+/- 28V 3A supply - 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 5th May 2010, 11:34 AM   #1
diyAudio Member
 
Join Date: Apr 2006
Location: up north
Default +/- 28V 3A supply

Could I make my supply for a 40W stereo powr amp running in class A like this drawing, with a "floating ground".
Attached Images
File Type: jpg 28V supply.jpg (31.3 KB, 380 views)
  Reply With Quote
Old 5th May 2010, 11:48 AM   #2
Mooly is online now Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
In theory yes... in practice it's perhaps not the best approach. If the amp has any points internally that connect to "ground" where a DC current flows or is sourced, then this will unbalance the "ground" with respect to the other rails.

Ultimately the "ground" is your chosen reference and an absolute, but it's what it does with the repect to the other rails that might be an issue

You could... use an NPN/PNP pair to make a sort of active ground, still with the large caps.

What's the amp anyway ?
__________________
-------------------------------------------------------
Installing and using LTspice. From beginner to advanced.
  Reply With Quote
Old 5th May 2010, 11:57 AM   #3
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Quote:
Originally Posted by andRookie View Post
40W stereo power amp running in class A
500VA and 40+40W of ClassA does not sound quite right. I think your 500VA will be run right at it's limit delivering this power.

Each channel will need ~ 1.6A of bias to give 40W of ClassA into 8r0.

Total bias for two channels is 3.2A continuous from the PSU.
__________________
regards Andrew T.
  Reply With Quote
Old 5th May 2010, 11:59 AM   #4
diyAudio Member
 
bobodioulasso's Avatar
 
Join Date: May 2008
Yes it works.
I used it for an F5.
The problem is , fo a class A amp, the total capacitor is divided by two. So tou have to add another big one across the vhole voltage.
Attached Images
File Type: jpg DSCN20611.JPG (37.5 KB, 362 views)
  Reply With Quote
Old 5th May 2010, 12:03 PM   #5
diyAudio Member
 
Join Date: Apr 2006
Location: up north
Quote:
Originally Posted by Mooly View Post
What's the amp anyway ?
It is an old gb150d module I bought second hand.
  Reply With Quote
Old 5th May 2010, 12:05 PM   #6
diyAudio Member
 
Join Date: Apr 2006
Location: up north
Quote:
Originally Posted by AndrewT View Post
I think your 500VA will be run right at it's limit delivering this power.
I actually have two of them. Just made the schem for simplicity.
  Reply With Quote
Old 5th May 2010, 12:06 PM   #7
Mooly is online now Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Quote:
Originally Posted by andRookie View Post
It is an old gb150d module I bought second hand.
Thank you... not familiar with it.
__________________
-------------------------------------------------------
Installing and using LTspice. From beginner to advanced.
  Reply With Quote
Old 5th May 2010, 12:23 PM   #8
diyAudio Member
 
Join Date: Apr 2006
Location: up north
Quote:
Originally Posted by Mooly View Post
You could... use an NPN/PNP pair to make a sort of active ground, still with the large caps.
What kind of transistors are suiteble for that "active ground" job?
  Reply With Quote
Old 5th May 2010, 12:37 PM   #9
diyAudio Member
 
bobodioulasso's Avatar
 
Join Date: May 2008
In the Quad 606, they use ztx652/ztx752
I used bd139/140, no heatsinks.
  Reply With Quote
Old 5th May 2010, 01:16 PM   #10
diyAudio Member
 
Join Date: Apr 2006
Location: up north
Ok, thanks.
IŽll try to make a schematic so maybe you guys can look through it.
  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
ISO Chip Amp to Use 28v-0-28v, 2A Toroid DreadPirate Chip Amps 1 14th November 2007 02:01 PM
12v Medical Grade Switching Supply 3.3A habsrock93 Swap Meet 2 27th April 2007 01:43 PM
if a power supply load is pulling 3A, does it means... jarthel Parts 8 24th April 2007 12:58 PM
regulated supply +- 28V -20A sss Power Supplies 8 14th June 2005 07:30 AM


New To Site? Need Help?

All times are GMT. The time now is 07:18 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