Tim Escobedo's PWM

[joer0952]

Hello everyone, this is my first post.  Ok well I crated a layout for a Tim Escobedo PWM.  This is the first time I ever made a pedal from scratch so I want to check with people way more knowledgeable then I to see if I did it right, so I don't mess it up big time.  I pulled the info to make the pedal and add all the little dodads, like the led and the dc jack, from different websites since there isn't one complete layout.  So, basically I'm not sure if I did it right.  So, if you have some free time to look at this mess let me know if there are any problems.  I apologize for the mess of wires ahead of time, take pity on me its my first time making a pedal and using this program.
Here is my initial layout (i put this in because it gets more messy with the added switch):

I then added a switch to turn the LFO on and off:

[joer0952]

I know it's alot to look at, but if u get a chance this is the schematic I was working off of:

http://folkurban.com:80/Site/PWM-715.html

[Hides-His-Eyes]

Now you can see why we don't draw the power/InOut/Switching on the layouts, huh?!

[deadastronaut]

wow...thats gonna be a big board...welcome....

i would shrink it down if i were you, it could be a lot smaller.....

isnt there a pot missing?...2x500k 1x100k 1x 10k?...(the pulse width?)

try and use jumpers instead of wires on the board...and try and keep any connecting wires for
pots/jacks/power/ground etc , on the edge holes....

i would use a small toggle switch for the lfo....

it will make it a lot easier to 'read'..

yep,thats why no-one draws the off board stuff...its too much..like wiring spaghetti...good attempt for first go though.
the more you practice with vero design, the better and smaller your boards will be...

have you breadboarded this to hear it first?....

edit: here you go i had some spare time to kill today..so i drew this up for ya...(from the schematic). dont forget cut under cap3..and jumpers under ic's.

[joer0952]

Yea I only put that stuff on was to get insight into wether I did it right since it's my first build.  I plan on making it more compact, i skipped some tracks b/ c I did it quick.  Thanks for the info, I didn't realize there was a 4th pot.

[joer0952]

ok one more question, I built the pedal, and it works except for the fact that only the volume and pulse width pots seem to do anything, when i turn the other two pots they dont seem to do anything.  Anyone have any suggestion as to why the 10k and the other 500k pot dont function?

[Taylor]

ok one more question, I built the pedal, and it works except for the fact that only the volume and pulse width pots seem to do anything, when i turn the other two pots they dont seem to do anything.  Anyone have any suggestion as to why the 10k and the other 500k pot dont function?

The main portion of the schematic shows all the schmitt trigger inputs that aren't being used tied to ground. If you then add the LFO shown in the lower box, you need to disconnect pin 13 from ground. It looks like both your layout and Rob's have 13 still tied to ground but with the parts connected to it. The oscillator won't oscillate this way, so you'll have to disconnect ground from pin 13.

[joer0952]

Thank you for the reply.  I disconnected the wire that connects pin 13 to all the other unused pins and there was no change.  But, pin 13 is connected to a 2.2uf cap that is grounded.  Do i have to remove that ground?  If so what do a connect the (-) end of the cap to?  Sorry if these are stupid questions, but I'm new at this and am trying to learn the ropes lol.

[Taylor]

No, that 2.2uf should be connected to pin 13 the way it is.

I see some more issues, but before I continue, can you tell me whether you're working from your layout or the one deadastronaut posted?

[joer0952]

its actually a hybrid of both, but i figured out what i did.  I removed the wire connecting pin 13 and pin 11, but not the wire connecting pin 13 to the ground to begin with lol.  So, once i removed this wire from pin 13 and connected it to pin 11 all the pots work and it sounds awesome.  Thank you very much for the help, and I learned something!  When IC pins aren't used they are hooked to ground and that must be removed if they are going to be used.

[Taylor]

Pretty much, but I think you only need to ground CMOS inputs, not outputs. Grounding both probably pulls crazy current.

It's also a little different with opamps. You don't want to ground unused ones, instead pull the non-inverting input to 1/2 your supply voltage (vref) and connect the output to the inverting input.

...I realize that info was not necessary here, but it sounded like you were forming a rule in your head and it doesn't always hold true.

[joer0952]

ok thank you

[deadastronaut]

@joer .yay!....glad you got it going....can you post a soundclip of it?.....im dying to hear this?...


@taylor, well spotted, nice one.

[El Heisenberg]

What does this sound like?

[tiges_ tendres]

Sounds like this:
http://www.youtube.com/watch?v=WY2hWE5LeIE