27 MHz Transmitter / Reciever

Discussion in 'General Electronics Chat' started by majmustache, Oct 31, 2013.

  1. majmustache

    Thread Starter New Member

    Oct 31, 2013
    3
    0
    Hey everyone,
    New to the forum so not sure what has been discussed already. I apologize for a repost. My question is:

    I want to build a transmitter and receiver pair which runs off of a 27 MHz L.O. capable of sending high/low (0 or 1) signal about 10 to 50 meters. I would like to do so using op-amps. I was thinking of using a push button to represent the 0 or 1 for now and then integrate a "trip wire" type of sensor in the future. My primary idea is to set this up in my office so I can tell when someone is coming through the door. Not for any malicious use but as a prank so I can always be prepared for any office tom foolery that might occur. Ideally this will be mobile and run off of batteries but for now it could be wired. So ultimately I am asking, where can I find a good schematic to work off of that uses op-amps to make a 27 MHz transmitter and receiver or can someone walk me through the steps of learning this.

    TL;DR: I want to build a 27 MHz transmitter receiver pair using op-amps and need help getting started / finding an applicable schematic to work from.
     
  2. panic mode

    Senior Member

    Oct 10, 2011
    1,321
    304
    if you get circuit that works the way you intended, would it bother you if it operated at some other frequency? 27MHz is used for CB.
     
  3. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
    1,066
    Opamps are not well suited for generating RF, nor for detecting it.
     
  4. KCHARROIS

    Member

    Jun 29, 2012
    292
    1
    If your looking for something quick, why dont you go to robotshop.com and by there 433 Tx-Rx modules? Its a quick and easy fix and its legal under a certain output power.
     
  5. PackratKing

    Well-Known Member

    Jul 13, 2008
    850
    215
    In your OP, you offered...

    " Not for any malicious use but as a prank so I can always be prepared for any office tom foolery that might occur "

    I Don't know where you are from, but where I work, office tom-foolery is a termination offense... zero tolerance.

    Too many people have been seriously hurt by morons thinking their stuff is funny.

    My major war story, is the teenager in the tractor dealership I worked with, that thought it was neat to use the Bernouli effect, to siphon the gasoline out of a pushmower tank, into a huge ignitable cloud - indoors - in the northeast winter... He could have blown the building off the map and killed us all, or seriously burned us all... I personally fired him on the spot, and the owner backed me up on it.
     
    Last edited: Nov 1, 2013
  6. majmustache

    Thread Starter New Member

    Oct 31, 2013
    3
    0
    Just nerf gun wars. Nothing that serious. Just something that allows us to lighten the mood on a dismal afternoon
     
  7. majmustache

    Thread Starter New Member

    Oct 31, 2013
    3
    0
    Panic Mode: I would prefer 27 MHz because of the distance it is capable of traveling but I am not set on it. I know it is CB and I figured if I kept it under a certain power I wouldn't interfere with radio operators.

    Mike ML: I was under the impression Op-amps were just transistors that were biased in a way that they were "ridden to the rails" and through their properties made them easier to work with as well as made it easier to eliminate some of the harmonics and provide sufficient gain even before putting it through an amplifier.

    KCHARROIS: I am interested in actually learning about these things rather than taking the easy way out with it. I do have other work to tend to so I rather not be spending more then a few months on this. Maybe have it done for Christmas?
     
  8. KCHARROIS

    Member

    Jun 29, 2012
    292
    1
    I used to be stuborn to, always wanted ti design everything from scratch and not use other prebuilt stuff. But as time went by I eventually tried prebuilt stuff and learned alot more that way. But think about it its to transmit, you still ned to be able to send out packets and decode those packets at the other end. Still some what a challenge after if you dont code microcontrollers very often. Its my opinion but up to you in the end.
     
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