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BH1417 FM transmitter

Konusu 'Fm Verici Devreleri' forumundadır ve guclusat tarafından 29 Kasım 2010 başlatılmıştır.

  1. guclusat
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    guclusat Tanınmış Üye Süper Moderatör

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  2. guclusat
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    guclusat Tanınmış Üye Süper Moderatör

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    BH1417 Stereo PLL FM Transmitter

    BH1417_PLL_Stereo_FM_Transmitter.jpg

    [HR][/HR]
    [TABLE="width: 750, align: center"]
    [TR]
    [TD][TABLE="width: 458, align: center"]
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    [TD][TABLE="width: 458, align: center"]
    [TR]
    [TD]Parts:[/TD]
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    [TR]
    [TD][TABLE="width: 95%, align: center"]
    [TR]
    [TD][TABLE="width: 100%"]
    [TR]
    [TD]1x BH1417 - Stereo PLL Transmitter IC (Case SOP22)
    1x 7.6MHz Crystal
    1x MPSA13 - NPN Darlington Transistor
    1x 2.5 Turns Variable Coil
    1x MV2109 - Varicap Diode
    1x 4-DIP Switch
    ANT - 30 cm of copper wire

    1x 22K Resistor
    7x 10K Resistor
    1x 5.1K Resistor
    2x 3.3K Resistor
    1x 100 Ohm Resistor[/TD]
    [TD]1x 100uF Capacitor
    3x 10uF Capacitor
    2x 1uF Capacitor

    1x 47nF Capacitor
    3x 2.2nF Capacitor
    1x 1nF Capacitor
    1x 330pF Capacitor
    2x 150pF Capacitor
    1x 33pF Capacitor
    2x 27pF Capacitor
    1x 22pF Capacitor
    2x 10pF Capacitor[/TD]
    [/TR]
    [/TABLE]
    [/TD]
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    [/TD]
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    [/TD]
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    [/TD]
    [TD][TABLE="width: 255, align: center"]
    [TR]
    [TD][TABLE="width: 255, align: center"]
    [TR]
    [TD]Technical Specifications:[/TD]
    [/TR]
    [TR]
    [TD][TABLE="width: 90%, align: center"]
    [TR]
    [TD]Supply Voltage: 4 - 6V
    Transmission Frequency: 87.7 - 88.9MHz, 106.7 - 107.9MHz (200kHz steps)
    Output RF Power: 20mW
    Audio Frequency: 20 - 15KHz
    Separation: 40dB
    Power Consumption: 30mA

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    About BH1417 Stereo PLL FM Transmitter
    This is the latest BH1417 FM Transmitter design from RHOM that includes a lot of features in one small package. It comes with pre-emphasis, limiter so that the music can be transmitted at the same audio level, stereo encoder for stereo transmission, low pass filter that blocks any audio signals above 15KHz to prevent any RF interference, PLL circuit that provides rock solid frequency transmission (no more frequency drift), FM oscillator and RF output buffer.

    There are 14 possible transmission frequencies with 200KHz increments that users can select with a 4-DIP switch. Lower band frequencies start from 88.7 up to 89.9 MHz, and upper band frequencies start from 107.7 up to 108.9 MHz.

    BH1417 can be supplied with 4 - 6 voltage and consumes only around 30mA, providing 20mW output RF power. BH1417 provides 40dB channel separation which is pretty good, although older BA1404 FM Transmitter chip provides slightly better 45dB channel separation.

    BH1417 is only available in SOP22 IC case so this may be an inconvenience for some folks. On the other hand, because the chip is smaller than regular DIP-based ICs it is possible to fit the entire transmitter on a small PCB.

    BH1417 chip may also be used a stand alone stereo encoder. The advantage of that is that you have full freedom of using a transmitter & amplifier of your choice. You will still have a pre-emphasis, limiter, stereo encoder and low pass filter in one small package because very few external components are required for these blocks. PIN 5 is MPX output that can be directly connected to an external FM transmitter through a 10uF cap.


    BH1417 Block Diagram

    Main blocks of BH1417 chip are; pre-emphasis, (audio level) limiter, stereo encoder (MPX), PLL circuit, oscillator and RF buffer.


    BH1417_block_diagram.jpg
    Frequency Selection / Calibration[HR][/HR][TABLE="width: 100%"]
    [TR]
    [TD][/TD]
    [TD]Frequency selection is very straight forward. Simply select transmission frequency at which you would like to transmit, set the combination for 4-DIP switch and BH1417 will immediately tune to that frequency. If you can't hear the transmitted audio signal on your FM receiver then re-adjust 2.5 turn variable coil until you can hear the signal.
    As a test to see how PLL is working you can use a laboratory power supply to vary the voltage supply from 4 to 6V. While doing that BH1417 will automatically vary the voltage for MV2109 varicap diode making sure that there's no frequency drift.

    [TABLE="width: 400, align: center"]
    [TR]
    [TD]
    S1
    [/TD]
    [TD]
    S2
    [/TD]
    [TD]
    S3
    [/TD]
    [TD]
    S4
    [/TD]
    [TD]
    Frequency
    [/TD]
    [/TR]
    [TR]
    [TD]
    ON​
    [/TD]
    [TD]
    ON​
    [/TD]
    [TD]
    ON​
    [/TD]
    [TD]
    ON​
    [/TD]
    [TD]
    87.7 MHz​
    [/TD]
    [/TR]
    [TR]
    [TD]
    OFF​
    [/TD]
    [TD]
    ON​
    [/TD]
    [TD]
    ON​
    [/TD]
    [TD]
    ON​
    [/TD]
    [TD]
    87.9 MHz​
    [/TD]
    [/TR]
    [TR]
    [TD]
    ON​
    [/TD]
    [TD]
    OFF​
    [/TD]
    [TD]
    ON​
    [/TD]
    [TD]
    ON​
    [/TD]
    [TD]
    88.1 MHz​
    [/TD]
    [/TR]
    [TR]
    [TD]
    OFF​
    [/TD]
    [TD]
    OFF​
    [/TD]
    [TD]
    ON​
    [/TD]
    [TD]
    ON​
    [/TD]
    [TD]
    88.3 MHz​
    [/TD]
    [/TR]
    [TR]
    [TD]
    ON​
    [/TD]
    [TD]
    ON​
    [/TD]
    [TD]
    OFF​
    [/TD]
    [TD]
    ON​
    [/TD]
    [TD]
    88.5 MHz​
    [/TD]
    [/TR]
    [TR]
    [TD]
    OFF​
    [/TD]
    [TD]
    ON​
    [/TD]
    [TD]
    OFF​
    [/TD]
    [TD]
    ON​
    [/TD]
    [TD]
    88.7 MHz​
    [/TD]
    [/TR]
    [TR]
    [TD]
    ON​
    [/TD]
    [TD]
    OFF​
    [/TD]
    [TD]
    OFF​
    [/TD]
    [TD]
    ON​
    [/TD]
    [TD]
    88.9 MHz​
    [/TD]
    [/TR]
    [TR]
    [TD]
    ON​
    [/TD]
    [TD]
    ON​
    [/TD]
    [TD]
    ON​
    [/TD]
    [TD]
    OFF​
    [/TD]
    [TD]
    106.7MHz​
    [/TD]
    [/TR]
    [TR]
    [TD]
    OFF​
    [/TD]
    [TD]
    ON​
    [/TD]
    [TD]
    ON​
    [/TD]
    [TD]
    OFF​
    [/TD]
    [TD]
    106.9MHz​
    [/TD]
    [/TR]
    [TR]
    [TD]
    ON​
    [/TD]
    [TD]
    OFF​
    [/TD]
    [TD]
    ON​
    [/TD]
    [TD]
    OFF​
    [/TD]
    [TD]
    107.1MHz​
    [/TD]
    [/TR]
    [TR]
    [TD]
    OFF​
    [/TD]
    [TD]
    OFF​
    [/TD]
    [TD]
    ON​
    [/TD]
    [TD]
    OFF​
    [/TD]
    [TD]
    107.3MHz​
    [/TD]
    [/TR]
    [TR]
    [TD]
    ON​
    [/TD]
    [TD]
    ON​
    [/TD]
    [TD]
    OFF​
    [/TD]
    [TD]
    OFF​
    [/TD]
    [TD]
    107.5MHz​
    [/TD]
    [/TR]
    [TR]
    [TD]
    OFF​
    [/TD]
    [TD]
    ON​
    [/TD]
    [TD]
    OFF​
    [/TD]
    [TD]
    OFF​
    [/TD]
    [TD]
    107.7MHz​
    [/TD]
    [/TR]
    [TR]
    [TD]
    ON​
    [/TD]
    [TD]
    OFF​
    [/TD]
    [TD]
    OFF​
    [/TD]
    [TD]
    OFF​
    [/TD]
    [TD]
    107.9MHz​
    [/TD]
    [/TR]
    [/TABLE]



    [/TD]
    [/TR]
    [/TABLE]



    Frequently Asked Question[HR][/HR][TABLE="width: 816"]
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    [TD][/TD]
    [TD]
    This is list of answers to questions that I have received through an e-mail so far. If you should have any other questions please don't hesitate to e-mail them to me.

    What is the range of BH1417 Stereo FM Transmitter?
    Range of the transmitter depends on many factors.
    a) Length and type of the antenna (the longer the better, copper will radiate radio waves better than aluminum)
    b) Supplied voltage (6V Max power output)
    c) Weather conditions (clear skies & no humid, greater distance)
    d) Elevation above the ground (the higher the better)
    e) Line of sight (no buildings or trees, greater distance)
    f) Whether external amplifier is used

    I would like to be able to transmit the music to greater distances. Can you provide any suggestions on how to modify the circuit?
    You can connect an external amplifier based on the common 2N3866 / 2N4427 RF transistors. Please keep in mind that it is illegal to operate higher power transmitters in most of the countries without the proper license.
    [/TD]
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