LM3886 PCB -New DIyer - 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 11th December 2009, 03:37 AM   #1
yatgai is offline yatgai  India
diyAudio Member
 
Join Date: Sep 2006
Location: Goa India
Default LM3886 PCB -New DIyer

Hallow All

I am new DIYer and learned much from this forum. I am interested in making one LM3886 based chipamp to drive 8Ohm 3 way speakers they have own passive XO built in. My listening preference is Indian classical instrumentals at moderate volumes. For this purpose I feel 50 watt/ channel will be sufficient enough.

Set up in mind is
1. dual mono chip amps ( Non Inverted )
2. no preamp
3. 22k Ohm stereo pot at input
4. Audio source will be CD/VCD player

Amp Specifications are
1. transformer 24-0-24 Centre tapped, 300VA
2. 22k ohm linear pot at input
3. 1uF input capacitor
4. gain of 23 (1+R5/R3)
5. 2200uF capacitor (will they be too big?)

I have designed attached mono PCB in Eagle. Is this workable? Any suggestions / comments to improve ?

PS: I am not an engineer by training so many of the jargon is not understood

Thanks
Attached Images
File Type: gif PCB-3886.gif (32.1 KB, 451 views)
  Reply With Quote
Old 11th December 2009, 06:43 AM   #2
Dxvideo is offline Dxvideo  Turkey
diyAudio Member
 
Dxvideo's Avatar
 
Join Date: Nov 2003
Location: Turkey
Send a message via Yahoo to Dxvideo
It will work of course!
But;
You may want to use more thicker traces for V+, V- and speaker outputs, if you consider; the main current flow will trace on this ways.
22uF is not enough for feedback line, use 47u or higher to hear deep basses..
1uF is also not enough for input, I would use 4.7u for this position.
You can use 20K instead of 22K for all positions. Since you will use a CD player then you will have 2v RMS input level which is more than ebough for that gain.
And use curved corners for all the traces, electrons don't like cornered wires...
This may help you to make it better;
Attached Images
File Type: jpg 3886gcgc.JPG (85.0 KB, 427 views)
__________________
Best regards,
Ozgur
  Reply With Quote
Old 12th December 2009, 03:49 AM   #3
yatgai is offline yatgai  India
diyAudio Member
 
Join Date: Sep 2006
Location: Goa India
Default value of C1 capacitor

thanks dxvideo

i will impliment the changes as suggested.

one question though, changing the value of C1 capacitor from 1uF to 4.7uF will this kill the bass on the output ?

Thanks again
  Reply With Quote
Old 12th December 2009, 04:51 AM   #4
diyAudio Member
 
Join Date: Mar 2007
Dxvideo is right about the corners but not why. I suspect there is a translation problem and he means that 45 degree angles are industry standard. Electrons don't give a damn about having to go 90 degrees. Stick with 90's and 45's nothing in between.

Example of my horrible first try.
Click the image to open in full size.
  Reply With Quote
Old 12th December 2009, 06:44 AM   #5
diyAudio Member
 
Join Date: Dec 2009
It would work, the only thing is the
capacitor may stop working if the
current flow get deviated by any
means. Else everything is correct.

I must say not being an engineer you
did a wonderful job, No one can be
able to do this in such a perfect manner
without any technical support.
  Reply With Quote
Old 12th December 2009, 10:52 AM   #6
yatgai is offline yatgai  India
diyAudio Member
 
Join Date: Sep 2006
Location: Goa India
Default Current Diversion

Thanks lovejenete

"It would work, the only thing is the
capacitor may stop working if the
current flow get deviated by any
means"

> why would this happen, any precautions to be taken ? are the power traces too close? there is at least gap of 2mm between two traces.

"No one can be
able to do this in such a perfect manner
without any technical support."

> thanks for encouragement, yes in the begining I was helped by my engineer colleague, however soon later he changed the job, I suspect my pestering would have been one of the reasons.

Thanks again for your help
  Reply With Quote
Old 12th December 2009, 02:33 PM   #7
diyAudio Member
 
Join Date: Jan 2008
Quote:
Originally Posted by Rembrant View Post
Electrons don't give a damn about having to go 90 degrees. Stick with 90's and 45's nothing in between.
True at audio frequencies. Not true universally.

Also, I don't recall LM3886 being available in DIP-8

(Edit: Now that I've posted, it occurs to me that you probably mean your first try at PCB artwork generally)
  Reply With Quote
Old 14th December 2009, 02:51 AM   #8
Francec is offline Francec  Australia
Banned
 
Join Date: Jul 2006
Location: Port Melbourne, Australia
Quote:
Dxvideo is right about the corners but not why. I suspect there is a translation problem and he means that 45 degree angles are industry standard. Electrons don't give a damn about having to go 90 degrees. Stick with 90's and 45's nothing in between.
Electrons don't care about corners but etchant can become trapped under the etching mask and etch the inside corners of the traces.
Use 45 degrees wherever possible and round other corners if you can.
Frank
  Reply With Quote
Old 14th December 2009, 06:49 AM   #9
Dxvideo is offline Dxvideo  Turkey
diyAudio Member
 
Dxvideo's Avatar
 
Join Date: Nov 2003
Location: Turkey
Send a message via Yahoo to Dxvideo
Ok in fact I did not mean that exactly. But youre right, may be electrons dont care about the wires angle, however if you keep the traces 90 then electrons go more way compared to 45 traces. So that makes difference for electrons and for a final word, ELECTRONS DO CARE about the traces corners angles and dont like 90 corners.
Am I right?
__________________
Best regards,
Ozgur
  Reply With Quote
Old 14th December 2009, 08:20 AM   #10
diyAudio Member
 
Join Date: Oct 2009
As far from what I can remember from my EE EMC classes, electrons do care about corners up to some extent. It's not the longer trajectory, but at really high frequencies, sharp corners will cause more interference problems on your pcb. For audio frequencies this is not the case, but when you're doing stuff in the Mhz region, 45 degree angles are the way to go.
  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
Getting the DIYer blues again. Cassiel Tubes / Valves 23 5th December 2009 11:35 PM
Aussie DIYer. mattcalf Introductions 4 2nd May 2009 12:59 AM
For Aussie DIYer's Moondog55 Group Buys 21 19th October 2008 08:19 AM
My name is Hendrik and I am DIYer hendrikxix Introductions 3 15th May 2008 03:18 PM
New DIYer needs help. Tov Multi-Way 16 25th March 2004 02:59 AM


New To Site? Need Help?

All times are GMT. The time now is 06:13 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