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need help selecting a transmitter and reciever

Discussion in 'Electronic Components' started by panfilero, Oct 21, 2008.

  1. panfilero

    panfilero Guest

    ok, basically I want to turn on and off an analog switch wirelessly.
    The range I need is very short... maybe around 20ft. And I need a
    transmitter as small as possible, and hopefully can run on a small
    battery (like a key fob and a watch battery). The transmitter only
    needs to be able to send 1 command to the reciever which would in turn
    tell my analog switch to open... I don't care how big the reciever
    is.... and this setup needs to be very responsive so that if someone
    taps the button on the transmitter side 10 times in 1 second, the
    reciever can open the switch 10 times in 1 second... very minimum
    delay, unpercitable... instant! I only want the switch to open while
    the button is pressed at all other times the switch should be
    closed....

    anyway, that's basically it.... can anyone make any suggestions or
    point me in the right direction as far as where I could find a
    reciever and a transmitter that would fit my criteria? I imagine...
    its a pretty simple/basic application... but I know nothing about
    reciever/transmitters....

    much thanks!
     
  2. Rich Grise

    Rich Grise Guest

    I once got a little tranmitter/receiver pair at Radio Shlock - the
    Xmtr was like a key fob, and the receiver was a plug-in box about
    the size of a coffee timer; that could be adapted.

    Good Luck!
    Rich
     
  3. http://www.futurlec.com/Radio.shtml

    These are very easy to use. Use a 4066, and drive it with the
    receiver.

    Regards,
    Bob Monsen
     
  4. cadcoke4

    cadcoke4 Guest

    If you are wanting something like a remote-control ventriloquist
    dummy, then you don't really need that kind of speed. But, regardless,
    you might get by with taking apart a remote-control toy car. Not the
    better kind with proportional control, but the really cheap kind that
    only has a few buttons. Then, you can cut the wires to the motors and
    use them for your control. But, you will need some electronics
    knowledge so that you stay within the current and voltages you have
    available need.

    Alternatively, is a source for a keyfob-style remote control kit.
    The link for the keyfob itself has listings for PDF's of the manuals,
    but the links aren't working. I have not used this, and have no idea
    if you can get the momentary output or speed that you need.
    http://www.kitsusa.net/phpstore/html/Remote-Control-Unit-Kits-35-1.html

    I've seen similar kits elsewhere.

    Joe Dunfee
     
  5. panfilero

    panfilero Guest

    Thanks for the Suggestion

    I don't know much (hardly anything) about this stuff.... some
    transmitter/reciever modules seem to come with encoder/decoder chips
    also.... are those required? I'm having a hard time finding just
    straight information on this stuff online.... just like.... reciever/
    tranciever basics... like... what's an encoder/decoder....

    I'm not going to control a ventriliquist thing... but what I want to
    be able to do is control an audio signal.... so when I push the
    button, then 10 feet away an audio signal will pass through my switch,
    but I have to be able to push the button and hear the audio at the
    same time.... which means I can afford some delay as long as its not
    perceptible to humans.... but I gotta be able to hit the button at
    least 10 times a second and get good tracking on that.... 10 times a
    second seems slow when talking about electronics, no?

    this kinda brings up another question that I was wondering about... if
    I'm using a switch like the 4066, and the audio signal swings into the
    negative... is that ok? The chip says it handles analog signals no
    problem... but I don't know if my signal (which is in millivolts)
    would pass through ok if it has a negative swing... which it does


    much thanks!
     
  6. panfilero

    panfilero Guest

    Thanks, do you know if I buy this... do I need to buy something called
    a encoder and decoder?
     
  7. panfilero

    panfilero Guest

    No but with two fingers I bet I could hit 20Hz
     
  8. The encoder chip will ensure that you are only getting signals from
    the sender, and not from some other stray 415MHz signal. If you don't
    really care about that, you can just use the output as is. I used one
    of these to run a servo once. No encoder, just the tx and rx pair, and
    it worked quite well.

    Regarding the 4066, you can't use it to switch signals outside the Vcc
    to Vss range. So, use a blocking capacitor, and then bias it into the
    middle of the range with two 100k resistors, one to Vss, one to Vcc.
    Then switch it. After this, use another cap to bring it back down to
    earth...

    Note that you can only switch signals with this arrangement. If you
    are trying to switch a speaker, it won't work well, since the 4066 has
    pretty high resistance when it is on. There are newer switches that
    have much lower resistance.

    Regards,
    Bob Monsen
     
  9. Glad to help. BTW, I like futurlec, but they are sloooow... you might
    be able to get these things at digikey or arrow, and have them ship in
    this century :)

    Regards,
    Bob Monsen
     
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