Ground Loop Isolation Help!!! Schematic or circuit needed....

anto777 · 18th December 2011, 06:34 AM

Hi i have built a basic amp with TDA2030 to drive my 2.1 speakers im able to hear humming noise when i connect it to my PC but the noise does not come when i connect it to my PC . I have double checked my wire connections and found it to be a Ground loop problem . Please advice me on the transformer to use and the circuit opto-isolators are preferred . thanks in advance

AndrewT · 18th December 2011, 12:03 PM

The noise is heard when you connect the PC.
The noise is not heard when you connect to the PC.
Which?

Tell us the whole story.

gk7 · 18th December 2011, 01:19 PM

Is your amp´s enclosure grounded (connected to mains earth, as it should be) ?
If so there most likely is a ground loop, because PCs are always connected to ground.

anto777 · 18th December 2011, 02:06 PM

Quote:

Originally Posted by AndrewT

The noise is heard when you connect the PC.
The noise is not heard when you connect to the PC.
Which?

Tell us the whole story.

Sorry andrew The noise is not heard when you connect to my PHONE

anto777 · 18th December 2011, 02:08 PM

Quote:

Originally Posted by gk7

Is your amp´s enclosure grounded (connected to mains earth, as it should be) ?
If so there most likely is a ground loop, because PCs are always connected to ground.

yeah my amp chassis is Grounded to earth

AndrewT · 18th December 2011, 02:23 PM

When the phone is on battery power, it is isolated from the mains.
There's your clue.

Now test your amplifier thoroughly before you attach any speaker.
When you are satisfied that the amp has passed all it's tests, start connecting your various source/s and test all combinations again, thoroughly.

Only when it has passed all these tests, do you attach a disposable (very cheap) speaker.

anto777 · 18th December 2011, 02:51 PM

Quote:

Originally Posted by AndrewT

When the phone is on battery power, it is isolated from the mains.
There's your clue.

Now test your amplifier thoroughly before you attach any speaker.
When you are satisfied that the amp has passed all it's tests, start connecting your various source/s and test all combinations again, thoroughly.

Only when it has passed all these tests, do you attach a disposable (very cheap) speaker.

well i attached the charger to my phone when i was playing music the noise came and when i disconnect it there was no noise
i found this 1:1 transformer and when i connect primary to pc audio out and secondary to the amp NO NOISE and NO BASS .

18th December 2011, 06:34 AM	#1
anto777 diyAudio Member Join Date: Aug 2010	Ground Loop Isolation Help!!! Schematic or circuit needed.... Hi i have built a basic amp with TDA2030 to drive my 2.1 speakers im able to hear humming noise when i connect it to my PC but the noise does not come when i connect it to my PC . I have double checked my wire connections and found it to be a Ground loop problem . Please advice me on the transformer to use and the circuit opto-isolators are preferred . thanks in advance

18th December 2011, 01:19 PM	#3
gk7 diyAudio Member Join Date: Oct 2007 Location: Vienna / Austria	Is your amp´s enclosure grounded (connected to mains earth, as it should be) ? If so there most likely is a ground loop, because PCs are always connected to ground. __________________ Regards, Georg

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18th December 2011, 12:03 PM	#2
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	The noise is heard when you connect the PC. The noise is not heard when you connect to the PC. Which? Tell us the whole story.

18th December 2011, 02:23 PM	#6
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	When the phone is on battery power, it is isolated from the mains. There's your clue. Now test your amplifier thoroughly before you attach any speaker. When you are satisfied that the amp has passed all it's tests, start connecting your various source/s and test all combinations again, thoroughly. Only when it has passed all these tests, do you attach a disposable (very cheap) speaker.