Here's an example. I am looking at installing CO Experts carbon monoxide detectors in my house because they give *instant* alerts instead of the potentially several hour delay that UL listed devices give. They do not currently make a model with alarm contacts on it (but will next year). The red status LED only turns on when the device is in the alarm state. So, on the positive leg of the LED, we can splice in a transistor like this and have our alarm contact:
http://www.rason.org/Projects/transwit/transwit.htm
Of note, I have not tested this yet. But the engineer from CO Experts says that it is certainly possible. I might have to put a very low current relay in the mix also. But, if this works, I could use hook my ELK up to a bunch of stuff, including the low salt LED on my water softener.
http://www.rason.org/Projects/transwit/transwit.htm
Of note, I have not tested this yet. But the engineer from CO Experts says that it is certainly possible. I might have to put a very low current relay in the mix also. But, if this works, I could use hook my ELK up to a bunch of stuff, including the low salt LED on my water softener.