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first layout attempt: Guitar Synth

Started by choklitlove, June 03, 2006, 07:27:46 PM

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choklitlove

#40
June 08, 2006, 03:46:16 PM
okay one quick question:  i thought (for some reason), these capacitors at the input and output to block dc needed to be electrolytic.  am i wrong about this?  the reason i ask is that you said the existing cap i had at the input would work.  thanks again!
my band.                    my DIY page.                    my solo music.

choklitlove

#41
June 08, 2006, 03:58:18 PM
i'll take your word for it.  here's an update with the pulldowns and capacitor and all that.  maybe this one will work...


http://i49.photobucket.com/albums/f295/choklitlove/guitarssynth8.gif


http://i49.photobucket.com/albums/f295/choklitlove/guitarssynth8nomods.gif
my band.                    my DIY page.                    my solo music.

gez

#42
June 08, 2006, 04:09:18 PM
Cap 6 needs to be between the output (pin 4) of the 4046 and lug 1 of the pot.  If an electrolytic is used, the + leg connects to pin 4 and the - leg to lug 1.

Otherwise, looks good.
"They always say there's nothing new under the sun.  I think that that's a big copout..."  Wayne Shorter

choklitlove

#43
June 08, 2006, 04:15:27 PM
since pin 3 and 4 are connected, running it from the 3rd like i did should be the same, right?  if not, why?
my band.                    my DIY page.                    my solo music.

gez

#44
June 08, 2006, 04:16:04 PM
Quote from: choklitlove on June 08, 2006, 03:46:16 PM
okay one quick question:  i thought (for some reason), these capacitors at the input and output to block dc needed to be electrolytic.  am i wrong about this?  the reason i ask is that you said the existing cap i had at the input would work. 

All caps block DC.  Electrolytic caps are only used because there's nothing else that can be made that small with such high capacitance, so when you need a big cap electrolytic is all you have really.  It's best to make output caps large as you have no idea what the input impedance of whatever follows is.  If it's low, then a small cap is going to limit bass.  Inputs with high impedance (not really the case here incidentally) don't require such large caps, so electrolytics can be avoided.
"They always say there's nothing new under the sun.  I think that that's a big copout..."  Wayne Shorter

gez

#45
June 08, 2006, 04:17:03 PM
Quote from: choklitlove on June 08, 2006, 04:15:27 PM
since pin 3 and 4 are connected, running it from the 3rd like i did should be the same, right?  if not, why?

No problems, do it (I just used the given pin on the schematic to keep things simple).
"They always say there's nothing new under the sun.  I think that that's a big copout..."  Wayne Shorter

gez

#46
June 08, 2006, 04:18:06 PM
Sorry, I think it was ok in the first place...all these damn components obscuring traces!  Hold on, I'll check again.
"They always say there's nothing new under the sun.  I think that that's a big copout..."  Wayne Shorter

gez

#47
June 08, 2006, 04:20:06 PM
Maybe it's an optical illusion, but on my monitor it looks as though pin 4 is still connected to lug 1. :icon_confused:

If not, my apologies.  If so, cut the link.
"They always say there's nothing new under the sun.  I think that that's a big copout..."  Wayne Shorter

choklitlove

#48
June 08, 2006, 04:25:25 PM
Quote from: gez on June 08, 2006, 04:20:06 PM
Maybe it's an optical illusion, but on my monitor it looks as though pin 4 is still connected to lug 1. :icon_confused:

If not, my apologies.  If so, cut the link.
i know, it's weird.  there's no trace, the cap's just shaded on the negative side, so it's hard to see.  maybe i'll upload a pcb soon, but i've been avoiding it so far because the project's not done.  i hope we get this thing going.  thanks for all of your help!
my band.                    my DIY page.                    my solo music.

gez

#49
June 08, 2006, 04:30:48 PM
Quote from: choklitlove on June 08, 2006, 04:25:25 PMmaybe i'll upload a pcb soon, but i've been avoiding it so far because the project's not done.  i hope we get this thing going. 

