Tooo many grounds?

Started by philbinator1, February 12, 2010, 08:31:53 AM

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philbinator1

had another go at building this Assassin fuzz with vero..lo and behold, still not working, although the led lights, and when i turn up real loud i can hear the vol/gain pots and sludge switch doing something in the background when i operate them..i even get semi-clean signal if i turn up really REALLY loud.  anyway i have 7 grounds (!) coming from the vero/pots/sludge switch/output jack and i have them all going to the inputs sleeve...but that seems odd to me.  is that odd to you guys?    ???
"Hows are we's?  We's in the f*cking middle of a dinners meal!  Dats hows we am!" - Skwisgaar Skwigelf

anchovie

I'd recommend posting this in the thread you had earlier about building this. Then people who might be able to help won't have to hunt around for schematics and layouts. :)
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GibsonGM

Typically, I'd set up a place on the board for all those grounds, and then run 1 conductor to the jack from there, 1 to the power supply too. But, as long as they're all getting there, it shouldn't be TOO much of an issue. It would be hissy noise due to ground currents rather than the circuit not working...it should just work and be noisy if grounds are an issue!  Perhaps there are so many there's not good contact?

Too much wire (resistance) in the ground circuit can result in a swamp of currents flowing in there, adding a lot of noise. 
I'd suggest audio probing the circuit to see where it goes from decent guitar signal to 'not really working'!   And check if the transistor or whatever (don't know the circuit) is in backwards....
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R.G.

Quote from: GibsonGM on February 12, 2010, 09:16:46 AM
Too much wire (resistance) in the ground circuit can result in a swamp of currents flowing in there, adding a lot of noise. 
As I read that, I think you meant that too much resistance in a ground path can cause the currents that are going to flow there anyway to generate noise by Ohm's Law - V = I*R.

More wire adds resistance only very, very slowly if it's not hair-fine copper. Star grounding (one ground return per using device, separate ground for each ground "user" is one way of guaranteeing that no interfering ground noise can be generated *if done properly*, but then I guess those last words apply to all grounding schemes. However one badly soldered joint adds a huge amount of resistance to that path.

QuoteI'd suggest audio probing the circuit to see where it goes from decent guitar signal to 'not really working'!   And check if the transistor or whatever (don't know the circuit) is in backwards....
You are so, so right on this one!
R.G.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.

philbinator1

Quote from: anchovie on February 12, 2010, 09:14:21 AM
I'd recommend posting this in the thread you had earlier about building this. Then people who might be able to help won't have to hunt around for schematics and layouts. :)
Thats a good idea James, its already started so i'll do it next time.   
"Hows are we's?  We's in the f*cking middle of a dinners meal!  Dats hows we am!" - Skwisgaar Skwigelf

philbinator1

Quote from: R.G. on February 12, 2010, 09:35:07 AM
Quote from: GibsonGM on February 12, 2010, 09:16:46 AM
Too much wire (resistance) in the ground circuit can result in a swamp of currents flowing in there, adding a lot of noise. 
As I read that, I think you meant that too much resistance in a ground path can cause the currents that are going to flow there anyway to generate noise by Ohm's Law - V = I*R.

More wire adds resistance only very, very slowly if it's not hair-fine copper. Star grounding (one ground return per using device, separate ground for each ground "user" is one way of guaranteeing that no interfering ground noise can be generated *if done properly*, but then I guess those last words apply to all grounding schemes. However one badly soldered joint adds a huge amount of resistance to that path.

QuoteI'd suggest audio probing the circuit to see where it goes from decent guitar signal to 'not really working'!   And check if the transistor or whatever (don't know the circuit) is in backwards....
You are so, so right on this one!

yeah i don't have really thin wire, just the 22 gauge stuff from small bear...maybe i'll try some diff grounding points for diff components?  is that what you mean?  i had Rick Holt (the designer of the "Assassin of Silence" fuzz) checked my vero...heres the link (sorry about the diff link, i'll know better next time  :)  http://www.diystompboxes.com/smfforum/index.php?topic=81179.0
"Hows are we's?  We's in the f*cking middle of a dinners meal!  Dats hows we am!" - Skwisgaar Skwigelf