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rf morse code

Discussion in 'Electronic Basics' started by Andrey Fedorov, Aug 17, 2003.

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  1. I'm a high school senior and I've gotten into basic robotics lately. I'd
    like to build two circuits with PIC microcontrollers: one that sends an
    rf signal, and one that recieves it. I have learned the basic
    input/output of the PIC, but I'm having trouble figuring out how I can
    transmit information from one circuit to another (via rf).

    I'd like to make two circuits that can communicate (make a LED flash)
    via rf... A friend told me that I can use Quartz Crystals. Another said
    that's very unlikely, a third said that he's not sure, but it may be
    possible... does anyone have any suggestions, or better informational
    sources (web sites, tutorials?).

  2. happyhobit

    happyhobit Guest

    Hi Andrey,

    The simplest way to transmit info for a short distance (not outside) is
    Infrared. Use the PIC to modulate, turn on and off, an I/R LED at 40kHz. And
    use a 40kHz I/R detector receive it. OR, use your TV remote control to
    activate an I/R detector. (38kHz to 40kHz)

    I/R detectors; Vishay TSOP4840 and Panasonic PNA4613 (these are both 40kHz)

    Search Google for { "TV remote" 40kHz infrared }.

    A digital camera, still or video, can be used to see an infrared output.

    If you really want RF, search Google for { "RF transmitter" "low power"
    schematics }.

    Also try adding 'kits' in the Google searches for a quick start solution

  3. <snip>

    First and foremost: I have no idea which country you're in, but...
    most countries have some sort of government regulation concerning radio
    transmitters. When you build any such device, you need to be -really-
    careful about following the regs, either for low-power unlicensed
    devices or getting the appropriate license.

    It sounds to me, from your description, that getting your amateur
    ("ham") radio license would be a good first step. This will have the
    benefit of teaching you basic electronics and RF theory as well. Get
    that done first, and keep your project in the back of your head. The
    requirements to design and build it will become clear to you as your
    studies progress.

    Some first steps would include:

    * Visiting (gives you an
    introduction to the hobby, its purpose, and licensing requirements).

    * Picking up a copy of the 'Radio Amateur's Handbook,' published
    by ARRL. That should give you some education in RF and antenna design.

    * Use the club finder at to locate one that's local to
    you. Many clubs have training classes available to help you get your

    Good luck. It's a fun and rewarding hobby, and tinkering is one of
    the best parts about it.
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