Help, FM Transmiter

Discussion in 'Wireless & RF Design' started by mrkabukiman, Dec 13, 2008.

  1. mrkabukiman

    Thread Starter New Member

    Dec 3, 2008
    Hi, I recently got into this whole circuitry "jive" and had gotten as far as constructing an fm transmitter. The thing of it is i'm not quite sure how to tune it to a specific radio frequency. I all honesty I havent the slightest of what I'm doing and would appreciate any help.

  2. beenthere

    Retired Moderator

    Apr 20, 2004
    Well, the FM band runs from 88 - 108 MHz. The usual procedure would be to tune a receiver to an empty part of the band and adjust L1 (while giving an audio input to one or both inputs) until you hear the transmitted signal.

    Using a non-metallic tool to adjust L1 will work much better. A metal tool will affect the tuning unpredictably.

    A BA1404 data sheet would give you some useful information.
  3. Audioguru


    Dec 20, 2007
    The lousy old BA1404 IC had poor performance so it was discontinued and replaced by a family of much better FM stereo transmitter ICs that use a crystal controlled frequency synthesizer with a phase-locked-loop.
    An Australian magazine Silicon Chip published The Micromitter project with one of the new ICs. Most inexpensive modern MP3 player to car radio FM stereo transmitters use one of the new ICs.

    The Indian site electronics-diy has two schematics using one of the new ICs: