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Free electronics simulation software

Discussion in 'CAD' started by Carl, Apr 19, 2007.

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  1. Carl

    Carl Guest

    There is a free electronics circuit simulator available called
    CircuitLogix. Check it out. It is quite amazing. The website for
    the free electronics simulation software is


  2. Hello Carl,

    You forgot to mention that it is only licensed for students
    or have I wrongly understood their license agreement?

    Best regards,
  3. Carl

    Carl Guest

    Hi Helmut,

    As I understand it, they are taking a very liberal approach to the
    term "student". If you are using it at home or in the office for your
    own purposes (ie self-study) it is no problem to download it.


  4. Hello Carl,
    the text below is the original text from their webpage.
    It's very restrictive. They not only insist on on beeing a student,
    they also want the name of your teacher.
    I wonder what you have read there.
    Maybe my English is too bad to understand that. :)

    Best regards,

    The student version of CircuitLogix electronics lab simulation is available
    free of charge to any student studying electronics through an educational
    institution. This edition of CircuitLogix was created especially to provide
    students with free access to one of the best resources available for
    learning electronics.
  5. Joel Kolstad

    Joel Kolstad Guest

    They also specifically disallow schools to deploy it, e.g., network wide!

    With their current restrictions, I can't see anyone who *knows* about, e.g.,
    LTSpice, actually using their product.
  6. Carl

    Carl Guest

    Hi Joel,

    LTSpice is pretty good for analog simulation, but CircuitLogix
    provides both analog and digital simulation.

  7. : LTSpice is pretty good for analog simulation, but CircuitLogix
    : provides both analog and digital simulation.

    Boy! It looks like a "pile on Carl" thread! Somewhat deserved, too,
    since he's obviously a shill for CircuitL*gix.

    LTSpice does some digital simulation also, much more than normal
    SPICE. I'll let the champions of LTSpice elaborate on this point.

    My question about CircuitL*gix is: what type of digitial simulation?
    Can it read Verilog or VHDL netlists and do so-simulation with SPICE
    netlists? Or does it just have a few "digial" circuit elements
    ("and", "or", "not", a DFF, and a counter or two)? If it's the
    latter, then it does about the same thing as LTSpice (or less).
    Nothing to get excited about.

    If it's the former (i.e. Verilog/VHDL), then is that available in the
    freebie student edition?

    And what about handling Verilog-AMS? There are so many free SPICE
    simulators out there nowadays (both open and closed source) that
    CircuitL*gix seems like a "me too" product about 5 years late to the
    party unless it can handle Verilog-AMS, or do something similarly

  8. Carl

    Carl Guest

    Hi guys,

    Well, I give up. Accusing me of being a shill for CircuitLogix is too
    much. To answer your question, Stuart, yes it does do co-simulation
    with SPICE and it can read VHDL.


    p.s. I am a design engineer with Motorola and I also work as an
    adjunct professor at Texas A&M. I could care less about whether you
    download a free version of CircuitLogix, I was more interested in
    sharing some good news about free simulation. Obviously, I shouldn't
    have bothered.
  9. : Well, I give up. Accusing me of being a shill for CircuitLogix is too
    : much.

    Well, no offense intended. Sorry!

    : p.s. I am a design engineer with Motorola and I also work as an
    : adjunct professor at Texas A&M.

    Bully for you!

    : I could care less about whether you
    : download a free version of CircuitLogix, I was more interested in
    : sharing some good news about free simulation. Obviously, I shouldn't
    : have bothered.

    We are leery of folks posting "look at this great new free
    tool" messages here since free tools from commerical vendors usually
    have strings attached [1]. The classic examples are ExpressPCB, which
    offers free design/layout software, but locks you into a proprietary
    output file format usable only at ExpressPCB; and Eagle, whose free
    version is wildly popular with students, but is essentially crippled
    since it limits you to two layers and a fairly small board area. Once
    you bump up against the limits of the freebie Eagle, you've got to pay
    for the full-up version [2].

    FWIW, there are lots of freebie and open-source simulators of various
    flavors out there, including:

    LTSpice -- closed source SPICE with integrated schematic capture.
    Totally rocks!

    ngspice -- open source SPICE 3f5. Still uses a CLI, and not as
    optimized as LTSpice, but it works.

    GnuCap -- Analog simulator with internal engine a generation or two
    ahead of regular SPICE. Open source.
    Can do event-driven simulation as
    well as continuous time. Still uses CLI, and can read
    SPICE netlists (with some caveats).

    QUCS -- A spiffy new GUI-based simulation environment which claims
    to do all kinds of simulation. Open source.
    Incorporates schematic
    capture front end. I believe they have some work to do
    until it's complete.

    Icarus Verilog --
    Excellent Verilog open-source simulator run from the
    command line. Used with GTKWave for waveform viewing, it's
    a powerful tool for Verilog design.

    Alliance VHDL --
    French university project providing a chip design tool
    suite. Includes VHDL simulator. I've never used it so
    I know very little about it.

