FM transmitter using BA1404

Discussion in 'Wireless & RF Design' started by arunpradh, Jan 23, 2014.

  1. arunpradh

    Thread Starter Member

    Dec 11, 2013
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    which antenna is suitable for a short range fm transmission?.
     
    Last edited: Jun 12, 2014
  2. nedix

    New Member

    Jan 21, 2014
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  3. arunpradh

    Thread Starter Member

    Dec 11, 2013
    42
    3
    i want to make an fm transmitter with ba1404 as modulator.
    the 38 khz crystal is not avilable in the market.

    can i use 32.768 khz watch crystal insted of 38 khz?

    what is the role of this crystal? is this one is responsible for transmitting frequency?

    some body help me................
    :confused::confused::confused::confused::confused:
     
  4. crutschow

    Expert

    Mar 14, 2008
    13,016
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    You must use a 38kHz crystal. That's the frequency of the multiplexer for the stereo signal. If the transmitter frequency is not that value then the receiver cannot decode the stereo signal and the sound will be monophonic.
     
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  5. arunpradh

    Thread Starter Member

    Dec 11, 2013
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  6. alfacliff

    Well-Known Member

    Dec 13, 2013
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    between 88 and 108 mhz. its is an fm stereo transmitter. squeeze the coil or spread the turns to change the frequency.
     
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  7. wmodavis

    Well-Known Member

    Oct 23, 2010
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    Spec sheet says 76 to 108 mHz
     
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  8. MrChips

    Moderator

    Oct 2, 2009
    12,446
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    Google BA1404 FM transmitter.
    L1 is 3.5 turns on an adjustable ferrite core.
     
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  9. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    Think about the BH1417 chip instead. It is a later generation part with better sound, and uses a 7.6 MHz crystal to digitally synthesize the carrier and directly derive the 38 KHz pilot tone. I was going to build some, then found assembled circuits on ebay for about $5 each.

    If you really want to build from scratch, Mouser has the crystal for 50 cents.

    ak
     
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  10. arunpradh

    Thread Starter Member

    Dec 11, 2013
    42
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    can i use 2n2222 as an amplifier for higher power in addition to this chip ba 1404
     
  11. wmodavis

    Well-Known Member

    Oct 23, 2010
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    1. Yes you can use a 2N2222 as an amplifier.

    2. Maybe. But "higher power"? Higher than what? Are you asking about increasing the power output of the ba 1404? If so - how much power output does the ba 1404 have? What frequency are you talking about? What is the capability of the 2n2222 at that frequency?

    More questions than answers because you didn't clearly state what you really want or provide a schematic of what you have/want/propose so someone could provide a helpful answer without lots of guessing. I'm not a good guesser.
     
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  12. alfacliff

    Well-Known Member

    Dec 13, 2013
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    according to the spec on the ba1404, it has only 600 nanovolts coming out at 50kohm impedance. an amplifier could be built, but it would be a lot more complex than just a 2n2222.
     
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  13. bertus

    Administrator

    Apr 5, 2008
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  14. alfacliff

    Well-Known Member

    Dec 13, 2013
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    the spec sheet I was reading was a bit fuzzier. a 2n2222 would work for this chip, you would not even need to bias the chip, since fm does not need linear amplification like am or ssb.
     
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  15. arunpradh

    Thread Starter Member

    Dec 11, 2013
    42
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    i constructed the circuit of ba 1404 fm transmitter and it worked. i used 32.768 Khz crystal insted of 38 Khz. the circuit worked , i didnt checked the stereo separation. but it works. another fact is that when i removed the crystal the transmitter is still working.
    below is the schematics.
    http://www.electroschematics.com/wp-content/uploads/2009/09/ba1404-stereo-transmitter.jpg

    please some one help me to design an rf amp for it to increase its range.
    i saw a circuit which uses upc1675 as rf amplifier
     
  16. bertus

    Administrator

    Apr 5, 2008
    15,648
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    Hello,

    I have merged ALL 6 threads about your FM transmitter into one thread.
    You do NOT need to start a new thread for every question about the FM transmitter.
    The large number of threads will only create confusion.

    Bertus
     
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  17. arunpradh

    Thread Starter Member

    Dec 11, 2013
    42
    3
    i need suggestions for the selection of a transistor to make an rf amplifier for transmission of 90-99.9 Mhz (F.M).

    i also need the points to ponder while dealing with this .
     
  18. wmodavis

    Well-Known Member

    Oct 23, 2010
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  19. BR-549

    Well-Known Member

    Sep 22, 2013
    1,995
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    I am assuming because of the frequency range....this is a very low pwr amp. If this is true....you can buy very small boards with everything you need.......just attach 9 volt battery and mike.......for a couple of dollars. Search for mini fm transmitters. The older ones are discrete and you can experiment with them. The newer ones are just one IC.
     
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  20. alfacliff

    Well-Known Member

    Dec 13, 2013
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    if you want suguestions for an rf amplifier, you should give specifics, power output, and such. that will pretty much determine the transistor used.
     
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