, 2020, 08:15:26 pm
content: For visualising circuits, real-time simulators can be useful, although they're not as accurate as LTSpice. Here's an online simulator app which is fairly easy to use:https://www.falstad.com/circuit/

author: Mr. Scram
author_rank: Super Contributor
timestamp: March 30, 2020, 08:22:51 pm
content: Quote from: Zero999 on March 30, 2020, 08:15:26 pmIt has its limits but it's much more intuitive than LTSpice. I'd love to see a simulator of LTSpice quality but Falstad convenience and real time capabilities.

author: Zero999
author_rank: Super Contributor
timestamp: March 30, 2020, 09:14:34 pm
content: Quote from: Mr. Scram on March 30, 2020, 08:22:51 pmYes that's true. There is a trade off between accuracy and the speed required by real-time simulators. It's not possible to get both.

author: Mr. Scram
author_rank: Super Contributor
timestamp: March 30, 2020, 09:44:03 pm
content: Quote from: Zero999 on March 30, 2020, 09:14:34 pmNeither simulator makes use of the capabilities of modern multi core CPUs or GPUs. It seems that a properly written application that does could do a lot better. We really have unbelievable amounts of power available to us. A modern GPU has 5 times the TFLOPS of the number 1 supercomputer in 1999, the year LTSpice was initially released. While a 1 to 1 comparison is hard to make it illustrates a lot should be possible with fairly mundane hardware.

author: HobGoblyn
author_rank: Unknown
timestamp: March 30, 2020, 09:57:34 pm
content: I’ve downloaded LTSpice and followed a couple of tutorials. Seems simple enough to use for the basic stuff I’m currently doing, although I dare say I’m only scratching at the surface of the software.I think I will stick with this as I grow my knowledge, but the falstad.com looks interesting and I will probably try some using that too.Many thanks