I am looking for a low cost smoke detector that will open a normally closed loop when triggered. I may also need a CO detector so equipped. What companies make such a device and where can they be purchased?

I should also mention that I need the smoke detector to be battery opperated.

Bump.

FOr the most part, SMoke detectors run on an open loop. so what you would need would be a relay bridge to invert the output of the smoke from NO to NC. as far as the battery operation, you could look into (proffesional quality) smokes that are commonly used on residential (and commercial) fire alarm systems, these do run on 12VDC (and some 24vdc), and they also have N.O. output terminals, but again you would have to use a relay bridge to invert the output. The bettery operated smokes that you can get from your local hardware store, do not usually have output terminals, so to use one of these, you would have to monkey with the circuit board itself (which of course would violate any UL listing that might be applicable).

CO detectors are the same story, just a different flavor of detector. Although most CO detectors have both a N.O. output, and a N.C. output.

Hope this helps a little