Scratching sound from a pot

[zener]

I breadboarded a basic wah circuit from GEO. I used 2n3904 for the trannies and an output transformer as the inductor.

First, the wah effect doesn't seem to be there until you get the pot to 5k - 0k towards the first lug.

Second, as the pot rotation nears the end towards the first lug, there's scratching sound and it disappear as it reach 0k or full rotation towards the first lug. The same thing happened when I turn the pot from 0K clockwise. The scratching sound is somewhere from 0k - 5k from the first lug.

First, I measured the pot with a multimeter and found nothing wrong. I thought that it might be dirty, so I just took another 100k and there still the scratching sound.

As for the transformer, I do not know the readings in it. It produces a wah sound at the end of the pot's turn but seems to be not enough to emulate those commercial ones. I'm opting to get another one or two have them in series.  

Thanks for any help.

Zener

[ExpAnonColin]

Bad pot, sounds like it.  Electric contact cleaner could help.

-Colin

[Jered]

Some where in your circuit your getting DC to your pot. Leaky cap?
  Jered

[Alpha579]

DC to the pot would explain the scratch i believe, but that wouldnt be why it cuts out...I had a pot like that on my guitar once...replaced it and it was fine...

[zener]

I figured it out already. Both of the pots I used are dirty in the same spot in its rotation.

Thanks for all the replies.