A free Spice program available : emulate your stompboxes

[zpyder]

This looks reallllly sweet, but I'm totally confused. 

I finally figured out how to make an input and an output (I think... I do a Label Net and select Port Type of Input or Ouput - right?)... I've created a simple hipass filter (though I didn't do the math and the numbers are probably crap), one capacitor and one resistor, a signal path through, and one ground dump...

I tried to run the simulation, entered the stuff into the boxes and got this command:
.noise c:\test_out.wav c:\test.wav lin 100 20 1000

But then when I ran it it told me "Node IN is floating" and that there was less than two connections to Node IN...wtf     Soo.... I added another huge resistor to ground from in to see if it likes that, and now it gives me a different error: ".NOISE syntax error"

So I looked at the syntax and instead used this command:
.noise V(c:\test_out.wav) c:\test.wav lin 100 20 1000

Now it says "Unknown node in .NOISE card: c:\test_out.wav"

wtf is going on here??

I saved my file and it is located at www.mattrabe.com/wtf.asc.  There's also www.mattrabe.com/wtf.log and www.mattrabe.com/wtf.net don't know if they're necessary at all.  Perhaps someone could take a look at it and/or help me out...

thanks a lot,
matt

[GibsonGM]

this software looks really cool! But I can't understand enough French to get a wav in there to try out a simple lowpass filter...maybe someone will post something to help us along? 

[zpyder]

fxdfxd - thank you so much for that tutorial!!  I guess I should read a little more before I ask silly quesitons...
GibsonGM - go to fxdfxd's tutorial.  It is in french, but watch it trust me.  Just do everything along with it during the pauses.  (I don't speak french)

HOWEVER ....... Mine still will not work!      When I click on run, it just says "Initializing circuit matrix..." down in the status bar and nothing ever changes... I noticed that in the demo, it said "Starting SPICE run..." down there... mine never did that.

I hope someone has a clue what I need to do because I'm startin to get some blue balls here... and unfortunately I don't speak french so all I can do with the demo is mimic it........

please help...

[zpyder]

Well, I just walked out of the room, a little frustrated, went and made some pasta salad, came back down and OH MY LORD it worked.  Pretty stoked.  I got some weird error message, but the output file exists!!

THANKS!

Gibson - you should do what I did

[GibsonGM]

LOL, glad it worked for ya, Zpyder!  I spent some time on the net w/a French translator site...came up with the following, hope it helps everyone.   I'm going to try it out tomorrow -- bedtime here.  Forgive my errors in this, I just interpreted it as best I could.  Maybe one of our French-speaking forumites can fill in my missing gaps and mistakes!!!!    Each group of sentences is 1 screen message in the tutorial (I think!):

------------------------------------------

In this demonstration, we will see how to create an audio file to be able to listen to the behavior of an assembly.

One starts by creating a diagram.  For this example, I will make a high-pass filter because there is adze can of components, and the result will be audible.

One presses R for a resistance then one clicks with the mouse to place it on the diagram.

One presses C to have a capacitor then CTRL-R to make a rotation.
One presses G to place the mass (I think this is ground)

One presses F2 to choose of another components here one want a source of tension-the component is 'voltage'
it is here that one finds the FET (njf for a channel N) or the lamps (triode for by ex a 12ax7)

one wires the components while pressing on F3

I will now add a label.  It will be necessary to later specify the place of the diagram which must produce the audio file.  To add a label, to press F4.

It is now necessary to put values on the components. One does it with a click-right on the component.   I will make a filter with a frequency of cutoff (?) towards 1000 Hz.   {eqns. follow which yield the 15 ohm resistance}

attention it is HERE that  {adding the input wave} occurs!!

It is necessary for the mouse to be on the V of our source of tension {voltage}. The mouse must change drawing to post a kind of L. then click-right.

Here one comes to say that our source of tension {voltage} will be based on an audio file wave.  Thus file will be simulated with notes of guitar entering the circuit. SwitcherCad regards a file wave as having a maximum voltage of 1v-1v P to P (I think).  As a signal of guitar is rather about 100mV, one can sometimes use a voltage divider in between for better simulation of our signal of guitar.   Once again this file must already exist on the hard drive ! This is not the file of result, but the signal being input {??}.   For the path, I put c:\oca but you put what you like.

Let us exit the circuit.  To make Switchercad generate an audio file, one must put a directive to him while clicking on ".op"

And unveiling the magic line which will say that one wants a wave file in  ex: C \ oca \ OUTPUT.wav  {where the prog. will write the output wave to}   and that to card-index it this on the signal of the label "out will base".  ATTENTION the max level of output is usually between -1V and sometimes 1V thus if amplifiers are simulated it is necessary to make a voltage divider on the output if not the file will be clipped ((and it is beautiful part of the whole))

Thus this label

It does not remain us any more which simulation has to launch {??}

>the simulation will last 4 seconds.  Chose timestep (I am guessing now)

One can select the trace which one wants to visualize during calculation. That does not have an influence on the audio file generated which will come from any way of the label out

It ran. ...{garbled}... time lasts remains very raisonable for FET, it is longer with other models.

Voila , you are finished.

[Gilles C]

I wish I had more time to get to know it, but it will still have to wait a few days before I can play with it.

Until then, I am reading the thread to make sure it works when I try it...

