Author Topic: Simulator for electronic engineering (Read 9016 times)

nickn4 · « **on:** June 09, 2015, 01:07:04 pm »

Good day everyone,

i was watching some of Dave's videos about building your own power supply, and he mentioned to try and simulate one of his schematics.
Soo, i know there are a lot of programs out there to do that, but i would like to know what simulator (software) is recommended (aside from real life try's

) for electrical engineering.

I don't care about costs, just want the most useful application

Edit: changed title from "electrical-" to "electronic-" engineering.

thanks for your time,

nick

Ian.M · « **Reply #1 on:** June 09, 2015, 01:37:37 pm »

A distinction should be made between electrical engineering amd electronic engineering. There's a considerable difference between simulating electromechanical systems (e.g. 3 phase motors, DC traction motors, motor-generator sets), simulating analog and mixed signal electronics and simulating MCUs + digital peripherals.

If you are simulating heavy electrical machinery, you'll be using mathematical modelling. Analog electronics needs a SPICE package. MCUs + digital logic is usually handled by a proprietary simulator, some of which can do SPICE modelling as well (e.g. Proteus).

Linear Technology LTspice IV is a very good free SPICE simulator. Its schematic editor is not the friendliest but once you've learnt to drive it is effective and reliable. It's part library is strongly biassed towards LT's product range but the very active Yahoo group has models for many 3rd party parts ranging from the common to the extremely exotic.

nickn4 · « **Reply #2 on:** June 09, 2015, 01:57:42 pm »

Quote

A distinction should be made between electrical engineering amd electronic engineering

okay that makes sense, i am from the Netherlands and the translation of my part, might be why this misunderstanding happened

The program that i need is just for Analog stuff, electronic engineering, both linear and nonlinear components.
digital components and several IC's are welcome if its implemented but its not a requirement. high power electrical stuff is not a requirement also.
I rather have multiple specialized programs (compatible if possible) than have one program that is good at one thing but lacks at different tasks.

I will try Linear Technology LTspice IV, will let you know what i think about it.

nick

Marco · « **Reply #3 on:** June 09, 2015, 02:16:34 pm »

Simetrix ... unless you like bashing your head against convergence problems.

inteljoe · « **Reply #4 on:** June 09, 2015, 10:31:30 pm »

I have not used it in awhile, but Multi-Sim was always fun to play with.

http://www.ni.com/multisim/
http://www.mouser.com/multisimblue/

The Mouser version is free. I think the NI version has a trail. I don't remember.

TerminalJack505 · « **Reply #5 on:** June 10, 2015, 12:26:59 am »

I like the Tina simulator.

TI has a free version called Tina-TI. Tina-TI doesn't have all of the features or models that the paid-for version has but it is still pretty usable for analog simulation. You can't really do digital or mixed-mode simulation with Tina-TI, however.

dentaku · « **Reply #6 on:** June 10, 2015, 01:06:33 am »

Circuit Wizard is a surprisingly good simulator considering it's cheesy name and child-like interface.
If it had more parts to choose from I'd use it for almost everything. http://www.new-wave-concepts.com/ed/circuit.html

Dago · « **Reply #7 on:** June 10, 2015, 05:27:12 am »

LTspice seems to be the de facto standard for simulators. It is also totally free.

Shock · « **Reply #8 on:** June 10, 2015, 05:48:59 am »

Paul Falstad has a circuit simulator which has "real time" oscilloscope views and runs in a browser, It does not have any layout or manufacturing features or a large database of components, but for testing quick circuits and concepts though it's great, as well as ideal for beginners.
http://www.falstad.com/circuit/

John Coloccia · « **Reply #9 on:** June 10, 2015, 10:06:02 am »

Another vote for Tina-TI. Excellent program! LT Spice is very clunky in comparison.

f5r5e5d · « **Reply #10 on:** June 10, 2015, 11:48:40 am »

IMO you have that backwards Tina is the ugly one, LTspice is elegant in its focus on real engineer's needs in a Spice simulator

Linear uses LTspice internally - the "dogfooding" makes it the much better product - it isn't a dumbed down demo product

John Coloccia · « **Reply #11 on:** June 10, 2015, 12:21:01 pm »

Oh give me a break. LTSpice doesn't even have basic constructs like pots, whereas you have pots and switches in Tina you can tweak in real-time, along with things like real time scopes. Unless you're doing some large, complicated design (in which case you should just buy a product if you feel you need one), Tina absolutely clobbers LTSpice for the vast majority of what beginners in the beginner's forum are going to be doing, and may clobber it elsewhere in the paid version too.

