Announcement
Collapse
No announcement yet.
I Need To Trigger a Relay When an LED Lights Up On a Smoke Detector
Collapse
X
-
I Need To Trigger a Relay When an LED Lights Up On a Smoke Detector
---------------------------------------------------
Jean-Marie G. Vaneskahian
jean@vaneskahian.com
---------------------------------------------------Tags: None
-
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.
-
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.
Comment
-
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.
Comment
-
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!---------------------------------------------------
Jean-Marie G. Vaneskahian
jean@vaneskahian.com
---------------------------------------------------
Comment
-
pp
-
Originally posted by jon00One 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:---------------------------------------------------
Jean-Marie G. Vaneskahian
jean@vaneskahian.com
---------------------------------------------------
Comment
-
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.---------------------------------------------------
Jean-Marie G. Vaneskahian
jean@vaneskahian.com
---------------------------------------------------
Comment
Comment