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OT - Grounding Question

OT - Grounding Question

2005-01-24 by Randy & Zonya Ledyard

Basic question about grounding here, couldn't find the answer on several
schematics I looked at, so I thought I'd ask it here, so the experts can set
me straight.

I putting together a power supply for my son, to power several of his guitar
effects boxes, and I had a question about grounding.

This is a basic transformer/diode bridge/7809 regulator with filter caps
circuit, running off 120 VAC (US)

Do I connect the ground from the 110 VAC to the ground on the DC side? If
it's in a metal case, should the case be grounded to the 110 VAC side also?

Re: [AVR-Chat] OT - Grounding Question

2005-01-24 by James Washer

I'm sure lots of folks will have lots to say about this... but let me just ask a question of you first.

When you say "ground from the 100 VAC" do you mean "ground" or "neutral". i.e. Are you using a 3-pronged-ground-lug plug, or the more conventional two-pronged plug, which has no ground, only hot and neutral, and which may or may not be polarized(, and which, even if polarized, may be plugged into an outlet with hot and neutral reversed)

 - jim

On Mon, 24 Jan 2005 00:55:45 -0500
"Randy & Zonya Ledyard" <rledyard@bigfoot.com> wrote:
Show quoted textHide quoted text
> Basic question about grounding here, couldn't find the answer on several
> schematics I looked at, so I thought I'd ask it here, so the experts can set
> me straight.
> 
> I putting together a power supply for my son, to power several of his guitar
> effects boxes, and I had a question about grounding.
> 
> This is a basic transformer/diode bridge/7809 regulator with filter caps
> circuit, running off 120 VAC (US)
> 
> Do I connect the ground from the 110 VAC to the ground on the DC side? If
> it's in a metal case, should the case be grounded to the 110 VAC side also?
> 
> 
> 
> 
> ------------------------------------------------
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RE: [AVR-Chat] OT - Grounding Question

2005-01-24 by Randy & Zonya Ledyard

James

I was referring to the "green" ground wire, not neutral - I'm planning on
using a 3-prong plug for the input - the hot and neutral run to the primary
on the transformer, but I'm confused about where the AC ground should go...

Should that AC ground be tied to the case and to the DC ground, or should
the DC ground be isolated from the AC ground?

Also, what about the shell of the transformer, should it be tied to AC
ground, DC ground, or both? This is for audio equipment (guitar effects) if
that makes any difference....

Randy
Show quoted textHide quoted text
> -----Original Message-----
> From: James Washer [mailto:washer@trlp.com]
> Sent: Monday, January 24, 2005 1:24 AM
> To: AVR-Chat@yahoogroups.com
> Subject: Re: [AVR-Chat] OT - Grounding Question
>
>
>
> I'm sure lots of folks will have lots to say about this... but
> let me just ask a question of you first.
>
> When you say "ground from the 100 VAC" do you mean "ground" or
> "neutral". i.e. Are you using a 3-pronged-ground-lug plug, or the
> more conventional two-pronged plug, which has no ground, only hot
> and neutral, and which may or may not be polarized(, and which,
> even if polarized, may be plugged into an outlet with hot and
> neutral reversed)
>
>  - jim
>
> On Mon, 24 Jan 2005 00:55:45 -0500
> "Randy & Zonya Ledyard" <rledyard@bigfoot.com> wrote:
>
> > Basic question about grounding here, couldn't find the answer on several
> > schematics I looked at, so I thought I'd ask it here, so the
> experts can set
> > me straight.
> >
> > I putting together a power supply for my son, to power several
> of his guitar
> > effects boxes, and I had a question about grounding.
> >
> > This is a basic transformer/diode bridge/7809 regulator with filter caps
> > circuit, running off 120 VAC (US)
> >
> > Do I connect the ground from the 110 VAC to the ground on the
> DC side? If
> > it's in a metal case, should the case be grounded to the 110
> VAC side also?

Re: [AVR-Chat] OT - Grounding Question

2005-01-24 by Roy E. Burrage

Randy,

That green wire is your ground.  All of your ground returns ought to be 
connected to it, as well as the transformer casing which would be 
automatic is you ground the case of your enclosure...assuming you're 
using a metal enclosure.

The white wire, neutral line, is also tied to ground (earth) but at 
either the breaker box or the transformer.  The green wire is always 
your earth ground, at least it's supposed to be.  Never connect your 
earth ground and neutral together at the equipment end of the power main.

You might also want to make sure you separate your analog circuit 
returns from your digital circuit returns (grounds) connecting them 
together only at one point on your circuit board.


