What circuit simulator does everyone use.

[Ferroto]

I've been using the demo for ISIS to test out designs, as I'm a broke collage student. I test designs with ISIS, but can't save them because it's a demo. So what I do is
complete my designs in EAGLE, then test anything new out in ISIS. It would be nice if I could save projects, but again it's a demo. My question is. What circuit simulation software
do you guys use? Are there there any free equivalents to this program?

Here's an action shot of what I'm talking about.

[GeekGirl]

My Circuit simulation software is ...... real hardware Nothing beats it, if I am trying to get something new to work, I may breadboard it, but mainly just ecad schematic and PCB, then build prototype, these days with uC / uP / FPGA / CPLD, most hardware mistakes can be fixed in firmware

[djsb]

Hi,
For simulation there's QUCS

http://qucs.sourceforge.net/

and KTECHLAB (mainly for use under linux). This program is unstable at the moment and is being rewritten.

For pcb design there's KICAD

http://kicad.sourceforge.net/wiki/index.php/Main_Page

These are the main one I know about.

David.

[jahonen]

I usually use Linear Technology LTSpice aka SwitcherCAD, great for analog/SMPS simulations. For VHDL, I usually use those free FPGA vendor versions of ModelSim. For low-speed digital design, signal integrity simulations are not usually necessary.

LTSpice is not node or component limited in any way. The only drawback is that there is not very great collection of general purpose parts included, but you can quite easily add just about any SPICE macromodel, once you figure that out how.

Often neglected very useful feature of the simulation is that it can tell you easily things you can't even measure on a real prototype. Or simulate effect of component tolerances using monte carlo simulation, to see if your design is going to work with real-world tolerances. Of course, this is more relevant to analog design.

Regards,
Janne

[Zero999]

I use LTSpice both under Windows and Linux.

I haven't tried any native Linux simulation programs yet.

[migsantiago]

Yes, I also prefer hardware debugging. Proteus ISIS is full of glitches, especially with PIC microcontrollers.

You could break your head trying to figure out why your firmware doesn't work on Proteus and the solution is that Proteus is flawed.

[comox]

Actually, I use LabCenter's Proteus (Isis and Ares)!  I am using a commercial/licensed version, which is presently at version 7.7.  I am not sure as to the release level the "free" version.    I have been using it for about 3 years now and am quite satisfied as it is good value for money.  I have the PIC16 emulation license, and did use the PIC emulation quite a lot during the first year (2007).  I was developing code in C and compiling using HiTech Software PICC16 compiler and had no issues with the PIC emulation.  I was also using the Isis I2C emulation as well with no issues....

However, I no longer use the emulation as I have moved to the PIC18F architecture and do not have a PIC18 emulation license; also, I am now using lots of I2C devices that are not emulated, so it has been easier to run compiled code on the hardware.

I now use Proteus for both scematic capture and printed circuit board design, but I do not use the built in auto-router and instead use the Electra auto-router (which integrates with Ares) as I find it better.  In fact, I just had a batch of boards come back from manufacture yesterday based on CAD/Gerber data generated by Proteus Ares.  They are a work of art, and Ares is fairly easy to use.  

[ArtemisGoldfish]

I've used Proteus ISIS for doing some simulation of microcontroller circuits, but primarily, I use Multisim 11 (I blame my school for forcing me to use it.) Does what I need it to, that's the primary thing.

[rossmoffett]

I have Qucs, there's also another one called Electric VLSI (http://www.staticfreesoft.com/) that has a Java and C code version.  The Java version is free.  I think it's pretty nice, but I haven't done anything advanced with it.

(I've been using Ubuntu for some time, I don't know what the Windows compiles are like)

[jimmc]

Not really in the same league as the others but if you want a very quick and easy RF linear simulator try RFim99.
Freeware from several places eg

http://electroschematics.com/wp-cont.../rf-sim-99.zip
or
http://www.101science.com/RFSim99.exe

(Works on Windows 95 to XP, I don't know about Vista / 7)

Very useful for quick calculations. eg Under tools it has a calculator with 4 boxes

Capacitance
Inductance
Impedance
Frequency

Enter any two and it will calculate the remaining two.