Whatever...they're both free so you can try them both. I use them both myself, but LTSpice will frustrate beginners that just want a virtual breadboard to figure out how components work, and to build simple circuits. I find myself using TINA the vast majority of the time, not for entire circuits, but for small parts of circuits that I want to sanity check...filters, for example. It's brilliant for that, especially if you need Pots. LTSpice is a nightmare for modelling pots.

John Coloccia · « **Reply #12 on:** June 10, 2015, 02:36:20 pm »

I just re-read what I wrote. It comes off a lot more abrasive than I intend! Imagine it peppered with a lot more smileys...LOL. Seriously, they are both fine programs.

Ian.M · « **Reply #13 on:** June 10, 2015, 04:19:08 pm »

While the facility to twiddle pots and flip switches as it runs is undoubtedly handy for a beginner, serious designers want repeatability,so set up LTspice to sweep the parameter in question (or make it voltage controlled and use an arbitrary waveform generator to program it). Its the only way to go if you want to be able to analytically compare the results from before and after a change to the circuit.

Another older simulator that was quite novice friendly was "Circuit Maker 6" Student Edition by MicroCode Engineering Inc. It dates back to 1998, so may not run well on newer Windows versions but if you are stuck with an older PC it can be useful. It can be found fairly easily on the web at a reputable (.edu) site, however you are supposed to be a bonafide student. MicroCode Engineering, Inc were bought out by Protel in 1998 and Protel became Altium, who have subsequently reused the product name for their totally different web based community PCB layout package.

nickn4 · « **Reply #14 on:** June 10, 2015, 06:49:00 pm »

In my first year of my education, we got a lot of programs introduced to us. All of those were at least 5+ years outdated and not compatible with newer windows versions.
For me that has been an good example to what i might encounter in my future and thus i decided to step over that problem and just get over with it and get used to the bad interfaces and hard to learn programs (because of bad design etc..).
Now i can easily try programs with bad or good interfaces, bad databases, etc and still see the raw potential that i can pull out of the app. I will try to test all programs mentioned and give some feedback on them, in that way future members can use this post of me aswell

nick

rs20 · « **Reply #15 on:** June 11, 2015, 01:47:53 am »

+1 to LTSpice. Interface is unique but really nice to use once you've adjusted to it. As for these "convergence problems"; I find they tend to occur when you have a bad, unstable design. So yeah, I never see the convergence errors

[ To clarify my bad attempt at humour, I indeed hardly ever see convergence errors, but that's presumably because of the types of circuits I design (switching regulators, basic audio stuff) ]

A pot is just two resistors, and LTSpice supports resistors

rbola35618 · « **Reply #16 on:** June 12, 2015, 01:43:30 am »

I like to use Topspice from Penzar Developments. It has a huge library of parts (28000) and it is easy to use vendor spice models. It also convergense very well where I have seen other simulators crash. It is not free and cost about 800 dollars. If you are a professional engineer, it is worth buying it. The company provides fast technical help and can even help with modeling components if you ask them. I highly recommend Topspice.

Robert

nickn4 · « **Reply #17 on:** June 12, 2015, 04:06:44 am »

still in the middle of trying all other programs out, im having difficulties with the basics of spice i geus. no worries though, ill get through it

i am currently Downloading topspice 8.46. its pretty easy to "buy"

will let you know you guys know results.

nick

John Coloccia · « **Reply #18 on:** July 14, 2015, 01:50:49 am »

FWIW, I'm starting to warm up to LTSpice more. I'm really torn between LTSpice and Tina because they both have such strong points, and also some real weaknesses. I think I'm firmly in the "use both" camp at the moment.

uChip · « **Reply #19 on:** July 14, 2015, 03:43:04 am »

A related question: How good are these simulators? I'm not trying to start a flame war. This question is less about simulator to simulator comparison and more about simulator to reality comparison. Or more functionally, how much and for what should I expect to rely upon the simulator?

