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modulation in R/c cars.....

Discussion in 'Wireless & RF Design' started by ispeak, Mar 20, 2008.

  1. ispeak

    Thread Starter New Member

    Mar 17, 2008
    hai... people
    we are making a spy robot which is our final year project which is a prototype of military spying robot.
    the questions are as follows

    1. we are using a transmitter and recevier circuit which is taken from remote control toy car we want to know what will be the modulation of it?? whether it is AM/FM??the ic in the circuit is TXRX-2B...

    2. what is the maximum ferequency and range in wireless transmittion??
    please reply... waiting for the reply fast....
  2. mrmeval

    AAC Fanatic!

    Jun 30, 2006
    Offering gold makes fast, slow is free.
  3. rwmoekoe

    Active Member

    Mar 1, 2007
    1. the common practice is that people use fm modulation. the ic wouldn't be critical, it could be of many kinds.
    2. usually the frequencies are 27mhz and 72mhz. there may be other frequencies as well.
    the range is usually under 5km radius at best, but it depends on the signal strength of the transmitter.
  4. jpanhalt


    Jan 18, 2008
    Remote toy cars in the US are usually on 27 or 75 MHz. The 72 MHz band is for aircraft. Some countries and areas, such as the EU and England, use different frequency assignments.

    As for modulation, FM is most common for mid to high end, which are also almost all 75 MHz (for cars). At the low price end, one still finds AM. The 27 MHz units are usually at the least expensive end, and a lot of 27 MHz stuff is on AM. Some is even super-regenerative, not superhet. The range is low and selectivity is poor for most of the 27 MHz units with which I am familiar.

  5. beenthere

    Retired Moderator

    Apr 20, 2004
    There used to be some R/C stuff running at 49 MHz. For servos, it's a kind of PWM.
  6. thingmaker3

    Retired Moderator

    May 16, 2005
    I'm going repeat my query from the last time you asked about this: What is the manufacturer and model of the toy car you pulled the circuit from?
  7. NM2008

    Senior Member

    Feb 9, 2008
    From my experience of R/C equipment, I find that transmitters for radio controlled toy cars tend to be dodgy. Over time they become somewhat unreliable, as in a drastic drop in range and response time in comparison to when first used.
    When you say toy car, I presume it is lower end/cheaper model, In this case, with regard to range you would be lucky to get 50metres.

    For small projects there are many reliable transmitter/receiver units out there, for example Futaba and Hitech have some reasonably priced starter kits, which can be picked up on Ebay.

    At least that way you will know what you are dealing with for definite.

  8. scubasteve_911

    AAC Fanatic!

    Dec 27, 2007
    NM2008 is right on with his advice. Don't overcomplicate your project, you will definitely run into many unexpected and more application-specific problems as you move along, which you should expect ahead of time by making things as simple as possible.