Not so true Bypass

[sovtek50]

Has somebody ever had the problem with selfmade stompboxes, that the effect is still slightly audible when the true bypass is activated? How the hell can that be and what can be done about it? I'm having this with an otherwise fully functional Tim Escobado's Ugly Face, and lately with a "Robovox"-Effect, built after a schematic from a Brazilian electronic magazine. Both of them have a frequency pot which affects the still audible (when bypassed) effect tone.

[Gringo]

Have you tried grounding the input of the circuit when bypassed?

[petemoore]

I think the timer puts out some 'stuff' that can get into the BP line inside the box.
 I'd try what Gringo suggested, you should be able to tell with a test wire, alternately adding shielding to the input and output wires inside the box [shielded box?] may help reduce exposure to the timers rf output.
 Also try turning the pot that sets the min 'takeover amplitude'...the one that makes the oscilator active when no input is present, turning that all the way down may stop the 555 from switching and stop the noise.
 Because these are easy to try, and I'm unsure that the 555 is causeing the noise, I typed them out.

[casey]

that robovox thing sounds cool....where can i find a schem. for that?

[Paul Marossy]

I had a similar problem on my Shaka Tube rebuild. I would get an oscillation from the circuit that would somehow find its way into the signal path when bypassed, but it did not oscillate when the effect was engaged. I revised it to a grounded circuit input true bypass scheme, and the problem was solved. Hopefully, in your case, that will fix it.

[sovtek50]

Thx for helping me out so far.
For Casey and all others interested, among here's the Robovox-Source:

http://www.geocities.com/munkydiy/schematics.html

[casey]

thanks....it looks interesting...

[sovtek50]

Pfffft.... last night I tried everything with the Robovox (CMOS 4016). Different types of ground connections, shielded cables...didn't do it. Maybe it's unclever parts placement on the board. Could it be the caps shouldn't be too close to the chip? Thanks for Your time. Any last advice before I'm giving up?

[Travis]

Grounding the effect input doesn't get rid of the bleed?

Sometimes something as simple as using the outside poles of a 3pdt for signal, and the inside pole for the LED can clear up a significant amount of oscillation/bleed.

Have you tried a different switch?

Have you poked around inside of the bypassed effect to see if wire movement can produce any change in the bleed.

Crazy gain circuits (like the Uglyface) really need the grounded input or output to keep from oscillating and bleeding into the dry signal.

[makkimo]

got the same problem with my uglyface still bleeding when bypassed
i know it's a very stupid question but when you say grounding input you mean ground the input and output jacks or something different???
:oops:  :oops:  :oops:
thanks

[bioroids]

Hi!

Are you using shielded cables for the internal connections? In particular for the effect input and all the bypassed signal path?

Luck!

Miguel

[erio fraga]

makkimo

Answers can be stupid, never questions.

Take a look in  http://www.geofex.com/FX_images/stompsw.gif  and you'll find what means ground the input.

Rgds

Erio

[makkimo]

thanks a lot and tears of gratitude openly!!!!!
i will try my best

[RLBJR65]

sovtek50 try this thread for the robovox.
http://diystompboxes.com/sboxforum/viewtopic.php?t=24124&highlight=robovox