Colorsound wah without wah

[cjtonic]

Hi all,

first of all. What a great forum. Glad i found it. Tons of inspiring ideas even for an electronics dummy like me.

I tried to build the colorsound inductorless wah from this scheme http://www.diystompboxes.com/smfforum/index.php?topic=25279.msg165637#msg165637

After some obvious errors from my side i am now pretty sure that my soldering etc should be ok. Thing is that i don't get a wah sound out of it - just something that sounds like a fixed lowpass filter. Nothing happens when turning the sweep pot.

Do you have any ideas what could be wrong? Anything i can check, any voltages to measure and where?

Any help would be much appreciated.

Cheers
C.J.

[cjtonic]

Forgot to mention. I used a 2N5089 if that is of interest...

[Rafa]

Hi, great to have you here:
For your pedal.
Read the debugging part there it tells what voltages to measure and then you post them here and someone who knows much about electronics, not me ofcourse could have an idea of whats happenig
Cheers
Rafa
PD:Any dobut just ask

[John Lyons]

Hmmm
Make sure that the pot is wired with one outer lug to ground and the other two lugs wired together and to the 470 ohm reisistor. It's possible you have the pot wired in permanent heel down position... If the effect is reversed (toe down is bass...) then just reverse the outer lugs wiring making sure to reverse the jumper between the middle and outer lug.

When you get it going there a nice modificaction to make. Put in a 100K trim pot on the board (or on the top panel! ) This is a resosnance control to make the effect sharp and out of control all the way to oscillation or smooth and a subtle wah.

John

[cjtonic]

qwer

[cjtonic]

Hi guys,

man, that was quick. Thanks a lot for the fast response.

I just checked the pot and it looks ok. one outer lug to ground the other two connected.

And i just started measuring. Here is what i get:

at the trnsistor:
E (the one going to ground): 0V (strange !)
B (the middle one): 0.5§ V
C (the one that goes to 5.7 M resistor): 8.16

Another strange one seems to be the 0 V i get after the 470K that goes to the pot. There should be something, right?
Before the caps there i get 0.52V on the 2n2 side and 0.39 on the 6n8 side

Between the 180k resistors gefore the 15nF cap i get 0.45V

Does that help you guys? If not i will post more. There's plenty ;-)

Cheers,
C.J.

[John Lyons]

Maybe a typo but the 470 before the pot is 470 ohms not 470K.

John

[cjtonic]

Hi John,

no, it wasn't a typo. it was me :-(

But thanks. Changing the resistor to the correct lower value did the trick. Maybe the idiot wah would have been a better choice for me ;-)

Thanks again for your help.
Cheers
C.J.

[oldrocker]

Remember in place of the 100k pot you can use an LED/LDR.  I installed mine into a sewing machine pedal with a 50k pot in place of the 33k to ground.  I used the foot control to block light instead of turning a pot to get it to wah.