It does much much more including:
Linear simulation from simple schematic input with graphical output
L/C Filter design with the ability to see the effect of 'rounding' component values.

An oldie but goodie

Jim

[free_electron]

Altium Designer. Everything else is a toy. Seriously.
That being said. With this one package you get:

- schematic entry
- mixed mode simulation
- pcd design
- mechanical design
- vhdl / verilog compilers. ANY Fpga. really, ANY. Altera, Xilinx, Lattice , Actel. they are all supported. you can even switch from one vendor to another mid design.
- a truckload of IP blocks like cpu's , i/o.
- all the compilers for those cpu's.
- hardware / software co simulation if you get their jtag probe. if your design has a cpu or FPGA it will show you  in quasi realtime the 1 and 0's on the pins in your pcb layout or schematic view.

Want to have some references as to whom uses this software ? Know those two little thingies that rove mars ? bingo.
Ever heard of companies like SpaceX , Bang & olufsen , National Semiconductor, BSA , Boeing , BMW and many more ? bingo.

Since you are a poor student : Call altium. Provide proof you are a student. They will give you a full blown licence for 100$. Valid for two years i believe.

If you are not a student. Too bad, it'll cost you 4995$ + 1500$ maintenance a year to have a perpetual licence.
If you do not need the PCB but want everything else its 995$ for a perpetual licence.
The maintenance gives you free mayor updates. They release a full version every 6 months. It is NOT mandatory to buy maintenance.

And if you want to go crazy over FPGA design check out their NanoBoard 3000. you get the hardware board + the software ( minus the PCB module) for 395. That software versions is tied to the specific nanoboard you buy and stops working after 1 year.

If you want to play with it for 30 days : go download it from their site and request a demo key. Caution : the download file is large ... 1.7 Gigabyte install file.. IF you want the FPGA support qou will also need to download Xilinx ISE , Altera's quartus or the equivalent tools from Actel or Lattice ( these tools are all free. the only caveat is that each of these installers tags on another 1.5 gigabyte to your download)

For the good order : i am NOT affiliated with Altium. I just have been using it for a long time at work (started when it was a dos program with version 1.1. i still have the 720k floppy it came on. I have my own licence for home use and am a very happy camper with that software. I have used Pcad, Boardstation, Pads , OrCad stuff from Visula, played with Eagle , Isis, Kicad , gEDA, diptrace and some other stuff. Doesn't cut the cheese ...

[Ferroto]

If you are not a student. Too bad, it'll cost you 4995$ + 1500$ maintenance a year to have a perpetual licence.
If you do not need the PCB but want everything else its 995$ for a perpetual licence.
The maintenance gives you free mayor updates. They release a full version every 6 months. It is NOT mandatory to buy maintenance.

Although what I saw with regards to Altium on youtube was quite impressive, it's the single most expensive piece of software I've ever heard of. I mean $4995 is 2000 bucks more then I've ever spent on a single piece of computer gear (software or hardware) in my life, and I'm a Mac user 

[free_electron]

you stated in your original post you are a student. It's only 100$ then.
And as far as software price... 5K is peanuts. Ever looked at a licence for a circuit simulator like Eldo or a synthesizer from Synopsys ?

[Ferroto]

you stated in your original post you are a student. It's only 100$ then.
And as far as software price... 5K is peanuts. Ever looked at a licence for a circuit simulator like Eldo or a synthesizer from Synopsys ?

I'm taking a Networking Administration course. I'm not actually taking an EE course so I don't think I'd qualify for a discount.

[rossmoffett]

Check into it anyway, not all student discounts require you to prove what kind of student you are.