Simulating Design with Actual Components

Discussion in 'Electronics Resources' started by jegues, Aug 3, 2013.

  1. jegues

    Thread Starter Well-Known Member

    Sep 13, 2010
    Evening Gents,

    I'm wondering how I can simulate my circuit design with the models of actual ICs before buying all the components for my project.

    I've looked in LTspice and Multisim and found some components, but I am still missing some of the components I want to use in my project. (For example LM7805)

    Is there a way to import other ICs into either multisim or LTspice? If so, how?

    Is there another more convient way to simulate my circuit so that I don't end up buying all the parts and finding out that it doesn't work as expected?

    Thanks again!
  2. #12


    Nov 30, 2010
    I think I heard of a website where you can present your circuit and people that have done that sort of thing will check it for you. Lemee think...where was that website...
  3. tubeguy

    Well-Known Member

    Nov 3, 2012
  4. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    Eventually you will need to step out and take the risk of not having immediate success. Trusting in simulations is risky business - particularly as the complexity of the design increases.
  5. MrChips


    Oct 2, 2009
    I rarely do simulations. I get real components, connect them together and see real results.
  6. jegues

    Thread Starter Well-Known Member

    Sep 13, 2010
    I can relate, but the cost of various components I'm interested in are quite high hence why I would feel much more comfortable simulating the circuits before shelling out the cash.
  7. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    You could post your design concepts & schematics. Forum experts might point to any obvious deficiencies.
  8. WBahn


    Mar 31, 2012
    Contact the manufacturers of the components and see if they have SPICE models. They may not have exactly the models you need, but they may have ones that are easy to modify to make them compatible with your simulator.

    But be aware that many manufacturer models are not intended to be particularly faithful, particularly when it comes to power supply currents. But they will sometimes focus on getting timing and frequency response behaviors realistic but have very unrealistic input and output current characteristics (the I/Os will tend to be overly idealistic).

    Also, many manufacturers are pretty easy to get sample parts from, even some pretty spendy parts.
  9. Brownout

    Well-Known Member

    Jan 10, 2012
    In a word, yes. You can import netlists of IC's into the library of components. Also, you can import symbols and have them available in the part selection menu. The netlists/symbols can be obtained by either the manufacturer or by PSPICE users groups (check yahoo) You can also make your custom parts and symbols for inclusion in your libraries. It's not hard to make the custom netlists for popular IC's ( take the 555 for example)

    I don't use LTSPICE anymore so I can no longer walk you through the process. Basically what I did was to browse through the directories and find the libraries, then copy my modules into them. There is a simple drawing utility in LTSPICE for making symbols.
  10. Mussawar


    Oct 17, 2011
    Multisim has a large number of components along with their foot prints in the Master Database. It's true that it can't cover all the components. So many of them are not available in the database (i-g 40110B etc.) But most common components are readily available; as you pointed out about LM7805. I remember that it is available in the Master database. Beside this you can use many techniques to manipulate it. For example you can use a 5V DC power source instead of 7805 to simulate your circuit.

    It is also a fact that simulation doesn’t always give the desired results. There are certain limitations while using simulator. For example when you make a 555 monostable without using Pin7, it works fine in real world but would not work in simulator.(You can try it). Personally I use Multisim mainly for drawing the schematic and Ultiboard for PCB design. (Regards)