Sensor Used to Light up an LED

Discussion in 'The Projects Forum' started by jeff77789, Feb 22, 2013.

  1. jeff77789

    Thread Starter New Member

    Feb 22, 2013
    18
    0
    So you guys have to pardon my ignorance since i am new here...and new to general electronics as well but hopefully what i will say will make sense once you get to the end of it

    Basically, I have this sensor that takes a reading. This reading is a voltage and it can range from 0 mV to 2490.2 mV. This reading is going to be transferred wirelessly over 20ft to a receiver in which it interprets the data and acts as a switch to turn an LED on or off. The threshold voltage for this is going to be 1171.9 mV. When the voltage drops below 1171.9 mV, the light needs to turn on. (In the image, i wrote 2 volts but it is actually 1172 mV)

    The sensor/transmitter unit is powered by 14v DC and the receiver/LED unit is powered by 9v DC. There is actually 2 sensor units and 1 receiver unit. I plan on using RF links with different frequencies for the 2 Tx/Rx pairs to transfer data.


    [​IMG]

    What I circled in black is what I am having an issue with. I need components that will encode the analog output into something that the rf link can send (i also think that the AN output needs to be grounded but i am not sure about that)

    on the receiver side, i need something that can interpret the signal being transferred over, set a threshold of <1172 mV, and then act as a switch for the LED



    bonus:
    it would be nice if the LED's would start flashing if the voltage was <586 mV
    it would also be nice if the voltage threshold could be variable by a potentiometer

    ^those would be nice, but i guess that's out of my knowledge to implement

    thanks in advance everybody!
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,446
    3,362
    What are you using as the transmitter and the receiver?
    What you are asking for is easily done with a microcontroller.
    Is this option open to you?
    Do you know how to program and apply a microcontroller?
     
  3. jeff77789

    Thread Starter New Member

    Feb 22, 2013
    18
    0
    I plan on using a simple RF transmitter/receiver pair with two different frequencies:
    https://www.sparkfun.com/products/10532
    https://www.sparkfun.com/products/10534

    The option is open to me. the only thing preventing me from going that route is how to program and apply a microcontroller and how that will go along with the rest of the circuit
     
  4. MrChips

    Moderator

    Oct 2, 2009
    12,446
    3,362
    In order to use that transmitter/receiver pair to send digitally encoded information you will definitely need a pair of microcontrollers.

    You do not need to use two frequencies. Neither do you need two transmitter/receiver pairs. One will do.

    Have you used microcontrollers before?
     
  5. jeff77789

    Thread Starter New Member

    Feb 22, 2013
    18
    0
    no i have never used microcontrollers before

    i wrote X2 because I am actually going to be using 2 sensor units. therefore i will be sending information from 2 places to receive at one place. i said i needed 2 pairs at different frequencies so that these will not interfere with each other



    now, the sensor actually also has a "Tx" output in which it outputs:
    delivers
    asynchronous serial with an RS232 format, except voltages are 0-Vcc.
    The output is an ASCII capital “R”, followed by three ASCII character
    digits representing the range in inches up to a maximum of 255,
    followed by a carriage return (ASCII 13). The baud rate is 9600, 8
    bits, no parity, with one stop bit. Although the voltage of 0-Vcc is
    outside the RS232 standard, most RS232 devices have sufficient
    margin to read 0-Vcc serial data. If standard voltage level RS232 is
    desired, invert, and connect an RS232 converter such as a MAX232.
    When BW pin is held high the TX output sends a single pulse, suitable
    for low noise chaining. (no serial data).
    [this is an ultrasonic sensor]

    can this be connected directly to the RF transmitter?
    i think i would still need a microcontroller on the other end
     
    Last edited: Feb 22, 2013
Loading...