first layout attempt: Guitar Synth

[choklitlove]

the schematic is from:
http://www.epanorama.rackhost.net/schematicsforfree/Audio/Musical/Circuits/Guitar%20Synthesizer.pdf

and here are the data sheets for the ICs:
http://jameco.com/wcsstore/Jameco/Products/ProdDS/12597.pdf
http://jameco.com/wcsstore/Jameco/Products/ProdDS/45938.pdf


the main thing i was confused about was the power.  i went by the datasheets' Vdd for the power and the Vss for the ground.  i didn't put anything between the battery and the Vdds.  is this correct?  and more importantly, would this work?  be gentle, this was my first go with layouts and the program.

Thanks!

[RaceDriver205]

(blank)

[choklitlove]

if it's not working, here's a link: http://i49.photobucket.com/albums/f295/choklitlove/guitarssynth2.gif

[nelson]

You might want to ground the unused inverters of the 4007.

[choklitlove]

You might want to ground the unused inverters of the 4007.

inverters as in just the rest of the pins?  does it need to happen to the other ic as well?

[choklitlove]

here is an update.  it's a lot smaller, i grounded the unused pins of the 4007 (even though i'm not sure if that's what nelson meant), and i got it down to just 1 jumper.  please give me some feedback!


http://i49.photobucket.com/albums/f295/choklitlove/guitarssynth4.gif

[RLBJR65]

I think only pin 6 or 8 of the 4007 needs to be grounded. Check out this data sheet, you can see it has 3 inverters, pins 3-5, 6-8 and 9-10. http://pdf1.alldatasheet.com/datasheet-pdf/view/26835/TI/CD4007.html

[Quackzed]

wow, nice and compact! i gotta buy some chips!! guitar synth stuff is my latest focus. does it do anything? or is it totally dead...? orientation? bad cap? cold solder joint..  ?   you will fix it... have no fear!

[toneman]

Only the INPUT pins on the unused sections need to be gnded.
Never gnd the OUTPUT pins, as U are just shorting out the IC.
The rule is:  ALL unused CMOS inuts must be tied Hi or Low.
Don't know bout The rest of the PLL.
T

[Connoisseur of Distortion]

when you complete this, please post soundclips. a dead simple guitar synth would be pretty awesome...

[j.frad]

oh i'll be keeping an eye on THAT thread! My microsynth is almost finished but it's a hell of a big build!

[MartyMart]

Inputs are 3 6 & 10 so just looks like 6 need grounding to me.
I may try this on perf/stripboard as I have the chips .....
Perhaps worth making the 100k a pot to vary the basic frequency, may need a limiting
resistor of 10k or something ..?

MM

[choklitlove]

Perhaps worth making the 100k a pot to vary the basic frequency, may need a limiting
resistor of 10k or something ..?

MM

yeah, i was going to add more 'control' by a basic frequency pot and a pot replacing the low pass filter's 15k resistor.  i'll probably wait until this layout is verified, then i'll do that.

explain to me exactly how to add a limiting resistor on a pot.  i get really confused when i try to analyze it...

[MartyMart]

I'm "guessing" values here, but from pin 11 wire a 10k resistor to lug 3 of your 100k pot
and join lug 3 to lug 2 ( variable resistor ) then lug 1 goes to ground.
If this works backwards ( sometimes happens ) then wire it as lugs 1&2 joined with
3 to ground, but version one would seem to be correct.

I'm guessing because i dont know what "zero" resistance would do to the circuit, it
may well be interesting !!

MM.

[choklitlove]

another update: grounded pin 6, moved and made layout smaller.


http://i49.photobucket.com/albums/f295/choklitlove/guitarssynth4_3.gif


thanks for that, marty.  i'll work on that.

i haven't tested this at all.  i don't have the chips yet, but once i get to a good layout point, i'll etch a board, get the chips, then test it.  also, i hope you guys aren't expecting too much from this circuit.  it's not a real synth...

[reverberation66]

  yeah!  I was thinking that 100k should be a pot too, that was what I had in mind...Man, thanks for the layout, I was scoping out the schematic for this the other day and thinking it looked interesting and next thing I know you've posted this layout.  Cool, I ordered those IC's, I'll let you know when I get it built, looks weird aka cool...

[Quackzed]

if it sounds like a synth, it's a synth... 
ok i know im gonna get flack for this lol,
and as a concession i'll admit that i'm not someone who has tested the latest greates guitar synth technology available...but for me, analog "wave folders" and other weird guitar signal manglers
have an immediacy and a certain sensitivity that make them sound "better" than some REAL guitar synths i've heard... give me one "synthy" sounding effect that reacts to my playing and gives me some touch sensitivity and still posesses some of my strings envelope complexity and you can keep all those lifeless midi "note followers". i'd rather have a TONE i can use than a bad approximation of a flute or violin... however i would LOVE a GOOD violin tone, i just wonder if it's a question of trying to derive a more complex signal from a less complex one... ie. is there enough attack information in a pluck to describe all the different variations in a bow.. ? but i digress,
I hope this circuit works out, seems like in effects design -simplicity is popularity!
and this layout is very easy on the eyes, can't wait to hear it's personality! 

[toneman]

hey choklit,
Your circuit is really a "pitch follower".
4 a GuitarSynth, U need envelope triggers & filters & VCAs.
The article says "similar to a synth".
The LowPass filter gets rid of upperharmonics that would false trigger the PLL.
Then the squared-up up guitar frequency goes to the PLL input.
The PLL tries to "lock into" the input freq.
The output of the PLL, Pin 4, is a SQuare wave.
The SQwave out usually should have a buffer opamp.
So, what U will have out is a SQuare wave at the guitar frequency.
Still, an interesting soundmaker.
afn
T

[choklitlove]

i only named the layout after it's author's article.  i don't think "Guitar Synth kind of" would be a good layout/effect name.

anyway, no harm done because i don't believe anyone here thinks it's a real synth.

[choklitlove]

update: added pads for two pots.  i'm not sure if they will work (that is if the layout does), and if they do, they might be backwards.  i pretty much guessed on the VCO pot.  i guess we'll see...

http://i49.photobucket.com/albums/f295/choklitlove/guitarssynth5.gif

let me know if this looks like it won't work, because it probably won't.  thanks!