some mods to the escobido PWM pedal

[pinkjimiphoton]

hi, built this over the last day or so, and was playing with the circuit some trying to get it to work.
it worked as built, but i didn't think it was working right, so i started searching thru the forum and read a dozen or so posts on this pedal,
and set out to figure out a way around some of the problems.

one thing i found useful was to add a 100 ohm resistor between pin one and the wiper of the width knob, that seemed to make it behave a bit better.
to me, this knob is almost useless, and it's difficult to tell whether it does anything or not...and seems kind of intermittent at best, unless i screwed something up.

also, found the output of the pedal really low...checked voltages and continuity, no shorts, and a very gated blatty sound with zero dynamics.
bridging pins 1 & 2 of the 40106 brought the gain way up...to an almost overkill level. i kept it that way, i liked the sound better with more balls.

finally, just fooling around, i bridged pins 7 and 8 of the 40106 and got a BIG boost, and a 100% increase in sustain, particularly on the e and b strings.
it's really only shorting pin 8 to ground, but i decided to play with it a little, and bridged it with a bunch of resistors, from 100 ohm up to 100k...what seemed to work best was a 47k
resistor, so i added it in. big improvement, the sustain is now really good, but seemed a little muddy, lost some of that extreme high end sputter and breakup. so i added a .01 mf cap to the 47k resistor in parallel, and that seemed to do it, for me, at least. i did lose some of the noise factor, so may eventually put this rc network on a switch...

but now, it sustains like a big muff almost, and is RIDICULOUSLY dynamic. you can actually use your guitar's knobs, and they do something. as you turn down your volume pot, it cleans up nicely, and crunches when ya hit it hard...and you can turn it way down and get pretty clean, almost glassy but not overly bright tones....and, again, your playing dynamics can make it crunch.

i dunno if it's RIGHT, but to me, it's more useful now.

but...i can't for the life of me tell if the pw pot actually does something or not, is this supposed to be extremely subtle? this thing seems to be brutal sounding prior to my mods, so i was kind of expecting the pw to be over the top. it DOES seem to do "something", but i couldn't say what. thinking about adding the lfo circuit dead astronaut and others have put on layouts on a secondary board, hoping that that may make things more noticeable with the modulation, but i just built an uglyface, don't see the need to add the lfo, it just makes this thing sound like the ugly face in the clips i googled.


so,....anyways...any thoughts? does what i describe make any kind of sense?
i'll try and up a vero layout shortly.

thanks
jimi

[pinkjimiphoton]

here's a layout of this thing, verified. i don't know if it's the same pedal anymore, but to me, it's very useable now.
if you build/breadboard it, please let me know if ya find any issues or bugs that i may have added by mistake.
i still have no idea if the pwm pot really DOES anything...it's rather subtle if it does... but this modded version is a really nice fuzz/distortion, sustains great, unlike the original,
and has a good bit of balls.
anyways...

[deadastronaut]

hi jimi.

checkout some youtube pwm pedals...should give you an idea of what the pwm knob should sound like..

should be very squishy...(i know bad example.. )


soundclip?...

[pinkjimiphoton]

hi rob,
i listened to a bunch of them on you tube, yah, i guess it's working...kinda. think i toasted the 40106 possibly messing around with it. gonna have to wait and try a new one...for now, this project will take a back burner. i ended up modding it with a pair of switches, one to bridge pins 1&2 on the 40106, and a second to add the rc network across pins 7&8.
with both off, it's a pretty sick octave fuzz almost...when kicked in, it suddenly gets some manners, when both are kicked in, it gets into some territory where it could work as a standard fuzz/distortion pedal.

ended up with a 50k volume pot, too, as i was too lazy to go get a 100k one.

i'll try and up a couple clips or a youtube tomorrow!

[tiges_ tendres]

Here's a clip of mine:

http://youtu.be/ERSErd5j-gY

With the oscillator stuff.
http://youtu.be/WY2hWE5LeIE

[pinkjimiphoton]

never saw the first one, thanks...yah, that's pretty much what mine sounded like before i damaged the 40106 chip....ooops...

i didn't build the lfo in this one, maybe the next one...but with the lfo it's close enough to the ugly face i may just stick with this one i built as a completely different animal.

i shot a video demo, it's uploading to youtube now.

[pinkjimiphoton]

video:

http://www.youtube.com/watch?v=7qna3Z0ETN0