How do you do your grounds?

Started by janus, February 22, 2006, 02:40:51 PM

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Meanderthal

#20
 Ok, I made a couple little drawings to help explain here...

1. The ground loop. Here we have everything connected to the pcb. Note that the input and output jacks are connected thru the chassis(the aluminum enclosure itself), and also thru the pcb.






2. No ground loop. Here the input jack is grounded thru the chassis alone, eliminating the ground loop.







If you start working on AC circuits this becomes much more important.


I am not responsible for your imagination.

rogeryu_ph

Thanks Gaussmarkov to your reply.
Meanderthal, as per your description of the ground loop and no ground loop what then the star grounding used in the Tonepad project call? Is it ground loop? If your not familiar to the Tonepad project, the project uses the input jack as the star ground.. This technically I don't know if it is a ground loop or no ground loop. I only use wire tapped from input jack connect to output jack and both jack were isolated from the chassis.  Is this ok?. Also, can we use output jack as the star grounding? Co'z some say can. Thanks in advance.   

Meanderthal

 Yes, isolated jacks are ok, and no, star grounding is not going to create a ground loop, rather it's going way out of the way to avoid one! Keep in mind, though, that if your jacks are isolated you should connect ground to chassis at some point so you have shielding, which is much more important than worrying about a ground loop in a stomp box! In fact, if you have isolated jacks, you shouldn't have a ground loop anyway at all unless you have a wacky layout or something...
I am not responsible for your imagination.

rogeryu_ph

Thanks, Meanderthal. My jack are isolated co'z i'm using temporary plastic box as the casing, now as you said I should connect the ground at (chassis) or some point so I could have shielding, but mine is plastic box so where should I connect the ground? Thanks again....

Meanderthal

 Hmmm... in that case you'd have to line the enclosure(lid and all) with aluminum or copper foil. The idea is to surround the circuit with ground, blocking RF interference. You can't solder to aluminum though, so you'd have to attach ground to it with a screw or something.
But, if you build it and it dosen't pick up weird buzzes, hums, or radio signals, don't worry about it, especially since the plastic enclosure is temporary. Some circuits seem to be pretty quiet without shielding for whatever reason, and others are like radio recievers, especially high gain distortions. However, if the circuit actually calls for star grounding it must be pretty sensitive, so ya better shield it!
I am not responsible for your imagination.

rogeryu_ph

Meanderthal, Thanks.. So far in the plastic box no weird frequencies or hum... But time when I got a die cast casing should I ground the input or output jack with the case? Again thanks

Meanderthal

 If they're metal jacks they will be grounded to the enclosure just by being attached to it.
I am not responsible for your imagination.

rogeryu_ph

Thanks you so much Meanderthal.... :icon_biggrin:

Meanderthal

 The funny thing is, I have a bunch of those Dano plastic enclosure pedals and none of them pick up stray RF, not even the Fab Metal. Maybe the tiny SMD components don't have enough surface area or something... But for that matter the only noise that bugs me about Arion effects is hiss...
I am not responsible for your imagination.

doug deeper

i run a peice of copper wire along the bottom of the board,
then connect that to the input jacks ground, then run any off board grounds to the jacks as well (input or output depanding on which is closer)