what do you think about my LM3886 PCB design? - 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 4th October 2012, 12:46 PM   #1
diyAudio Member
 
Join Date: May 2010
Wink what do you think about my LM3886 PCB design?

Hi! this is my design, its not final, i guess the real thing would be a little more aesthetic, but it shows the idea.

- the supply caps on the board will be changed to 220uF
- i know the V- cap is far from the chip but i thought it would be better to sacrifice it for good grounding.
- the speaker ground won't be connected from this board, it will be connected from the star ground of the case, this trace is an optional connection, do you think it may cause a problem?
- 0.1 caps will be soldered directly at the suply pins and will be connected to the pin 7 (ground pin of the IC), is it ok?

Click the image to open in full size.

tnks guys
  Reply With Quote
Old 4th October 2012, 05:37 PM   #2
Boscoe is offline Boscoe  United Kingdom
diyAudio Member
 
Join Date: Feb 2010
Location: England
There's no pic...
__________________
I thought about it once, but then thought again.
  Reply With Quote
Old 4th October 2012, 05:51 PM   #3
diyAudio Member
 
yagoolar's Avatar
 
Join Date: Oct 2004
Location: Mazowieckie, Jozefoslaw
Send a message via ICQ to yagoolar Send a message via Skype™ to yagoolar
Quote:
Originally Posted by Boscoe View Post
There's no pic...
There is. I can see.
  Reply With Quote
Old 4th October 2012, 05:53 PM   #4
Boscoe is offline Boscoe  United Kingdom
diyAudio Member
 
Join Date: Feb 2010
Location: England
I can see it now.

The layout looks okay but you could get that coupling cap closer to the chip just out it in the other side of the other cap and join their GNDs together with a link to GND - I'm sure the LM won't mind!

Why do you have a 10r output resistor? You should connect your speaker GND to the board then connect the board to PSU GND. The PSU connection to chassis (if you choose to use one) should be a branch off the PSU star GND.
__________________
I thought about it once, but then thought again.

Last edited by Boscoe; 4th October 2012 at 05:59 PM.
  Reply With Quote
Old 4th October 2012, 08:16 PM   #5
diyAudio Member
 
Join Date: May 2010
Tnks Boscoe! You realy opened my eyes! I can't think of a way to ground this cap if it will be where you ment (if i figured right its above the CS2),
But your comment made me think of another way to get it closer, to lower the ground trace to the connector, and make another tarce of V- (for the cap) from between the connector's V+ and ground pins.
But I would be happy if you'll try to explain me your suggestion, it may be way better.

The 10R resistor will be paralleled to an indactor, if i won't find a nice choke it will be a magnet wire wraped around the resistor.

About the grounding for the speakers, I saw on the web several ways to do it, but the way that convinced me the most was to run the PSU ground to a star on the case and from their run it to the boards and to the speakers directly.
I don't know what way is the best so i left the option you said and i will check what's best.

And another thing, I cant decide what resistor to use for the zobel (RSN) 2.7R or 10R.
  Reply With Quote
Old 5th October 2012, 06:48 AM   #6
Boscoe is offline Boscoe  United Kingdom
diyAudio Member
 
Join Date: Feb 2010
Location: England
Work out the roll off of the filter and see what you think. Regarding the output inductor/resistor, leave the possibility to add it later, I have built quite a few LM3886/3875 without the zobel even so you might get away without it but this needs to be decided once its built and tested. However it might be fine with one setup and unstable with another depending on the cable and speaker load/crossover.
__________________
I thought about it once, but then thought again.
  Reply With Quote
Old 5th October 2012, 12:58 PM   #7
diyAudio Member
 
Join Date: May 2010
Tnks Boscoe, I prefer the amp to be stable for every setup so I will keep the zobel.
I will always have the posibility to wire the output to the connector directly (without the zobel).

So here is what i did, very messy but only to present the idea:

Click the image to open in full size.

you think it is better like this? maybe i should use your idea (witch i didn't understand yet)?
  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
PCB design of parallel of two inverted LM3886 with buffer and dc-servo. Roushon Chip Amps 74 11th April 2012 11:17 AM
LM3886 on 1sided PCB design random007 Chip Amps 73 12th November 2010 05:50 AM
LM3886 stereo - PCB design Razor_x Chip Amps 2 3rd July 2009 12:18 PM
lm3886 PCB 13814044 Chip Amps 20 25th October 2008 04:09 PM


New To Site? Need Help?

All times are GMT. The time now is 08:23 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