TESTING HOW TO -- using function generator / signal generator and PC oscilloscope or Spectrum analyzer -- how to? what to?

[j-pee]

hi,

If this was still the old days, without phone-computers and applications, and open source software and Linux,
I'm sure, many people wouldn't even think of oscilloscopes and wave forms whatsoever...
and just build the pedals and use them... play music, that is...

BUT... given that.. a function generator kit from ebay costs but a few potatoes (even though it has a fake Chinese XR2206 chip in it),
and that for Android, for example, one can download a decent spectrum analyzer in but a few seconds time, for FREE (thanks to Carl Reinke, for example, who created Spectroid),
not to mention Keuwlsoft's Dual Channel function generator,
and that even real-life Oscillators can be purchased for very reasonable sums, as Chris60601 mentions it here:
http://guitar-fx-layouts.42897.x6.nabble.com/Do-you-guys-use-an-oscilloscope-tp31327p31765.html

or Ciaran Haslett here:
http://guitar-fx-layouts.42897.x6.nabble.com/Do-you-guys-use-an-oscilloscope-tp31327p31328.html

... one gets totally curious about testing! :)

and by testing I don't just mean checking if a circuit works...
but testing how it works, what it does to sound...
how a tone stack shapes the sound, for example...

I believe that in most cases people talk about what a circuit does based on modeling programs...

..........................................................
ANYHOW, the question is:

how to test your circuit?
what to test?
how to analyze its behavior?
how to compare two circuits?
and whatever exciting things one could do?
using FREE software and simple devices...? :)

..........................................................


I have seen these threads (and liked them very much):

http://guitar-fx-layouts.42897.x6.nabble.com/Stripboard-Breadboard-Interface-for-beginners-td5260.html

http://guitar-fx-layouts.42897.x6.nabble.com/Do-you-guys-use-an-oscilloscope-td31327.html

http://guitar-fx-layouts.42897.x6.nabble.com/Has-anyone-hacked-an-old-iPad-into-an-oscilloscope-td36569.html

...............

the following pics are illustrations of the free devices / applications I've collected just lately








any input is welcome :)
any help would be great! not only for me, hopefully :)

[Travis]

I built four condenser mics where I had to inject a test signal into the preamp and monitor the output on an oscilloscope. I did this using my apogee duet and DAW (Logic). Logic and most DAWs will include a basic test oscillator. For the oscilloscope there are a couple companies out there making oscilloscope plugins that can be added to your DAW. I can’t remember the name of the one I used but it was “blue” something I think and there was an option for a free trial version.

However I think you may really like Room EQ Wizard. This will let you do some useful measurements like sweeping through the whole audible spectrum to measure frequency response etc.

I think one of the more exciting things you could do would be to analyze the harmonic content added by an overdrive pedal for example. In that sense you could potentially alter not only the main tone of the pedal but also possibly elicit some positive subconscious reaction to the harmonic content