    TkGate -- GUI based logic simulator. More of an eductional tool than
    a professional design tool, but it's cool nonetheless.

    PSpice -- Years ago PSpice 6.x from MicroSim was downloadable off the
    web for free. Is it still around?

    Tina -- TI's simulation program. Version 7 is a free download. Is
    it some kind of "me too" response to LTSpice? I haven't
    used it.

    Besides these, there's also MyHDL, PyHDL, FreeHDL, regular Spice3f5,
    and plenty of other free simulators out there available on the
    web. And don't get me started on schematic capture, layout tools,
    or chip design editors!

    You can follow the open-source EDA tool space here:

    As you can see, CircuitL*gix is just another entrant into a very
    crowded market space. Maybe it's got some better features than some
    other tool? But from your initial postings it didn't make it seem
    so. Also, commercial giveaways are always to be regarded with
    suspicion. And we're a very cynical group in any event.



    [1] LTSpice being a notable exception, probably because they make
    their money from chips, not from software.

    [2] Nothing wrong with that, since the freebie tool is a loss leader.
    But anybody using it should think twice about the long-term dangers of
    vendor lock-in before they have too many designs done in such a tool.
    Same for CircuitL*gix, I would imagine.
  10. JeffM

    JeffM Guest

    One assumes Carl meant **could NOT care less**.
    Yup. Astroturfing abounds.
    Yup: Lock-in-ware
    True--but, in the year 2007, you have glossed over the biggie:
    Cadsoft's DRM (Lock-OUT-ware)
    --and their recently-implemented treat-'em-all-like-thieves attitude
    (even for fully-paid customers): 8-(

    **The Downside of EAGLE** by Markus Zingg*-*-*-projects-could-no-longer-be-opened
  11. Joel Kolstad

    Joel Kolstad Guest

    Unless they have very specific needs, I'd suggest it's not really in the best
    interest of your students to steer them towards CircuitLogix rather than
    LTSpice. A reasonably sophisticated sernior project could readily exceed the
    circuit size limits of the free version of CircuitLogix. Additionally,
    LTSpice is *very* well supported -- for free! -- on the Yahoo! groups; the
    program's author still posts regularly. Just looking at the web site itself,
    it's clear that they want to *sell students* the "full educational version."
    Of course, there's nothing wrong with trying to make a buck, it's just again
    that CircuitLogix doesn't appear to offer $249 worth of "added value" over all
    the freeware solutions out there.
  12. Joel Kolstad

    Joel Kolstad Guest

    TINA is commerical SPICE package (out of Budapest!) that TI licensed from
    DesignSoft. TI's response to LTSpice has primarily been to provide a
    fuller-featured version of TINA (for free) than they previously had.
  13. Guest

    Hey Carl,

    Thanks for forwarding the link regarding CircuitLogix. I did the
    download and it looks very cool. I couldn't find any info about PCB
    exporting. Do you know if it has that capability?

  14. Kevin

    Kevin Guest

    Hey Carl,

    Thanks for the link regarding Circuitlogix. I did the download for
    the free simulator but couldn't find any information about PCB
    export. Do you know if it has this feature?

  15. JerryG

    JerryG Guest


    I downloaded CircuitLogix last night and there is a VHDL function as well as
    PCB export. Look in the Help file and select "PCB export". I have Multisim
    8 (which I paid $600 for and it is garbage). Someone was mentioning LTSpice
    was better than CircuitLogix, which is quite hilarious. LTSpice looks like
    it was designed by high school kids. I guess LTSpice is ok if you are
    designing really simple circuits or if you don't know much about electronics.
    CIrcuitLogix is the real deal. How they are making money from it is a
    mystery, since they give it away for free. But I don't care. Free is good.

  16. JerryG

    JerryG Guest

    Eagle, LTSpice, and TINA? What is this......Losers anonymous? Those are the
    three worst simulators that have ever been built. At least LTSpice has the
    excuse that they are not really a simulation product since they sell hardware.
    But LTSpice and TINA? Give me a break. Why even post messages when you have
    no clue about simulation software. Stay in school for a few more years and
    then get a job and then post messages. Until then you are just taking up
    valuable space.


  17. Ian Bell

    Ian Bell Guest

    JerryG wrote:

    Because they sell it for $249 Jerry.

  18. Chuck Harris

    Chuck Harris Guest

    In one simple sentence, you have successfully proven that you know nothing
    about simulators.


    LTSpice is a slight variation on the spice used by the chip designers at
    Linear Technology... one of the most highly regarded linear IC manufacturers
    in the world.
  19. JerryG

    JerryG Guest

    I downloaded the software and my wallet still has the same amount of money as
    before I did the download, so I don't see how it cost me $249.

    I understand that there is a full version for $249 with even more bells and
    whistles, but what I downloaded for free from the CircuitLogix site is better
    than what I paid Multisim hundreds of dollars for last year. The free
    download is great. Don't be a party-pooper, Ian. The best things in life
    are free.

  20. Kevin

    Kevin Guest

    That's nice. How's your job at Linear Technologies going. Did they give you
    a raise for your posting?

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