unregulated wallmart power supply cap size - 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 18th June 2005, 07:33 PM   #1
ash_dac is offline ash_dac  United Kingdom
diyAudio Member
 
Join Date: Jan 2005
Location: UK
Question unregulated wallmart power supply cap size

Hi,


I opened up an unregulated ac wallwart for my QED Digit dac today. (The wallwart contains a transformer, 4 diodes, and 1000uf noname capacitor).

The wallwart is 12V dc (500mA).


Can I safely replace the 1000uf cap with a 100uf cap ?

(I have some 100uf 25V Black Gate capacitors )




Kind regards,


Ashley.
  Reply With Quote
Old 18th June 2005, 08:57 PM   #2
jaycee is offline jaycee  United Kingdom
diyAudio Member
 
Join Date: Apr 2004
Location: Norwich, UK
Sure you could, but you would be increasing ripple in the supply by reducing the rail capacitance. Better would be to add the Black Gates inside the DAC.
  Reply With Quote
Old 18th June 2005, 10:54 PM   #3
ash_dac is offline ash_dac  United Kingdom
diyAudio Member
 
Join Date: Jan 2005
Location: UK
Hi,


Thanks for the information.

I put two black gates inside the dac (I think one is for the regulator) and have been blown away by the change in sound .

Leave the 1000uf in there?

ps post title should have read walwart, and not wallmart


kind regards,


Ashley.
  Reply With Quote
Old 19th June 2005, 11:05 AM   #4
jaycee is offline jaycee  United Kingdom
diyAudio Member
 
Join Date: Apr 2004
Location: Norwich, UK
Yep. The capacitance that makes the difference is in the DAC... you won't really get any improvement by adding capacitance to the inside of the wallwart.
  Reply With Quote
Old 19th June 2005, 01:42 PM   #5
paulb is offline paulb  Canada
diyAudio Member
 
Join Date: Jun 2001
Location: Calgary
But it will probably sound worse without the 1000uF. No need to remove it.
  Reply With Quote
Old 16th August 2005, 07:56 PM   #6
ash_dac is offline ash_dac  United Kingdom
diyAudio Member
 
Join Date: Jan 2005
Location: UK
Hi,


I picked up some rubycon mbz caps off ebay. 1800uf

see:- http://www.rubycon.co.jp/en/catalog/...inum/e_MBZ.pdf


Is it a dangerous to put low esr caps after a rectifier bridge of a PSU?





Regards,


Ashley.
  Reply With Quote
Old 16th August 2005, 09:12 PM   #7
Stocker is offline Stocker  United States
diyAudio Member
 
Join Date: Dec 2003
Location: Austin
Not at 1800uF. Add a couple of zeros to that number and you have a short-circuit at the end of your rectifier string for a second or two after power-up. 1800uF I tend not to think twice about, unless the transformer is rated for single-digits of volt-amps.
__________________
Jesus loves you.
  Reply With Quote
Old 17th August 2005, 12:18 AM   #8
cerrem is offline cerrem  United States
diyAudio Member
 
Join Date: Jun 2005
Location: San Diego, CA
If it is an input cap after the bridge....then this won't do much since the SMPS flyback ciruit will adjust it's duty cycle for input voltage variation...
If the cap you are refering to is a output cap..then you should not deviate from it's original value, you run the risk of putting the SMPS into instability and oscilation... The output cap and Load resistance provide a POLE that is compensated by the error control loop....move the cap, then you may move the POLE and make problems...
Unless this thing is UNREGULATED?? :

Chris
  Reply With Quote
Old 17th August 2005, 02:21 AM   #9
Stocker is offline Stocker  United States
diyAudio Member
 
Join Date: Dec 2003
Location: Austin
Lightbulb Re: unregulated wallmart power supply cap size

Quote:
Originally posted by ash_dac
Hi,


I opened up an unregulated

Ashley.
please refer to the title of the thread.
__________________
Jesus loves you.
  Reply With Quote
Old 17th August 2005, 02:37 AM   #10
tade is offline tade  United States
diyAudio Member
 
Join Date: Feb 2005
Location: Ralieigh nc
Send a message via AIM to tade
We are snippy on this particular post aren't we?
  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
What size power supply should I get for repair work? spooney Car Audio 3 6th December 2007 11:50 PM
Using a dropping resistor in Zen V4 unregulated supply. G Pass Labs 3 30th October 2002 04:17 PM
Capacitor voltage rating for Zen V4 unregulated supply? G Pass Labs 2 24th October 2002 08:27 PM
Help with Zen v4 unregulated supply. G Pass Labs 2 23rd October 2002 02:10 PM
Increasing size of power supply caps. in BOZ. Yochim Pass Labs 1 9th September 2002 11:21 PM


New To Site? Need Help?

All times are GMT. The time now is 09:19 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