Good idea.  I haven't really checked the layout over that thoroughly, but just glancing over it things look ok, so it should work as intended (though that might not be that great).
"They always say there's nothing new under the sun.  I think that that's a big copout..."  Wayne Shorter

reverberation66

#50
June 08, 2006, 04:35:23 PM
Man, I've been following this thread with interest, eagerly awaiting those IC's in the mail so I can try this thing, keep us posted.  I'm gonna do a vero layout from your layout and the schematic.  And no my expectations aren't too high, lol, but I tend to like things that sound weird...

choklitlove

#51
June 08, 2006, 04:45:10 PM
this layout is still not verified.  please don't expect it to work yet...

http://i49.photobucket.com/albums/f295/choklitlove/guitarssynth8pnp.gif
my band.                    my DIY page.                    my solo music.

j.frad

#52
June 09, 2006, 03:18:59 PM Last Edit: June 09, 2006, 05:17:38 PM by j.frad
Can't wait for it to work! my microsynth is giving me a hard time troubleshooting...

choklitlove

#53
June 09, 2006, 11:31:31 PM
where's rick?  i won't be able to get the parts until sometime next week, so i'm curious if the revisions we've made since his last post will make his work.  i wish there was a store that carried those ic's.  i'd have the sumbitch working by now.

rick!!!
my band.                    my DIY page.                    my solo music.

RickL

#54
June 10, 2006, 02:13:54 AM
I haven't done anything else to mine since my last post. I should try adding a cap at the output but I don't think it will make much difference. Mine doesn't have a pulldown resistor at the input but that won't effect the sound either. I'll try to get to it this weekend. What I've got so far may be as good as it gets.

I'm in the last stages of training to do a half Ironman on the July 1st weekend and my weekends tend to be filled more with sweat than solder.

RickL

#55
June 10, 2006, 07:29:24 PM
Update - I added a 1uF non-polarized cap at the output and fiddled some more with it and it appears to at least somewhat work.

With no input from the guitar (i.e. guitar plugged in but not playing anything) it oscillates all by itself, pretty much random noise like you might hear when twiddling the dial on an AM radio late at night.

Single notes from the guitar mostly silence the random stuff and seem to follow the pitch of the guitar reasonably well. With the VCO and Frequency pots turned down it sounds like a square wave distortion. Turn up the Frequency and some overtones start to creep in. If you turn the Frequency pot up too high (smaller resistance) it won't trigger and you're back to random noise. Turn the VCO pot up and you get more overtones and less square wave. Turn it up too much and you're back to random noise.

It works better above about the fifth fret, especially with the pots turned up and it doesn't like chords. The only way I can imagine using it live is with a noise gate set with a fairly high threshold, or turning it on exactly when you hit a note and never stop playing until you turn it off.

I guess it sounds a bit like an analog synth, more so with the pots turned up a bit. It will never be more than a novelty but it was easy to build and you'll have the only one in town.

choklitlove

#56
June 10, 2006, 07:34:46 PM
that sounds about right.  in the article it states that if the 15K resistor at the VCO is increased, it will oscillate without any input.  well, i'm glad that it works at least a little.  when i build it, i'll try it without the mods, and maybe i'll get it to be a little more functional.  thanks rick!
my band.                    my DIY page.                    my solo music.

nag hammadi

#57
June 21, 2006, 07:37:13 PM
how is this coming along?  any news or improvements?

in the face of you all i stand defiant - subhumans

choklitlove

#58
June 21, 2006, 08:40:54 PM
i have just made a full layout and it's here: http://geocities.com/worthekik/guitarsynth.html

unfortunately, it's still not verified.  the ics should be here by the end of the week, then i'll get crackin first thing.  i'll post here as soon as i have any news.  thanks for the interest and help everyone!
my band.                    my DIY page.                    my solo music.

toneman

#59
June 21, 2006, 10:51:10 PM
Hey choklit, 

200dpi dosen't give U a "size" of the picture.

Just print the layout reduced/enlarged until the ICs line up on their tenthinch  (.1) centers.

afn
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