PCB design of parallel of two inverted LM3886 with buffer and dc-servo. - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

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 August 2006, 07:00 PM   #11
Roushon is offline Roushon  India
diyAudio Member
 
Join Date: Sep 2004
Location: Mumbai (Bombay)
Default sample

got as sample from National Semi.
__________________
S. Roushon
  Reply With Quote
Old 5th August 2006, 07:14 PM   #12
diyAudio Member
 
Join Date: Oct 2004
If you are still interested

This is the simplest way to parallel lm3886 chip. There is no servo, they are not needed.

Use one half of a dual op amp per channel. The value for the resistors is up to you, I use 4.2K.

Two pins of the trimmer are connected together and one pin is connected to ground.

Before connecting the outputs check, each chips dc. Turn the trimmers until dc is zero out or as close to zero as you can get it (usually around .1 to .3 mv). Now connect the outputs together
Attached Images
File Type: jpg parallel_lm3886.jpg (18.8 KB, 1524 views)
  Reply With Quote
Old 7th August 2006, 10:21 AM   #13
Roushon is offline Roushon  India
diyAudio Member
 
Join Date: Sep 2004
Location: Mumbai (Bombay)
Quote:
Originally posted by jaudio
If you are still interested

This is the simplest way to parallel lm3886 chip. There is no servo, they are not needed.

Use one half of a dual op amp per channel. The value for the resistors is up to you, I use 4.2K.

Two pins of the trimmer are connected together and one pin is connected to ground.

Before connecting the outputs check, each chips dc. Turn the trimmers until dc is zero out or as close to zero as you can get it (usually around .1 to .3 mv). Now connect the outputs together
Thanks a lot for your suggestion. But if the dc is made zero by this procedure, I do not know whether it will have some negative effect on the sound quality. I am curious because I have not seen this method before in any of the application notes of NS. There they always suggest to use a dc-servo when paralleling.
In any case I will try it also.
__________________
S. Roushon
  Reply With Quote
Old 7th August 2006, 10:53 AM   #14
diyAudio Member
 
Join Date: Oct 2004
Quote:
Originally posted by jaudio

The value for the resistors is up to you, I use 4.2K.
The value for the resistors is up to you, I use 4.2K4.2k and 57.7k resistors

Quote:
Originally posted by jaudio
Two pins of the trimmer are connected together and one pin is connected to ground.
.

Two pins of the trimmer are connected together , then connected to the (+) signal input and the third pin is connected to ground

I have not heard any negative effects
  Reply With Quote
Old 7th August 2006, 01:22 PM   #15
Roushon is offline Roushon  India
diyAudio Member
 
Join Date: Sep 2004
Location: Mumbai (Bombay)
I understood your description and the circuit before, did not need to repeat it. Thanks.
__________________
S. Roushon
  Reply With Quote
Old 16th August 2006, 07:48 PM   #16
Roushon is offline Roushon  India
diyAudio Member
 
Join Date: Sep 2004
Location: Mumbai (Bombay)
Default Hpfully final!!

Spent a lot of time for this revision of the pcb. Please give me your opinion. Tried to follow the application notes and some suggestions I received here. The pcb looks very complicated, but I hope it is a good design.
Attached Images
File Type: png lm3886-main-board.png (72.0 KB, 1437 views)
__________________
S. Roushon
  Reply With Quote
Old 16th August 2006, 07:56 PM   #17
Roushon is offline Roushon  India
diyAudio Member
 
Join Date: Sep 2004
Location: Mumbai (Bombay)
Default top

top of the pcb
Attached Images
File Type: png lm3886-main-board-top.png (25.2 KB, 1303 views)
__________________
S. Roushon
  Reply With Quote
Old 16th August 2006, 07:58 PM   #18
Roushon is offline Roushon  India
diyAudio Member
 
Join Date: Sep 2004
Location: Mumbai (Bombay)
Default bottom

bottom of the pcb
Attached Images
File Type: png lm3886-main-board-bottom.png (25.2 KB, 1265 views)
__________________
S. Roushon
  Reply With Quote
Old 17th August 2006, 04:54 AM   #19
Roushon is offline Roushon  India
diyAudio Member
 
Join Date: Sep 2004
Location: Mumbai (Bombay)
Default zobel

there are Zobels added in the pcb which are not there in the circuit diagram. also as I do not have enough low voltage 0.1uF, I had to use those fat ones (panasonic 0.1uF630v) that made the board a bit big. AD8620 is placed on the bottom of the board.
__________________
S. Roushon
  Reply With Quote
Old 17th August 2006, 03:23 PM   #20
Roushon is offline Roushon  India
diyAudio Member
 
Join Date: Sep 2004
Location: Mumbai (Bombay)
Default making the pcb

no comments so far...

regarding making the pcb I contacted some company here in mumbai. they need the order for at least 10 pcbs. I need only 2. would anybody like to join me for the pcb, if interested in the circuit? I am not trying to make a group buy, need to give away the remaining 8 and only within India. i do not know any other company who will make only 2 for me. if anybody has some information please share.....

thanks
__________________
S. Roushon
  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
LM3886, XO, Buffer and Servo jackinnj Chip Amps 3 30th October 2008 01:14 AM
Non inverted, 3 x parallel LM3886 schematics and layout. markiemrboo Chip Amps 0 6th December 2007 01:42 PM


New To Site? Need Help?

All times are GMT. The time now is 05:32 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