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I Need To Trigger a Relay When an LED Lights Up On a Smoke Detector

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    I Need To Trigger a Relay When an LED Lights Up On a Smoke Detector

    jean@vaneskahian.com
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    Jean-Marie G. Vaneskahian
    jean@vaneskahian.com
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    #2
    Do you have an Ocelot and Secu16? That would be my first choice for connection. After that, you can look into a Powerflash that will issue X10 On with your 1.78V and X10 Off with your near-zero voltage. Either method should only require direct connections of the two wires coming from the LED.

    The Ocelot/Secu16 input would be an analog input and would need to either have CMAX code written to set an HS variable ON/OFF using the analog value (recommended method) or creation of HS event that checks for the analog value changes and sets a virtual device.
    Jim Doolittle

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      #3
      I believe all you need is an optoisolator with a dry contact backside. Rocco pointed me to the H11F1 that I used to marry my Radar motion detector with a Window/Door sensor. The backside of the H11F1 (pins 4 & 6) went to the dry contact of the DS10A for RF transmission to the W800. The front side (pins 1 & 2) went to the voltage input. In my circuit the input was from a 555 timer pin 3 via 1 1K resistor. I suspect you can go directly from your led, but I know just enough to get my self in trouble so I would not take my word for it.

      For my vibration sensor interface I used a 4N26 with the backside to a MS13A motion sensor with the hack to convert the dusk sensor into a door sensor. The 4N26 is more available such as Radio Shack.

      I forgot where I bought the H11F1, but Digikey is a likely source.

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        #4
        Depending on the voltage supplied by the device that monitors contact closure (~15v or less), you may be able to use a 1k resistor and a generic NPN transistor. Connect the + lead from the detector device to the transistor collector, and the - lead to the transistor emitter. Connect one end of the resistor to the + side of the LED lead, and the end to the transistor base. Connect the transistor emotter to the - side of the LED. You can get 15 NPN transistors at RS for $2.49, and the resistors are 5 for $1.
        Why I like my 2005 rio yellow Honda S2000 with the top down, and more!

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          #5
          Thanks for the help!

          I will go with the simple advice of zoomkat and wire in the NPN transistor. I also appreciate the idea of the H11F1.

          I am trying to make all this wireless and I have the Caddx Wireless contact closure transmitteres that are monitored by the alarm system.

          Thanks again guys!
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          Jean-Marie G. Vaneskahian
          jean@vaneskahian.com
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            #6
            One other thing - It is always best to put a reverse biased diode across any relay which stops back emf from destroying the transistor. Something like:
            Attached Files
            Jon

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              #7
              Light sensor pad. Just put it over light.

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                #8
                Originally posted by jon00
                One other thing - It is always best to put a reverse biased diode across any relay which stops back emf from destroying the transistor. Something like:
                It works! Thanks... I now need to make a little circuit board with the components.
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                Jean-Marie G. Vaneskahian
                jean@vaneskahian.com
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                  #9
                  Mission Accomplished! I have a CO Detector Wirelessly Sending Out Status To My Alarm

                  http://www.aaroncake.net/circuits/relaytim.htm
                  http://www1.electusdistribution.com....d/relaydrv.pdf

                  Thanks again to all those that helped me!
                  Jean-Marie Vaneskahian
                  jean@vaneskahian.com
                  Last edited by jeanv; November 15, 2004, 08:33 PM.
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                  Jean-Marie G. Vaneskahian
                  jean@vaneskahian.com
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