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Low power radio transmitter

Discussion in 'Hobby Electronics' started by Craig Welch, Dec 23, 2005.

  1. Craig Welch

    Craig Welch Guest

    If this is the wrong group for this question, I'm sure you will all
    tell me to sod off, so ...

    My mail box is a few hundred yards from the house. I'd like to put a
    micro switch in the box, and switch on a low power (milliwatts)
    transmitter to activate a receiver and LED in the house.

    Anyone have any good ideas? Can email me a circuit or point me to
    one on the web?

    Thanks,
     
  2. By far the easiest way is to use an optical transmitter (narrow angle
    super-bright LED) and use your eye as a receiver. Add a flasher
    circuit that powers it for a tenth of a second every two seconds,
    and the batteries will last years.
     
  3. Craig Welch

    Craig Welch Guest

    Thanks, but the mailbox is not visible from the house. Long, curved
    tree-lined driveway.
     
  4. Phil Allison

    Phil Allison Guest

    "Craig Welch"
    ** Idea:

    Buy two cheap UHF CB radios - circa $65 a pair.

    Use the micro-switch on the letter flap to trigger a timer to power up the
    CB in the mail box for a few seconds so it can send a call tone to the one
    in the house. This will save massively on battery life.

    The one in the house is powered from an adaptor an left on 24/7.

    Additional idea:

    Have the timer re-send a call tone each 15 minutes until manually re-set by
    someone at the box.



    .......... Phil
     
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