REB



Randy & Zonya Ledyard wrote:
Show quoted textHide quoted text
>James
>
>I was referring to the "green" ground wire, not neutral - I'm planning on
>using a 3-prong plug for the input - the hot and neutral run to the primary
>on the transformer, but I'm confused about where the AC ground should go...
>
>Should that AC ground be tied to the case and to the DC ground, or should
>the DC ground be isolated from the AC ground?
>
>Also, what about the shell of the transformer, should it be tied to AC
>ground, DC ground, or both? This is for audio equipment (guitar effects) if
>that makes any difference....
>
>Randy
>
>  
>
>>-----Original Message-----
>>From: James Washer [mailto:washer@trlp.com]
>>Sent: Monday, January 24, 2005 1:24 AM
>>To: AVR-Chat@yahoogroups.com
>>Subject: Re: [AVR-Chat] OT - Grounding Question
>>
>>
>>
>>I'm sure lots of folks will have lots to say about this... but
>>let me just ask a question of you first.
>>
>>When you say "ground from the 100 VAC" do you mean "ground" or
>>"neutral". i.e. Are you using a 3-pronged-ground-lug plug, or the
>>more conventional two-pronged plug, which has no ground, only hot
>>and neutral, and which may or may not be polarized(, and which,
>>even if polarized, may be plugged into an outlet with hot and
>>neutral reversed)
>>
>> - jim
>>
>>On Mon, 24 Jan 2005 00:55:45 -0500
>>"Randy & Zonya Ledyard" <rledyard@bigfoot.com> wrote:
>>
>>    
>>
>>>Basic question about grounding here, couldn't find the answer on several
>>>schematics I looked at, so I thought I'd ask it here, so the
>>>      
>>>
>>experts can set
>>    
>>
>>>me straight.
>>>
>>>I putting together a power supply for my son, to power several
>>>      
>>>
>>of his guitar
>>    
>>
>>>effects boxes, and I had a question about grounding.
>>>
>>>This is a basic transformer/diode bridge/7809 regulator with filter caps
>>>circuit, running off 120 VAC (US)
>>>
>>>Do I connect the ground from the 110 VAC to the ground on the
>>>      
>>>
>>DC side? If
>>    
>>
>>>it's in a metal case, should the case be grounded to the 110
>>>      
>>>
>>VAC side also?
>>    
>>
>
>
>
>
> 
>Yahoo! Groups Links
>
>
>
> 
>
>
>
>
>
>  
>

Re: [AVR-Chat] OT - Grounding Question

2005-01-24 by Leon Heller

----- Original Message -----
Show quoted textHide quoted text
From: Randy & Zonya Ledyard
To: AVR-Chat@yahoogroups.com
Sent: Monday, January 24, 2005 8:25 AM
Subject: RE: [AVR-Chat] OT - Grounding Question


James

I was referring to the "green" ground wire, not neutral - I'm planning on
using a 3-prong plug for the input - the hot and neutral run to the primary
on the transformer, but I'm confused about where the AC ground should go...

Should that AC ground be tied to the case and to the DC ground, or should
the DC ground be isolated from the AC ground?

Also, what about the shell of the transformer, should it be tied to AC
ground, DC ground, or both? This is for audio equipment (guitar effects) if
that makes any difference....

I would connect AC mains earth/ground to DC ground and ground the 
transformer shell. There should be a suitable fuse in the connection to the 
AC mains line (hot). Apart from safety considerations, this should minimise 
mains hum and RF pickup. Get a transformer with an earth/ground screen, if 
possible. All UK supply sockets have an earth connection, and use a 
three-pin fused plug. "Double-insulated" equipment doesn't use the earth 
connection, of course.

Leon 



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RE: [AVR-Chat] OT - Grounding Question

2005-01-24 by Zack Widup

Yes, I always connect the center pin green ground lead to the metal case, 
along with the DC ground connections.

It's probably a good idea to ground the transformer case also, but 
sometimes not as easy to do and not necessary.  If you don't ahd have hum 
problems, then try it and see if it gets rid of the hum.

Zack
Show quoted textHide quoted text
On Mon, 24 Jan 2005, Randy & Zonya Ledyard wrote:

> James
> 
> I was referring to the "green" ground wire, not neutral - I'm planning on
> using a 3-prong plug for the input - the hot and neutral run to the
> primary
> on the transformer, but I'm confused about where the AC ground should
> go...
> 
> Should that AC ground be tied to the case and to the DC ground, or should
> the DC ground be isolated from the AC ground?
> 
> Also, what about the shell of the transformer, should it be tied to AC
> ground, DC ground, or both? This is for audio equipment (guitar effects)
> if
> that makes any difference....
> 
> Randy
>

Re: OT - Grounding Question

2005-01-24 by brewski922

On the AC side
Connect the High, hot, black wire to one wire of the transformer 
input.
Connect the Low, neutral, white wire to the other wire of the 
transformer input.
Connect the Ground, green wire to the metal cabinet. Mount the 
transformer to the metal cabinet. It would be best to use the same 
screw to mount the transformer and tie the Ground wire also. I would 
not connect the 120 VAC Ground to the Common of your DC power supply.
That takes care of the 120 VAC side.

The low voltage AC side:
Connect the output of the transformer through your bridge, or 
whatever, rectifier, filters and regulators. Now you should have a 
nice clean DC power source for your equipment completely isolated 
from the input side of the transformer. I would NOT connect the DC 
Common to the input AC Ground. Lots of times people talk about DC 
Ground when in fact it does not connect to Ground at all. It is 
Common, DC Common, to many places in the circuit but is never 
connected to Ground. These two electrical places exsist but neighter 
knows about the other except through the magnetic coupling of the 
transformer. Keep it that way.

Mike

--- In AVR-Chat@yahoogroups.com, "Randy & Zonya Ledyard" 
<rledyard@b...> wrote:
> Basic question about grounding here, couldn't find the answer on 
several
> schematics I looked at, so I thought I'd ask it here, so the 
experts can set
> me straight.
> 
> I putting together a power supply for my son, to power several of 
his guitar
> effects boxes, and I had a question about grounding.
> 
> This is a basic transformer/diode bridge/7809 regulator with filter 
caps
> circuit, running off 120 VAC (US)
> 
> Do I connect the ground from the 110 VAC to the ground on the DC 
side? If
> it's in a metal case, should the case be grounded to the 110 VAC 
side also?

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