I hope it works soon for you guys.

Gilles

[fxdfxd]

Hi

Is there's any problem ?
Ok, there are some important point to clarify. These are the most important points to use wav in your sims :

- You must have an voltage source, and right click on the voltage value (called V in the software), then add the following command : WAVEFILE=your_file.wav, set here the path and name of your input file.

- you must have an output label, for example called 'out' ("label net"-> in port type, choose 'output', enter a name)

- Add a SPICE directive, ("op" -> then enter ".wave your_output_file 16 44.1k V(your_output_label)" in the text area

Then just run the sim like you always do

Hope this helps

-fx

[fxdfxd]

This example is available here : http://f.defaut.free.fr/perso/divers/Example.asc

Just save it and open it in PSPICE. Be sure to change the name of the input file to match your's

Tell me if there're still some problems
-fx

[GibsonGM]

Thanks, FX! I probably had a couple of settings wrong. It works great now!  Nice find, better & easier than breadboarding a ckt just to see what it will do to a tone stack.  I'm sure I'll find many uses for this one!

So, you just add the voltage source in place of the guitar, correct?

[zpyder]

GibsonGM -
yes, you add a voltage component, and then set it to your wavefile input.  So if you built a schem of any effect, instead of having an Input jack, you would simply have a voltage component which references your wave file.  And there will be no true "voltage source" as you'd think of it when actually building a circuit.

Anyone -
I've gotten everything to work using the link that Gilles provided at the start of this thread.  That is, I've had it output an altered wave file based on a simple hipass and also a signal canceling circuit (higher resistor to output than ground).  Both worked after a LOooooong time, and the program crashed.  I created a simple booster circuit (which has several more components than either of the ones that worked) and the thing just hangs... Not sure why.  I've seen references to "PSpice" in here, but the link Gilles provided had me download a program called "LTSpice".  Are they the same?  Should I/Can I get "PSpice" also?

thanks!

[Transmogrifox]

what exactly is this? 

This is a computer program that allows you to draw a circuit in schematic form.  A mathematical model of each component (transistor, resistor, capacitor, op amp, jfet, etc...) is programmed essentially into each schematic symbol.  When you run it, it simulates the analog circuit.  That way you can fine tune things and look at frequency plots and bias voltages without having to ever build it on a breadboard. 

If you simulate a stompbox circuit, you can use a .wav file of your guitar to simulate what it may sound like.  This would help you decide if you wanted to build the effect without having to spend money on parts and spend a lot of time building and debugging a real circuit only to find you didn't really like it much anyway.

[zpyder]

Node 2 Floating Error...

I've put a couple of Francisco Pena's (www.tonepad.com) clone schematics into LTSpice and I'm having a recurring problem.  It keeps telling me that Node 002 is "floating".  Node 2 is the first node directly after the Wavefile input (in both of my examples).  I wonder if anyone knows what I'm doing wrong here...

http://www.mattrabe.com/circuits/schems.zip contains two .asc files, one for "El Boosto" - aka EH LPB-1 and one for "Mucho Rojo" - aka Red Ranger.  It also contains a .txt file which is the error I got back from trying to simulate the Mucho Rojo.asc file.

as far as the schematics being correct I believe they are.  I am checking and double checking the schematics I have printed out from tonepad.com

Any help would be greatly appreciated!

thanks,
zpyder

[fxdfxd]

Hi

I try your examples, but I've not the error "node floating" 
But they doesn"t seems to work, or maybe it's only very long (I didnt let the sims run, I stop after few minutes).

And It's seems to me that LTSPICE need a ground in the circuit to be able to run, so maybe you can try to add one ?!?

good luck
-fx

[zpyder]

fxdfxd-

thanks, yea, you're right, I was missing a ground.  But that didn't solve the problem unfortunately...

Could you post any of your .asc's that work for you... maybe I could look at them and see what I'm doing wrong

thanks
zpyder

[fxdfxd]

Ok, I'll try to send some files, but not for the moment, cause i'm at work

-fx

[zpyder]

fxdfxd-

post?

cheers

[Gilles C]

I'm back from a few days out in the woods on the side of a river, and just came back home to check a few things out , read the emails, and I"ll go back there.

But I'm still interested to follow the progress with this program. I hope to be using it when I'm back home for good.

So, from what I can read, more demo files would be good to download.

Gilles

[GibsonGM]

I've had some success with LT, just going thru the 'learning curve'!  Gilles, I think, had mentioned something about the input voltage level...I'd like to see an example of how he lowered his input w/voltage divider to prevent the program from totally clipping the signal and giving no output.     I threw together an NPN muffboost - I think it was from AMZ...has way too much gain, and kills the output.  I did lower some R values to make it work.

The point of that was to see what the double Big Muff tone stack would sound like...it reduces the signal level so much you have to boost it after.

Good program, though...fun and interesting!

[tcobretti]

It seems to me like it would be really cool if everyone posted their layouts for this program to one site so we can share our results.  I'm willing to host the stuff if you guys wanna send me finished schems.

[zpyder]

tcobretti-

I think that's a wonderful idea.  I'm hungry to see how people are actually getting this work with more-than-super-basic circuits.  Plus I think it could be a great way to share some brainstorming ideas!!

Ready when you are

cheers,
zpyder