Go Back   Home > Forums > General Interest > Everything Else

Everything Else Anything related to audio / video / electronics etc) BUT remember- we have many new forums where your thread may now fit! .... Parts, Equipment & Tools, Construction Tips, Software Tools......

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 15th August 2008, 09:44 AM   #1
diyAudio Member
 
Join Date: Aug 2008
Default Problem with hobbie FM Radio transmitter

Hello!

I've build a little FM radio transmitter to broadcast music around the appartment. It is powered by a 1,5V battery.
When I connect it to my MP3-player it sounds good, but when I connect it to my computer to broadcast iTunes I get a lot of buzz. It is like the signal is getting a lot weaker but it sounds good otherwise. So I just want to get rid of the noise.
Any suggestions?

thank you very much!
- Mattias
  Reply With Quote
Old 15th August 2008, 03:08 PM   #2
diyAudio Moderator Emeritus
 
Iain McNeill's Avatar
 
Join Date: Oct 2007
Location: Santa Cruz, California
My first guess would be RF interference from the PC upsetting your transmitter. Try moving the transmitter around or distance it with longer cord.

Can you post the schematic? Is it a chip based transmitter or discrete?
  Reply With Quote
Old 15th August 2008, 06:02 PM   #3
diyAudio Member
 
Join Date: Apr 2003
Location: Portland,Oregon
Blog Entries: 4
Send a message via AIM to DigitalJunkie
You can also try some small ferrite beads on the audio leads,and some small bypass caps,470pf or so.
I've noticed alot of HF 'hash" coming from PC soundcards,some simple filtering usually helps.
Putting your transmitter in a metal enclosure might be good also.
  Reply With Quote
Old 19th August 2008, 06:34 AM   #4
diyAudio Member
 
Join Date: Aug 2008
Thank you very much for your quick respons. I have not had the time to try out your solutions yet but I will.

here is the link to the schematic:

http://electronics-diy.com/BA1404_St...ransmitter.php

Mattias
  Reply With Quote
Old 19th August 2008, 05:51 PM   #5
diyAudio Moderator Emeritus
 
Iain McNeill's Avatar
 
Join Date: Oct 2007
Location: Santa Cruz, California
Hi,
I see some more problems:

-no ground plane
-unshielded L1 will pick up EMI and feed into modulator
-unfiltered antenna output

Putting this is a metal enclosure with ferrites on the I/O wires as DJ suggested will help considerably.

good luck
  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
Weird problem with DIT4192 SPDI/AES/EBU Transmitter Salar Digital Line Level 3 17th January 2009 08:09 AM
radio problem jeesus Solid State 1 1st August 2008 10:00 AM
Radio problem on noninverted GC??? 5150ed Chip Amps 2 17th August 2006 02:25 PM
My sub is a radio transmitter. mashaffer Subwoofers 6 7th April 2006 06:08 AM
Has anyone got a schematic for a 27Mhz Radio transmitter/reciever JBlissett Everything Else 0 3rd January 2006 12:19 PM


New To Site? Need Help?

All times are GMT. The time now is 12:02 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