power supply ground floating

yardcat

Joined Nov 27, 2008
4
Maybe this is a novice question but I haven't found an answer. I want to put several guitar effects circuits chained together in one enclosure. Some circuits are plain 9 volt and some are dual supply +9 and -9 volts.

My question is, if I use a line operated dual power supply from a CT transformer will I run into trouble with the ground? It seems to me that I will burn out half of the transformer. It is my understanding that a dual supply has a floating ground and the guitar amp's ground, which is connected by the guitar cable is connected to earth ground. Is my understanding right? what should I do?

Thanks, from someone with a very little knowledge.
yardcat

leftyretro

Joined Nov 25, 2008
395
Maybe this is a novice question but I haven't found an answer. I want to put several guitar effects circuits chained together in one enclosure. Some circuits are plain 9 volt and some are dual supply +9 and -9 volts.

My question is, if I use a line operated dual power supply from a CT transformer will I run into trouble with the ground? It seems to me that I will burn out half of the transformer. It is my understanding that a dual supply has a floating ground and the guitar amp's ground, which is connected by the guitar cable is connected to earth ground. Is my understanding right? what should I do?

Thanks, from someone with a very little knowledge.
yardcat
As long as your dual supply is using a tranformer with a center tapped secondary winding it's OK to connect the center tap to ground and connect it to any other circuit ground.

Lefty

Wendy

Joined Mar 24, 2008
23,140
There is no problem if one side of the transformer is loaded more than the other, as long as the current on the more loaded side isn't exceeded. It is standard practice.

yardcat

Joined Nov 27, 2008
4
As long as your dual supply is using a tranformer with a center tapped secondary winding it's OK to connect the center tap to ground and connect it to any other circuit ground.

Lefty
So, I can safely connect the center tapped ground to earth ground? If I turn on the power I read an AC voltage of 19 volts between the CT ground and the earth ground of the wall socket. This confuses me.
yardcat

leftyretro

Joined Nov 25, 2008
395
So, I can safely connect the center tapped ground to earth ground? If I turn on the power I read an AC voltage of 19 volts between the CT ground and the earth ground of the wall socket. This confuses me.
yardcat
Yes, you can wire them together if you wish. You don't have to do that and if not your supply would be said to be 'floating' in respect to your home power wiring ground. Circuit common and true ground are two different things, however if wired together your circuit ground then becomes a true ground. It depends on what you are doing and the voltage levels being generated in your power supply, if it's advantageous to wire to AC ground or not.