Wah Questions

[zer0_c00l]

Hi, I made a Wah basic circuit from tonepad (this one: http://www.tonepad.com/project.asp?id=61 )
I incorporated it in a Korg Volume pedal and it doesn't work, if I plug in the guitar and then the amp jack it makes a lot of hum, if I put only the output jack it makes less hum but it continues with some hum, I didn't use 100% the same components in the schematic, heres the diferences:

1- The pot included in the volume pedal is a stereo/double 50K so I used only one part of the pot (like a normal 50K pot) instead of the 100K recomended one... I think this only affects the sweep change and has nothing to do with the hum...

2- I used 2n3904 transistors instead of MPSA18 ones I think it doesn't affect much the sound or anything...

3- I don't know what is the inductance of the inductor I used... First I ripped one of of a Relay, It made the noise and it only needed to have the output jack plugged in... then i changed it to another one a little bit smaller and it made hum only if I had the input jack and/or the DC jack plugged in.... I think that changing the inductor shouldn't make noise only would make it sound not as it should...


What can be causing the super amount of hum and not letting the effect work

[petemoore]

What can be causing the super amount of hum and not letting the effect work
  Manything, sounds like maybe a lifted ground.
  "Beep the DMM leads together" [set to diode check setting " -->l-- ".
  Clip the black DMM lead to a ground, test that the board connections follow all points marked ground on the schematic.
  Read, follow the debugging sticky thread instructions.

[zer0_c00l]

Can in be any other thing instead of that? that's what's bugging me, i tried to check everything and it's all ok... =O

[zer0_c00l]

It's when I have only the output and DC jack plugged it makes a little hum but when I touch with my finger anywhere it makes Hum like if the input jack is plugged....

resuming it only makes hum and everything I tested seems OK... I even changed jacks and etc...

[petemoore]

  I know what kinda drag that can be.
  I sat with a Small Stone last night and day.
  No matter how many times I tried, it didn't function properly.
  Then I started with my signal injector, thumb-screwdrivershank {Only use this at 9V or risk lethal voltage}, the jack...the switch...the booster I added...ok ok ok..
  then on to and in to the PCB after night and mostly all day, I noticed 1/2 the phase stages seemed dead.
  The guitar was coming throughthough.
  So a twist on the Debugging thread [only use at low voltage] is what got the signal 'pushed through' the circuit...someone had soldered the daughterboard lead to the wrong resistor, instead of spanning the cut/splice point I made in the PCB, it just connected the in/out of the 2 new stages.
  The fix only took four or so minutes to change, because I did it again...whoopsie...easy does it with the quickness, real easy misses, it still doesn't go there.
  I've had debugs take 4 days to never, probably by way of missing that one thing, catching it on the 83rd debug, and a time when I put it on wrong.
  Shoestrings...without critical debugging information, there is no way to tell...still kinda sounds like a description of an open ground though, possibly something else.

[zer0_c00l]

Q1
E - 0.05
B - 0.66
C - 4.93

Q2
E - 3.41
B - 3.91
C - 7.22

D1
A - 0.00
K - 7.58

Inductor
It measures 0.66 in any of the lugs

Voltage at the circuit board end of the red battery lead = 8.04
Voltage at the circuit board end of the black battery lead = 0


Tested with a battery that measured 8.06V

[David]

It's when I have only the output and DC jack plugged it makes a little hum but when I touch with my finger anywhere it makes Hum like if the input jack is plugged....

resuming it only makes hum and everything I tested seems OK... I even changed jacks and etc...

You have a problem with audio ground somewhere.  The hum is the giveaway.

[zer0_c00l]

Yes, you are right, after all it was only the f*** cable that goes to the amp, it was witing for me to making a new effect for stoping working, thanks anyways...

it still makes a bit buzz but i believe that's because its made only for testing and so i made it out of the enclosure...

other problem its the inductor, seems to be hard to find... the one I canibalized from a relay seems to work minimaly good but i think it doesnt wah enough...