For instance: I have yet another power supply circuit where an op amp oscillates quite nicely in simulation, presumably because of feedback phase. The actual circuit oscillates as well. So far so good. Simulation and reality match. If I add compensation to the simulated circuit so that there is no oscillation can I expect that making those exact changes to the real circuit will fix it? Or do I just have to try it and see? (Then what's the point of simulation?) How much can the simulation be relied upon to match reality? Are there rules of thumb for when the simulation is not to be trusted?

Just enough to be dangerous: I've been reading The Art of Electronics (v3). Do the simulators like Tina and LTSpice use Ebers-Moll to simulate BJTs or do they use something else?

Thanks,
- Chip

rs20 · « **Reply #20 on:** July 14, 2015, 04:23:52 am »

Regarding BJTs, google it: "The [LTSpice] bipolar junction transistor model is an adaptation of the integral charge control model of Gummel and Poon. This modified Gummel-Poon model extends the original model to include several effects at high bias levels, quasi-saturation, and substrate conductivity. The model automatically simplifies to the Ebers-Moll model when certain parameters are not specified."

So, Ebers-Moll is the worst it can do

.

One disparity between simulation and reality is obvious: in simulation, all wires are perfect zero-length superconductors, and parasitic capacitance does not exist. Reality is... more complex than that. A inherently stable, well-designed circuit will tend to be stable both in simulation and reality; a very unstable, poorly-designed circuit will tend to be unstable in both simulation and reality. Where it gets tricky is when your design is right on the very bleeding edge of stability -- reality and simulation will be very sensitive to initial conditions, and thus they might "disagree" from a casual observer's perspective. With simulation, you can easily do Monte Carlo analysis to try a whole bunch of component values (e.g. resistor/capacitor values +/- 10%) to check that your design is robust. None of this really answers your question, but should give a flavour of what to expect. I mean, sometimes if you build "exactly the same circuit" twice in reality, one will oscillate like crazy and the other will be fine -- what is the simulation supposed to do to tell you this?

Another reason that simulation can be unfairly disliked is that whenever a simulation disagrees with intuition, people tend to blame the simulation. For example, in one of Dave's videos he made a circuit involving a (nominally little, low-power, low gate threshold) MOSFET and in the LTSpice simulation the MOSFET never turned on. Much hate was thrown at the simulation, but the thing is the specific transistor model was randomly chosen from a list, and a check of the relevant datasheet showed that far from a little SOT-23 thing, it was a monster power MOSFET intended to be driven with 12V gate drive. The simulation was absolutely perfectly correct, and yet was labelled as being completely wrong. So for reasons like these, I'm suspicious of people who label simulations as bad; I'll be the first to agree that they require a pedantic level of care to prevent such errors (I mean, in real life, you'd take a moment to check the gate threshold if you pulled a huge MOSFET out of your parts bin). But at the same time, reality is very complex, and no-one's claiming that a simulation will correctly simulate an oscillation arising from the lack of supply decoupling caps (since you have perfect zero-length superconductors connected to your perfect voltage source, decoupling caps just don't make sense in a simulation).

Anyway, far from a yes/no answer, but I hope that's helpful

pickle9000 · « **Reply #21 on:** July 14, 2015, 05:00:50 am »

This would make a good episode on the blog.

uChip · « **Reply #22 on:** July 14, 2015, 10:32:45 pm »

Thanks for taking the time to reply. What you say makes sense. I was hoping for a bit more specifics, but I realize that may not be possible.

I think I will experiment a little. I will try a few circuits from AoE and see if I get the textbook response. I will report back if I find anything interesting.
Thanks again,
Chip

leblanc · « **Reply #23 on:** July 21, 2015, 12:06:03 am »

LTSpice and multisim are popular, so they're worth checking out.

I've use simetrix before, and I have to say that it's easier to get started than LTSpice.

The problem with LTSpice is how difficult it is to import models from other manufacturers (by default it mostly has LT parts). Simetrix makes it really easy. If you just want to build circuits with generic parts, ltspice is fine.

The other problem I have found with using simulators other than pspice, LTspice, and multisim is that manufacturers only provide encrypted models for their complex parts (to protect IP), and can only be interpreted by the simulator they were specifically encrypted for. For example, if you wanted to have a model of one of infineon's smart high side switch for use in Simetrix, well you can just forget about it...

If I was rich I'd buy the complete Sabre package.


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Author Topic: Simulator for electronic engineering (Read 9016 times)

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