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Low power radio transmitter

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

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  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?

  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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