Somebody help me understand the principles behind this DC blocker? - Page 2 - 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 23rd September 2011, 04:53 AM   #11
diyAudio Member
 
Join Date: Jan 2004
Location: Toronto, ON, Canada
Quote:
Originally Posted by benb View Post
Yes, maybe - the AC voltage across the caps will be pretty small, as a SWAG maybe only 0.1V. Knowing the capacitance, one could calculate reactance at line frequency, and from that and the current pulled by the transformer calculate the voltage across the caps.
So that's what he's doing... the larger the capacitance, the lower the voltage drop?

But the caps will still see reversed voltage, right? I wonder how long they will last like that, even with low V.
  Reply With Quote
Old 26th September 2011, 03:10 AM   #12
expert in tautology
diyAudio Member
 
bear's Avatar
 
Join Date: Apr 2002
Location: New York State USA
use AC rated caps, avoid the problem?

it will just be larger and cost more...

_-_-

PS i think that current rather than voltage will be the bigger issue for electolytics...
__________________
_-_-bear
http://www.bearlabs.com -- Btw, I don't actually know anything, FYI -- [...2SJ74 Toshiba bogus asian parts - beware! ]
  Reply With Quote
Old 26th September 2011, 03:56 AM   #13
benb is offline benb  United States
diyAudio Member
 
Join Date: Apr 2010
Quote:
Originally Posted by 454Casull View Post
So that's what he's doing... the larger the capacitance, the lower the voltage drop?

But the caps will still see reversed voltage, right? I wonder how long they will last like that, even with low V.
Yes, they'll see reverse voltage. As he says or implies, electrolytics are apparently not "really" damaged as long as the reverse voltage stays below a volt or so. Worst case is they short out, and the transformer is connected directly to the line, which it would have been anyway without this circuit.

Apparently the biggest source of reverse voltage would be any DC offset on the line.
  Reply With Quote
Old 26th September 2011, 04:24 AM   #14
diyAudio Member
 
Join Date: Jan 2004
Location: Toronto, ON, Canada
nm

So is this worth doing for a linear supply?
  Reply With Quote
Old 26th September 2011, 05:35 AM   #15
benb is offline benb  United States
diyAudio Member
 
Join Date: Apr 2010
That calls for an opinion, and that's above my pay grade.
  Reply With Quote
Old 26th September 2011, 03:16 PM   #16
expert in tautology
diyAudio Member
 
bear's Avatar
 
Join Date: Apr 2002
Location: New York State USA
If ur transformers are humming, give it a shot...

_-_-bear

otherwise, ya know what else works?
an isolation transformer - it doesn't pass DC offset... fwiw.
__________________
_-_-bear
http://www.bearlabs.com -- Btw, I don't actually know anything, FYI -- [...2SJ74 Toshiba bogus asian parts - beware! ]
  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
DC blocker diode/cap orientation Glen B Solid State 4 22nd August 2011 06:46 PM
Help me understand DC servo FB. Artie Solid State 5 23rd June 2009 10:13 PM
I just installed Yeos (DIY Paradise) DC Blocker duderduderini Tubes / Valves 10 3rd October 2007 12:57 AM
dc blocker test report jeapel Pass Labs 5 4th July 2007 05:46 PM


New To Site? Need Help?

All times are GMT. The time now is 03:10 AM.


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