Switch mod.

Discussion in 'The Projects Forum' started by ecjohnny, Oct 15, 2008.

  1. ecjohnny

    Thread Starter Senior Member

    Jul 16, 2005
    142
    0
    Thanks for the repeater mod help from my other thread.

    Here is a new challenging task given by me. i am using a hanger (like a hook) to hang a key.

    How can i make switch or any solutions that i can achieve below procedure:

    1) a key hanging to the hook will open the circuit.

    2)When anyone remove the key, it will closed circuit(complete circuit) and my
    transmitter will be activated.

    3) here is what i am stuck with since i have closed the switch, the transmitter will keep on transmitting thereby wasting power UNTIL i return the key. how can i open up the circuit again WITHOUT hanging back the key.

    4) Key returns and it STILL a open circuit and back to step 1.

    Any method/ solution are welcome. If your answer is a pressure switch, please explain me how it works. i have never use it before.

    Thanks a lot.
     
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    You can use a small limit switch on the hook to sense that the key has been removed and then use a timer (may a 555) to switch off the transmitter after a while.
     
  3. ecjohnny

    Thread Starter Senior Member

    Jul 16, 2005
    142
    0
  4. mik3

    Senior Member

    Feb 4, 2008
    4,846
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    Yes, i am talking about this switch. As for the circuit this works on an astable mode, you have to build a monostable circuit.
    Look here for more information:

    http://www.kpsec.freeuk.com/555timer.htm
     
  5. ecjohnny

    Thread Starter Senior Member

    Jul 16, 2005
    142
    0
    Does this circuit work for me?
    http://www.kpsec.freeuk.com/projects/timer.htm

    i know i don't need the red LED and buzzer .

    All i want is the a lever switch connect to the 555 switch and output my transmitter.

    however if my transmitter have 9V battery. how can i use it also for the 555 timer? i mean combine them all up? hope you get me :confused:
     
  6. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    Just connect the 555 circuit and the transmitter on the same 9 volt battery.
     
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