DC noise come from live or neutral? - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 15th January 2011, 03:02 PM   #1
diyAudio Member
 
Join Date: Dec 2010
Location: Pearl of Orient
Default DC noise come from live or neutral?

Normally DC noise injected through live, neutral or both?
  Reply With Quote
Old 15th January 2011, 03:56 PM   #2
Did it Himself
diyAudio Member
 
richie00boy's Avatar
 
Join Date: Nov 2003
Location: Gloucestershire, England, UK
Both, current flows in a loop through live and neutral and can be in either direction.
__________________
www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more.
  Reply With Quote
Old 15th January 2011, 04:02 PM   #3
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
Neither? DC is not noise, although both are unwanted in a mains supply.

DC, if present, must involve both conductors as richie00boy says.

Noise may come on both or just one, so mains filters handle common-mode and differential-mode noise.
  Reply With Quote
Old 15th January 2011, 04:10 PM   #4
diyAudio Member
 
Join Date: Dec 2010
Location: Pearl of Orient
my speakers producing the same buzzing sound as transformer when DC present.

good high current DC blocker too expensive to DIY.
  Reply With Quote
Old 15th January 2011, 04:25 PM   #5
diyAudio Member
 
Join Date: Sep 2004
Location: Minneapolis, Minnesota, USA
Are you sure you have a problem with DC on your mains? That usually causes the trasformer itself to buzz, not through the speakers. Buzzing from your speakers is more likely to be caused by a ground loop or possibly a bad ground connection between components in the system. If you do have a DC problem, it's not that difficult or expensive to fix it, check out Rod Elliot,s site or do a search right here, lots of good info.
  Reply With Quote
Old 15th January 2011, 04:55 PM   #6
diyAudio Member
 
Join Date: Dec 2010
Location: Pearl of Orient
My transformer buzz itself for sometimes(don't know what is the source of DC) and on water heater confirm will cause it to buzz. my speaker only buzz when the transformer buzz, put my ear 3-5cm near to speaker only can hear it.

Yes. I found a lot of DC blockers. This is the one I trusted.
Mains DC and Transformers
most of the high current application DC blocker required high capacitance capacitor equal to high cost and Rod Elliot,s required high inductance, which is very costly isn't it?
I have two audio system here, my pc(750watts)+LM3886(225watts) and hometheater 1000-1500watts.

is there any alternative way to do to the mains instead of DC blocker?
  Reply With Quote
Old 15th January 2011, 05:26 PM   #7
Electrons are yellow and more is better!
diyAudio Member
 
peranders's Avatar
 
Join Date: Apr 2002
Location: Göteborg, Sweden
Blog Entries: 4
I think you have misunderstood Rod's article. You can never get away with other than high capacitance caps. The inductance circuit Rod has drawn is the equivalent circuit for a transformer.

My solution looks like this.
__________________
/Per-Anders (my first name) or P-A as my friends call me
  Reply With Quote
Old 15th January 2011, 06:00 PM   #8
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
If DC is the problem then only a DC blocker is the solution.

If noise is the problem then a mains filter should help.
  Reply With Quote
Old 15th January 2011, 11:45 PM   #9
diyAudio Member
 
zigzagflux's Avatar
 
Join Date: Oct 2006
Location: Charlotte, NC
DC is extremely rare, and often misdiagnosed. The presence of 120Hz will make a meter read some DC residual; I can measure this on the secondary of my power transformer (definitely no DC getting through there) but the meter says there is DC present. It can be ignored, and is likely not the source of noise you are describing.

DC should not be present in a power system unless there is equipment connected that does not belong, or a system that is lacking. A DC blocker is a band aid to a larger problem.

You say the noise increases when your water heater turns on ?
  Reply With Quote
Old 16th January 2011, 03:07 AM   #10
diyAudio Member
 
Join Date: Dec 2010
Location: Pearl of Orient
@zigzag
most of the time I can't hear any little buzz from the trans.
the noise occur when heater turns on. some one told me before that the heater injecting harmonic 120hz, 180hz, 240hz, 300hz or...into the line.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Low noise DC regulator problem mravlca Power Supplies 14 3rd February 2010 03:27 PM
Where Can I Pick Up Neutral jobsworth` Tubes / Valves 3 1st September 2008 03:42 AM
How to remove noise from DC line? tripathdude Digital Source 1 20th March 2008 05:26 PM
DC motor and supplies (Origin Live) mallen Analogue Source 1 10th May 2005 12:42 PM
DC heater noise WORSE than AC arnoldc Tubes / Valves 13 12th October 2004 02:23 AM


New To Site? Need Help?

All times are GMT. The time now is 01:05 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2