Results 1 to 5 of 5

Thread: Help needed for making an RF controller from scratch.

  1. #1

    Default Help needed for making an RF controller from scratch.

    Dear friends,
    I need to make a simplest possible 4 channel RF transreceiver circuit for controlling a robot, because the contest doesnot allow a readymade one. I have heard that the ICs Holtek 12D/12E decoder-encoder pair (more info on http://www.holtek.com/english/products/remote_1.htm) can be used for providing four way control for the robot on a single radio channel. But the output signal is only 38khz, which I think is PWM, perhaps good enough for IR remote. Can I connect it to some other IC so that it can modulate it to the RF range. If possible kindly tell the IC number and the price which could be work with minimal other circuit. Kindly also mention the IC number of the decoder of the encoder IC. The circuit I plan might look like :

    >-[HT12E]-38 khz-[Encoder IC])))xMhz))[Decoder IC]-38 khz-[HT12D]->

    ( I hope the ASCII diagram is not messed up )

    Anyway, Is Holtek's HT12D/12E available in Delhi. If possible kindly tell the price also. If not, kindly tell the alternatives to these ICs and their price.

    One more query. What are the frequencies in which we can legally operate our remote control upon in India?

    Thank you for reading such a long post.
    Yours sincerely,
    Kartik

  2. #2

    Default 4 channel rf

    hello,
    actualy what is your requirement? you said the output from the encoder and decoder is 38khz. but it is not , the 38khz is used to transfer the data only and it will not come out at the decoder output. the decoder output is 4-bit only. it is just like a ball and bat. if the ball is data , you need something to displace the ball from one place to another, so here bat is 38khz and the data's are ball. data's may be any thing but the transfer speed is at 38khz. the encoder and decoder areparallel to serial and serial to parallel output. coming to your need you can use ht 12e and 12d. at the input of the encoder set the bits as you need. say example:if it is 0001 means first channel, 0010- 2nd channel, 0011, 3rd channel,0100
    -4th channel. but you have to provide a demux and 'd' flipflop after the decoder to switch on/off independantly. it is advisable to use redymade rf module to transmit and receive.
    thanking you,
    g.krishnamurthy, ph:9382143429

  3. #3

    Default

    so, does that means that I can directly connect the output pin of the chip to the antennae?
    Thank you for your response.
    Kartik Joshi

  4. #4
    Super Moderator T-1000 docel's Avatar
    Join Date
    Sep 2005
    Location
    BANGALORE
    Posts
    1,441
    Blog Entries
    3

    Default rf

    hi dragonofages,
    Don't get confused. 12d/12E pair is for IR where 38Khz is the "carrier".
    This carrier is on/off modulated by the encoding BIT stream. This means that the 38KHz signal is switched on and off as a 12bit serial word.
    You cannot use this combo for RF switching.
    docel
    ^Anything is possible..
    after YOU prove it!!

    http://bangalorerobotics.tripod.com

  5. #5
    Super Moderator T-1000 docel's Avatar
    Join Date
    Sep 2005
    Location
    BANGALORE
    Posts
    1,441
    Blog Entries
    3

    Default Re: 4 channel rf

    Quote Originally Posted by krishneer
    hello,
    actualy what is your requirement? ... it is just like a ball and bat. if the ball is data , you need something to displace the ball from one place to another, so here bat is 38khz and the data's are ball. data's may be any thing but the transfer speed is at 38khz.

    -4th channel. but you have to provide a demux and 'd' flipflop after the decoder to switch on/off independantly. it is advisable to use redymade rf module to transmit and receive.
    thanking you,
    g.krishnamurthy, ph:9382143429
    While your contribution of help is welcome, please dont confuse the already confused minds! The above quote is very misguiding!!
    docel
    ^Anything is possible..
    after YOU prove it!!

    http://bangalorerobotics.tripod.com

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •