Need help with first stompbox

[mogo456]

Hi everybody, i'm new to this forum. I wanted to create my own distortion box and I came up with something really cool. (I think... )

The whole thing was working really well on the bread board but since i've put it in the case, there is a oscillating noise going on all the time.

can the case act as a big antenna since everything is unbalanced??

also, I would need a hand figuring a way to bypass the pedal without having the volume knob affecting the bypassed signal.

hope anybody can help!

Thanks MOG

You can find my schematic on my blog: http://digitalretard.blogspot.ca/

[dwmorrin]

The whole thing was working really well on the bread board but since i've put it in the case, there is a oscillating noise going on all the time.
can the case act as a big antenna since everything is unbalanced??
also, I would need a hand figuring a way to bypass the pedal without having the volume knob affecting the bypassed signal.

Did you ground the casing?  It should work as a antenna to tell circuit what not to amplify.
What does the frequency of the oscillation sound like?  High, low?

Here's a modified version of your schematic with a SPDT bypass that gets the volume knob off the output jack.  With this scheme, you just have to see if the input impedance of the first stage has a noticeable loading effect (loss of tone)... for "true-bypass" get a DPDT.
I showed where you could try putting in bypass caps to try to kill the oscillations.

[Kipper4]

Welcome to the forum mogo

I'm not terribly up on transistor circuits but you may have created an oscillator circuit.
It looks overly complicated to me. I think you could have done more with less parts.
I double the box would act as an antenna. it usually does the opposite. (acts as a faraday cage to shield the circuit within from freqauncys that may affect it.
You could use true bypass as most of us do here
google tonepad offboard wiring. I like the page 5 arrangement where the input is grounded in bypass mode
and if i have any of this wrong i'm sure someone will put me right
Rich

edit
defo ground the case too

[mogo456]

thanks for the answers guys,

I did change the switch to the output side before seeing your post! hahaha it does work. i updated my drawing on my blog. if you are into fishing you'll find some nice spots there as well haha

I'm not sure what is going on with the oscillating: when I power the pedal with a dunlop psu 9V 0.67a i get the tone witch is quite high (around 4kHz) but on the other hand, if I apply power with my DC power supply on the desk, everything is fine....

could it be because the pedal draws too much current?

thanks
MOG

[dwmorrin]

I'm not sure what is going on with the oscillating: when I power the pedal with a dunlop psu 9V 0.67a i get the tone witch is quite high (around 4kHz) but on the other hand, if I apply power with my DC power supply on the desk, everything is fine....
could it be because the pedal draws too much current?

Your pedal is probably only drawing 2mA, most of it being drawn by the LED.  That's not a lot of current.
If a battery works good, and a good power supply works good, then I'd suspect that your dunlop power supply is noisy.  Adding some power filtering might help.  Put 100Ω in series with the power input then a 100µF cap from +V to ground.
Like this: http://beavisaudio.com/bboard/projects/bbp_FilteredPSU.pdf

[mogo456]

Problem solved... thanks for the tip.

Happy new year everyone...

MOG