Guitar-to-MIDI project article

[jman 31]

Sorry, Here my revised schematic. SCHEMATIC

EDIT: Fixed my first post. Sorry about the double post!

[jman 31]

Well, I breadboarded it today with the original schematic and what do you know, no click! So I have screwed up somewhere in my schematic or layout.

[Gurner]

I'd lay money on those LEDs being the source of your click (I can't say why when you've breadboarded it, that the click disappeared - you schematic photo/scan isn't complete).

When the PIC switches on those LEDS, there's a small transient of current running which get's into the PIC VCC rail, this in turn gets into the TL072 supply, which in turn gets into your signal....becuase a guitar signal is so small, this current jolt is right there in with it & gets amplified up big time.

The solution is normally to have a separate regulated rail for your digital & your analogue (and the ground planes come to that) ...or you could disconnect the LEDs!

[jman 31]

Hi Gurner and thanks for the response. I already tried removing the LED's and it didn't change anything. My next thing to try though is to separate the rails like you suggested. I haven't had time in the last few days to mess with it, but that was my next thing to try. You may still be on to something with the LED's, though I'm not sure what. I didn't include them when I breadboarded it.

Thanks,
J

[potul]

Hi J,

What's the difference between the original schematic and yours? I've taken a quick look at both and the only difference I spot is the filtering on the 7805. I think in the original, the 2 condensers are in the output of the 7805 while you have put them in the input.

Potul

[jman 31]

That's pretty much it Potul. I've added an alternate output, but I'm pretty sure that is not what is affecting it. And I don't have the power switch on through the audio jack (seems that should help, not hurt). I've even added the filtering back in like the original schematic to eliminate that difference. I'm afraid it may be my power trace routing on the PCB, but I haven't had much time to look at it this week. I'm hoping to get back on it soon. This is very frustrating. I am working on a surface mount version right now, so I will test that when I get it done to see if it has the same issue. I sure hope not.

[HB]

I've just bought the EPE magazine October 2009 back issue but the software/source code is no longer available to download from EPE's website.  Does anyone know where I can find it (I have searched hard on the Internet) or can someone please post it to download.

[potul]

From this link you can download the one that I modified, but I don't have the original one anymore.


https://sites.google.com/site/potulfx/marketing-docs/G2Mplus.asm?attredirects=0&d=1

[HB]

Thank you very much Potul.

Would you mind explaining the hardware modification that you made for the hammer-on/slide mode selection?   I think you have added a switch so that the comparator input RA1 can be set to high or low, but you also mention including a resistor - is the resistor connected between the switch and pin 18 (RA1) as a current limiter?  What value did you use?

regards

Harry

[potul]

The change you need to do is add a switch and a pull-up resistor. So, RA1 should be connected to either 5v or 0v. I don't remember what position is what... (I think 0v is "legacy mode" and 5v is "hammer on mode")

This version is configured for MCLR pin acting as MCLR, because my programmer requires it. This means you need an additional conection of the MCLR pin of the PIC to 5v through a 10k resistor. If you want to make it compatible with your hardware you may need to change the configuration bits.

[deadastronaut]

 

[Lurco]

Polyphonic without special pickup? Is it real? http://www.jamorigin.com/midi-guitar/

[potul]

wow....
It's not the first polyphonic recognition we see (remember polytune), but for midi.... that's a challenge. I've downloaded the demo to try... tonight I will try to test it.

Mat

[Jdansti]

I'm going to give that app a try. I've got a Sonuus G2M, but it's monophonic and I don't play clean enough for it to sound decent.

[deadastronaut]

thanks to artifus i'm now building the Guitar 2 midi  project...(even though its only mono i'm looking forward to hooking it up and messing around with it as my first introduction to midi guitar)

i have to wait for my 18pin socket for the pic, but other than that its ready to go...

below are the files artifus kindly sent me.




https://dl.dropboxusercontent.com/u/7464107/G2MaPCB.pdf

https://dl.dropboxusercontent.com/u/7464107/G2MaRob1.pdf


@potul/john  did you try that demo plugin?

[Jdansti]

^ I haven't tried the plugin yet. It's been a while since I've used my DAW due to having to overhaul my computer. I hope to give it a try after my wife turns me loose from my remodeling work. 

[potul]

@potul/john  did you try that demo plugin?

not yet. This weekend my home PC decided to stop working... looks like the HDD passed away.  Once I have this fixed I will try

Mat

[deadastronaut]

update on those pdf's..

reverse the 7805. ...other than that all fine.

voila' i have a midi guitar now...its pretty cool with the glide/slide mode...

a little tinkering on resistor values that i had subbed and its good to go i think...

its brilliant playing the synths in cubase/reason etc....lots of fun to be had...even though its mono its great to mix with guitar...or on its own

get it to trigger 5ths and octaves  or sus2's / chords and your laughing.....well worth a build imho...

i'll try and do a vid, but my soundcard doesn't like cubase and windows movie maker on at the same time.. ...

[deadastronaut]

ok really bad phone demo vid...the mics on phones just cant handle it...but you get the idea..

sounds superb in reality..

https://dl.dropboxusercontent.com/u/7464107/mifdimovie1.wmv

[Jdansti]

Very nice Art and Rob!  Sounds great!  Now you can play the oboe! 

How clean did you feel you had to play to get a good sound?  What happens with a little overlap between notes?