Gsm and RF rejection ... - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 12th October 2004, 10:00 AM   #1
djdamix is offline djdamix  France
diyAudio Member
 
Join Date: Jun 2004
Location: Lyon
Default Gsm and RF rejection ...

Hello,

I'm looking for a good solution to prevent RF and GSM detection with my amplifier, I now it could be done by filtering the input.
The input is a basic differential pair as on the following file :

http://www.diyaudio.com/forums/attac...&postid=488146

ps: there is no more DC offset ...


Any advice is welcome.

David
  Reply With Quote
Old 13th October 2004, 08:22 AM   #2
djdamix is offline djdamix  France
diyAudio Member
 
Join Date: Jun 2004
Location: Lyon
was it a stupid question ? is case of the amplifier supposed to stop all the RF ?

David
  Reply With Quote
Old 13th October 2004, 08:54 AM   #3
boholm is offline boholm  Denmark
diyAudio Member
 
boholm's Avatar
 
Join Date: Apr 2004
Location: Copenhagen
The problem is that RF can get in anywhere - not just on the input. Also the wires to the speaker are excellent antennas for RF. So if you have a problem with RF you can try the old trick, which is to do one winding round a ferrite core ring or using one of these: . . .wel . . . please do a search on Farnell using this search word "535886". Then you will get the picture

Ohterwise you can make an input filter. I recommend using 1 MHz as cutoff, so you will not interfere with the audio signal too much - fase and amplitude wise.
__________________
Best regards
Bo
  Reply With Quote
Old 13th October 2004, 08:56 AM   #4
Electrons are yellow and more is better!
diyAudio Member
 
peranders's Avatar
 
Join Date: Apr 2002
Location: Göteborg, Sweden
Blog Entries: 4
Good RF immunity comes also with a good pcb with groundplane but as a start and good decoupling and a LP-filter at the input.
__________________
/Per-Anders (my first name) or P-A as my friends call me
Super Regulator SSR03 Group buy. Still time for signing up.
  Reply With Quote
Old 13th October 2004, 09:01 AM   #5
djk is online now djk
diyAudio Member
 
djk's Avatar
 
Join Date: Feb 2001
Location: USA
You need to add R2 and C1 to your input stage:

http://users.ece.gatech.edu/~mleach/lowtim/instage.html

R2 - 2K

C1 - 390 pF mica (Arco DM15-391J or DigiKey 338-1057-ND

A ceramic cap may be used if nothing else is available.
  Reply With Quote
Old 13th October 2004, 09:11 AM   #6
djdamix is offline djdamix  France
diyAudio Member
 
Join Date: Jun 2004
Location: Lyon
thanks, I'll try that, I hope my GSM phone won't "sing" in the loudspeaker anymore.
  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
differential design, common mode noise rejection Sebastiaan Solid State 0 17th April 2006 08:16 PM
Ripple rejection caps - multiple? tonyptony Parts 4 23rd March 2006 06:58 PM
Power Supply Noise Rejection Ratio's (PSRR) Dr.H Digital Source 4 23rd July 2005 09:26 PM
Will AD1896 improve jitter rejection? yejun Digital Source 4 2nd July 2003 09:23 PM
Ultimate noise rejection annex666 Everything Else 2 29th July 2002 06:57 PM


New To Site? Need Help?

All times are GMT. The time now is 06:14 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