Newbie Ground Questions

[JazzBass]

Hi all,

My first time here and first attempt at building boxes.

I'm going to build a A/B box of sorts to allow 2 basses to use 1 amp.  It will have LEDs to show me which bass is selected, powered by a 9v batt.

I was also thinking of adding another output for my tuner, but not sure yet.

I have a drawing all ready to go and have the majority of my parts from radio shack.

What concerns me is grounding.  I'm having a very hard time understanding how it is done and how it can be done.

What I will have is this:

2 mono jacks as inputs for the basses

1 stereo jack as output to my amp.

Ok, I was planning on running the LED grounds to the stereo jack ground and the batt ground to the ring terminal.

Alright, now, what I'm wondering is if I need to run grounds from the input jacks to the ground on the stereo output?  I've read so much about grounding from the input jack and whatnot that I am totally confused.

Also, when using boards for the circuts, what makes a ground a ground on the board.  I know it's better to connect all grounds in the same section of the board together.  Is there another piece I'm missing or since you are running a wire from a grounded jack, that's what makes it grounded?

Thanks very much!
JB

[robotboy]

Here's a simple A/B box that's very easy to make.

http://fulltone.com/PDfFiles/AB_switcher.pdf

Hope that helps.

[JazzBass]

Here's a simple A/B box that's very easy to make.

http://fulltone.com/PDfFiles/AB_switcher.pdf

Hope that helps.

Thanks for the link.

That's pretty much what I want to build.  I was just asking the grounding questions for my own knowledge and benefit.

What is the plastic lug where the picture showing the negative connection?  Is that the power source?

Thanks,
JB

[robotboy]

Yeah, that's a 9VDC jack. You don't have to use one if you don't want to. You can just use a 9V battery if you don't feel comfortable having your first build plugged into the wall. As far as grounding in general is concened, all the ground points in a circuit are connected together. The sleeves of your input and output jack go to ground as well and -9V of the battery goes to the ring of the input jack (assuming it's a negative ground circuit). This is assuming you're just using a battery. If you're using a 9VDC jack and battery, the setup is a little different. If you're using a metal enclosure and switchcraft jacks, the enclosure will be grounded through the jacks, so you don't have to worry about running an additional wire from ground to the enclosure. Some people worry about a ground loop because of both jacks being connected to the enclosure; however, most people don't, and generally it's not a problem. If you want to get pedantic though, you can isolate one of the 1/4" jacks using a variety of methods, so that the enclosure is grounded at one and only one point. Here's a diagram showing a typical true bypass switch wiring scheme.

http://www.diystompboxes.com/beginner/circswled.jpg

I usually have all my ground points connected at the bottom of my perfboard and all my +9V connections at the top, but that's not a rule, just a habit. Like I said before, as long as all the ground points are connected, the circuit will work. There are more advanced grounding techniques that can be used as well like star grounding, but I haven't had a need for them yet. BTW, I'm just a newbie too, so the standard disclaimers apply :wink:

[JazzBass]

Yeah, that's a 9VDC jack. You don't have to use one if you don't want to. You can just use a 9V battery if you don't feel comfortable having your first build plugged into the wall. As far as grounding in general is concened, all the ground points in a circuit are connected together. The sleeves of your input and output jack go to ground as well and -9V of the battery goes to the ring of the input jack (assuming it's a negative ground circuit). This is assuming you're just using a battery. If you're using a 9VDC jack and battery, the setup is a little different. If you're using a metal enclosure and switchcraft jacks, the enclosure will be grounded through the jacks, so you don't have to worry about running an additional wire from ground to the enclosure. Some people worry about a ground loop because of both jacks being connected to the enclosure; however, most people don't, and generally it's not a problem. If you want to get pedantic though, you can isolate one of the 1/4" jacks using a variety of methods, so that the enclosure is grounded at one and only one point. Here's a diagram showing a typical true bypass switch wiring scheme.

http://www.diystompboxes.com/beginner/circswled.jpg

I usually have all my ground points connected at the bottom of my perfboard and all my +9V connections at the top, but that's not a rule, just a habit. Like I said before, as long as all the ground points are connected, the circuit will work. There are more advanced grounding techniques that can be used as well like star grounding, but I haven't had a need for them yet. BTW, I'm just a newbie too, so the standard disclaimers apply :wink:

Thanks very much!  That makes pretty good sense and answered some questions.

Good info!

I appreciate it very much!  Nice to see another newbie around as well.

Take care,
JB