Question about an FM Transmitter

Discussion in 'The Projects Forum' started by jdouglasusn, Aug 7, 2012.

  1. jdouglasusn

    Thread Starter New Member

    Aug 7, 2012
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    How exactly do we test this circuit to see if it's working properly?

    Do I plug in a audio device (let's say my MP3 player) to the audio input.
    Set my radio for like 103MHz, and adjust R1 until i hear something, or am I way off track?
     
  2. #12

    Expert

    Nov 30, 2010
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    That should tell you if the transmitter is working at all.
     
  3. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    I would do tht too.
     
  4. jdouglasusn

    Thread Starter New Member

    Aug 7, 2012
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    so i have the right idea then?
     
  5. #12

    Expert

    Nov 30, 2010
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    Two people just said you do.
    Are you waiting for the third opinion?
     
  6. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Yup...My ego wud do tht too.
     
  7. jdouglasusn

    Thread Starter New Member

    Aug 7, 2012
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    It didn't quite make sense. It seemed like it was the second part of a sentence, that is why I was asking to clarify.
    Any more snarky comments?
     
  8. #12

    Expert

    Nov 30, 2010
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    Wait as long as you want. It isn't going to bother us.
     
    Last edited: Aug 8, 2012
  9. wayneh

    Expert

    Sep 9, 2010
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    Since the circuit poses no risk to the MP3 player, I don't know why you're asking instead of just doing. Have you already tried the experiment and not gotten the results you hoped for?

    The only other approach would be to be far more cautious and assume your radio might blow up when you add power. The MP3 player is protected by the AC coupling capacitor, but the radio circuit is at risk. You COULD start by limiting current and slowly ramping it up until you're sure it's not drawing too much juice. Overly cautious, in my opinion, but appropriate if you have any doubts at all about your build.
     
  10. EarlAnderson

    Member

    Nov 13, 2011
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    Power up your circuit (without any audio source connected) tune your radio to the correct frequency, and adjust R1 until all static and background noise goes away, then your broadcasting and your circuit should be fine. If all is good, connect ur MP3 and play music. The coupling capacitor on the inputs will protect ur MP3 from any DC voltage, preventing any damage.
     
  11. BillB3857

    Senior Member

    Feb 28, 2009
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  12. jdouglasusn

    Thread Starter New Member

    Aug 7, 2012
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    Thanks anyways, that is all over google.

    I solved the issue. My radio had a crappy antenna, or just a crappy radio. It just wouldn't pick up my transmitter signal for some reason.

    A work the radio I used can get it from across the room clear as crystal. Thanks for any help you offered though :)
     
  13. jdouglasusn

    Thread Starter New Member

    Aug 7, 2012
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    0
    If you must know, I was at work and didn't have anythingon me, so I thought I might do a forum troubleshooting and get some ideas.

    I also wasn't worried about blowing up anything, it was just a simple question.

    Either way the receiving radio was messed up, that is why everything wasn't great. Swapped the radio and everything worked fine. Thanks for any help though.
     
  14. #12

    Expert

    Nov 30, 2010
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    You're welcome.
     
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