Ideas for triggering a led wirelessly

Discussion in 'The Projects Forum' started by ekafrawy, Dec 18, 2007.

  1. ekafrawy

    Thread Starter New Member

    Apr 11, 2007
    6
    0
    I have a simple digital logic circuit using xor gates and a few inverters that basically triggers an attached LED to come on. What I am looking to do is somehow trigger an led wirelessy to come on when the output of my digital circuit is high. What could be used to do this correctly. the distance between the circuit and the LED would be a foot or two.

    Eric
     
  2. mrmeval

    Distinguished Member

    Jun 30, 2006
    833
    2
    Use an IR LED to send a high, use a phototransistor to receive it. You only really need the phototransistor, current limit resistor for the LED and the LED on the receiver and a DC voltage.

    The transmitter needs a high source and a current limit resistor for the IR LED if the digital output can source voltage. It has to be wired differently if it can only sink voltage.
     
  3. ekafrawy

    Thread Starter New Member

    Apr 11, 2007
    6
    0
    There is no line of site between the transmitter and the reciever, so I would need to use something else other than an IR transmitter. Anyone have any other ideas?
     
  4. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
    ekafrawy,

    A very cheap RF remote control can be created by modifying a micro RC car transmitter and receiver. Sometimes you can find these for less than $10US. The transmitter has 4 buttons: Forward-Back-Left-Right. These could be interfaced with your logic. The receiver has two open-collector outputs and an H-bridge (I think) output. 8 possible output combinations of single or double button presses are: F, B, L, R, F/L, F/R, B/L, B/R. I've used one for a remote control gag gift, and was able to get about 12 feet range with a longer wire on the receiver than the original car.

    Ken
     
  5. ekafrawy

    Thread Starter New Member

    Apr 11, 2007
    6
    0
    basically all i want is if the transmitter gets a High input signal(+5v) then the reciever should output the same high(+5V). Can i get a specific part# or website that could supply these? I thought this would be pretty staightforward.
    thanks
     
  6. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
    eric,

    I just posted a logic interface for a Radio Shack 49MHz ZIP-ZAP (not an SE model) car receiver on another thread:

    http://forum.allaboutcircuits.com/showthread.php?t=8515&page=2.....#14 post

    All you would need is the output circuit for the Left (R5, R9, R11, and Q4), and put your LED in series with R9.

    I haven't done anything with the transmitter, but the buttons just pull 3v logic lines to ground, so it could be done with a single transistor and a resistor to an external logic circuit.

    Ken
     
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