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How do I build this?

  1. Aug 18, 2011 #1
    Hello geeks of PF! Wooooo!

    I am in need of some help that will allow me to build a device.

    Roughly this is how I want my device to work -

    This device will help notify users about anything that I would like to notify them by indicating it through an LED. The device has got 2 ends; one end is attached to let's say a wall and the other is on the user like a wrist watch. Whenever the user enters an area (of let's say 100m) that has the first end installed then the end on the user will receive a signal and the LED will light up.

    Now please help me out here people.Websites have very bleak guidelines that can help me move ahead with my very first build. I am on the edge of destruction I have tried various means but to no avail. I have narrowed down to either using a transmitter/ receiver device or a radio-frequency identification device. If anyone of you has a better idea then please do let me know. PLEASE HELP ME BUILD THIS DEVICE THANKS =D

    It does not matter what signal I use or how I transmit the signal. What matters most is that the end product should have a feasible transmitting/receiving range of let's say 100m, consist of minimal number of interferences from other devices, portable and user-friendly. If we can get to this stage then later on maybe we have further improvise and innovate the product to a better finish.

    Attached is a brief sketch of how my device should work.

    Thanks mates,

    Attached Files:

    • IMG.pdf
      File size:
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    Last edited by a moderator: Aug 22, 2011
  2. jcsd
  3. Aug 22, 2011 #2


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    Staff: Mentor

    Welcome to the PF.

    A range of 100m would generally require you to use some licensed RF band. You might be able to use the ISM band (2.4GHz WiFi and microwave ovens), but the antenna will not be wristwatch size.

    What is the application? Perhaps we can suggest some alternatives. RFID is short range as well, BTW. On the order of a meter or few meters.
  4. Aug 22, 2011 #3
    Why not just use a PIR motion detector from a security system? Most of them have a relay output that can trigger all sorts of devices including LED's. I guess 100m would be pretty far for this sort of sensor as more motion detectors only work about 20 meters maximum.
  5. Aug 22, 2011 #4
    Cannot you use several sensors around the perimeter (like a light beam break detector) and hard wire the sensor to your Led Indicator?
    I am not getting the idea of wrist watch though!
  6. Sep 11, 2011 #5
    Well basically, the application for this device is to remind the user of putting on his safety gears whenever he enters a site that requires him to have safety gears on.
  7. Sep 12, 2011 #6
  8. Sep 13, 2011 #7
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