Here's a design I'm working on... - 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 10th July 2006, 08:09 PM   #1
diyAudio Member
 
Join Date: Jun 2006
Default Here's a design I'm working on...

So, This is a "design" I'm thinking about trying. Not much unusual, but if anyone sees any glaring problems, let me know!
Attached Images
File Type: gif 50waudioamp.gif (14.7 KB, 568 views)
  Reply With Quote
Old 10th July 2006, 09:39 PM   #2
diyAudio Member
 
Join Date: Apr 2005
Location: In the Wild, Wild West
What is the purpose of R1 and R2? C1 and C2 at 680pF seems a little high to me but I don't think it will be a problem. Just seems smaller values are more common (I don't have any data comparing values to tell you an optimum value). Do you find that the L + R on the output are really necessary? For my amps I have never used those components, only the snubber on the ouput. Don't seen any problems. Surely your power supply will have much more capacitance than the 01.+ 10 + 1000 on the chips.

-SL
  Reply With Quote
Old 10th July 2006, 10:43 PM   #3
diyAudio Member
 
Join Date: Jun 2006
Yes, the PSU will have about 10000uF per rail, those rail caps you see in the schem are just "buffers".

R1, R2, the 680pF caps up through the "standard" 1uF DC bypass are all part of an input filter. I once saw someone use a similar design and I was intrigued, so I put it into PSPICE to see how it behaved. I decided on the 680 since it more agressively attenuates any high frequencies (above 100Khz). Of course, that shouldn't be coming in through the audio anyhow, but since I keep hearing about the instability of these chips in the HF range, I thought I'd try a little insurance.
  Reply With Quote
Old 11th July 2006, 12:04 AM   #4
jaycee is offline jaycee  United Kingdom
diyAudio Member
 
Join Date: Apr 2004
Location: Norwich, UK
All looks good to me, I've just built a similar circuit myself

http://www.darkmatter.myby.co.uk/pro...-schematic.png

As you can see I didn't bother with the capacitor on the MUTE pin. I found it unneccesary as I get no clicks at switch on without it, as the LM3886 includes supply monitoring that doesn't unmute the amp until the rails are >12V.

R7 on the diagram really has an inductor wound around it.

The capacitor between the + and - inputs is unneccesary if you have an ultrasonic filter on the inputs, provided your PCB is well laid out. You can also get away with no Zobel network, but if you really must have one, you can put it on the speaker output terminals instead of on your PCB.
  Reply With Quote
Old 11th July 2006, 02:48 PM   #5
diyAudio Member
 
Join Date: Jun 2006
Thanks for the info , Jaycee.

How do you handle the LR on the out? I mean, do you actually buy an inductor, or just wrap some wire around the output resistor? My DMM can do just about everything except inductance, so I worry a little bit about trying to wing it with a wire wrap. Who knows what L value I'd come up with.
  Reply With Quote
Old 11th July 2006, 04:23 PM   #6
jaycee is offline jaycee  United Kingdom
diyAudio Member
 
Join Date: Apr 2004
Location: Norwich, UK
I just wound the wire around the resistor. It's not actually that critical. If you buy, say, a 3W ceramic resistor and wind some enamelled wire around it, that's about right.

You can see the end result here:

http://www.darkmatter.myby.co.uk/pro...s/S2020016.JPG
  Reply With Quote
Old 11th July 2006, 04:29 PM   #7
diyAudio Member
 
darkfenriz's Avatar
 
Join Date: Jun 2004
Location: Warsaw
alitaido

C5 and C6 are intended for better stability?
Are you sure it works like this?
  Reply With Quote
Old 11th July 2006, 04:57 PM   #8
diyAudio Member
 
Join Date: Jun 2006
"C5 and C6 are intended for better stability?
Are you sure it works like this?"

in the case of these 220pF caps, I am taking the idea directly from the NS datasheet of the 3886.
  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
single-supply LM3875 design not working :( strykerhorse Chip Amps 4 30th May 2009 03:06 PM
WTB Krell KSA Mk2- working or non working Jozua Swap Meet 0 20th March 2006 11:14 AM
My Stereo Encoder Design not working -- PLS HELP..! xitronics Everything Else 11 28th May 2005 03:51 PM
Sub amp not working - please help! SimontY Solid State 7 24th May 2003 03:21 AM


New To Site? Need Help?

All times are GMT. The time now is 04:14 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