Frequency analysis

[Dimitree]

Hi everyone
I was wondering if there was a software that let simulate the guitar signal inside a circuit, watching the frequency analysis. for example, I'd like to draw a circuit and then wathing how the signal is changed adding a resistor or a capacitor, or changing values, and so on.
any suggestion?
thanks and sorry for the bad english

[crane]

The short answer is - yes, there is such software.
The more useful answer is - any spice sofware will do. You can try pspice or LTspice (The first one has a free student version, the second one is free) or Proteus (this one isn't free but it has nice features - for example using a .wav file a input signal)

[Dimitree]

many thanks
I'm trying those 2
what kind of input should I use as generator, in order to simulate properly a guitar?

[ashcat_lt]

Here's one that's already built in a spreadsheet.  If you download it, you'll have to allow the macros to run.  I know the author for years from the guitarnuts forum, and definitely trust his code.  

Here's a screenshot:


Even if you don't want to use his thing, but want to build your own, the picture answers your question.  To sim the pickup you need a tone generator (I use a 1V step function  in 5spice) in series with an inductor and a resistor which are both parallel to a capacitor.  The DC resistance (the value for the resistor) is usually pretty easy to get for a specific set of pickups.  It's a little more difficult to get the right inductance and self-capacitance.  JohnH has included in his spreadsheet a number of "presets" for different common types of pickups, which make a pretty good starting point.  Definitely don't forget the cable capacitance and amp input-Z (C4 and R6 above) as they both have a pretty dramatic impact on the response.