this should do it - the micro controller should pair up as a switch - at that point the relay will act as if a user is turning the switch on and off using the siren.
if you do this get a relay with a harness on it so you can use wire nuts - I usually solder and heat shrink everything,you really donât need to do that.
Not sure how much power your alarm system is using with the siren going off but you can try this cheap Aeon plug in energy plug. Notify when power at a certain level.
Hi everyoneâŠThanks for the interesting projects to integrate and take over my ADT panel in the world of SmartThings, but I have to admit that those projects are far too much for me to take on right now. The spring chore list is far too long for me to take on another significant project! 
@pascal, when I get home today Iâll post a picture of the siren box and then Iâm mostly likely going to implement your approach of using the siren to trip the relay that activates the switch that alerts SmartThings. Itâs seems like the easiest way to go for right now to achieve the basic goal of letting SmartThings know when the ADT alarm goes off.
the siren looks to draw 150 mA @ 12VDC. Iâve tried doing these conversions in the past and found myself wrapped around the wheel on type of load and other details. wither way its going to be a really low number - I would be worried about monitoring at that resolution considering there are other things drawing power.
for what you want it seems like a good fit. The fully integrated solution looks super slick, though it will take a time investment that could be coupled with some frustration resulting in the need to allocate a beer budget. just saying 
The Leeo only picks up smoke and CO. It listens for their distinct tones. It most likely will not pick up an alarm siren. I have one and it works well but does not pick up either of my smartthings sirens as itâs not designed to.
Hello,
I purchased the Aeotech Microswitch G2 (model DSC26103-ZWUS), and wanted to utilize it to detect the opening/closing of a simple single-pole switch, and alert me to that opening/closing via Smartthings (via a text and push message). The end objective is to connect a relay in place of that switch, and have the relay activated by the 24 volt siren output of my alarm system (so as to alert me when the siren engages). The circuit I am trying to replicate is shown on the Smartthings forum, on the March 2016 date (you will see a schematic shown there kindly posted by pascal).
However, for the purposes of this support, please assume I have a simple single-pole switch connected to the âswitchâ contacts of the Microswitch. 110 volt power is applied to the AC power connections, and nothing is connected to the âloadâ terminals of the Microswitch. I simply want the Smartthings hub to detect the opening/closure of the switch and notify me, and I am having difficulty doing this.
Smartthings has notified me that they do not support this Microswitch, and instead support the original Aeotech Microswitch part number DSC18103-ZWUS. I assume this is the device configuration set up in my Smartthings profile.
The Microswitch is confirmed to be connected to the Z-wave network and Smartthings hub. I am able to activate the Microswitch by pressing the âon/offâ button on my cellphoneâs Smarthings device page, as I can hear a relay clicking inside the device when I turn it on/off. However, as described above, this isnât the functionality I am trying to create.
I have reset the Microswitch (pressing and holding the button down for 20 seconds until the LED blinks rapidly), but still cannot get the Microswitch and hub to detect the switch opening/closing.
Can you please confirm if there is a way for this to occur? Are there any other tests I should be doing to resolve this?
Any guidance would be greatly appreciated.
Thanks
Jason
I think the sound solution would be great for renters who probably donât want to/arenât allowed to mess with the alarm.
Did anybody come up with a good sound sensor solution? This is a great idea. I have a 2GIG GC2 alarm panel (alarm.com) that I no longer need monitored, but since I own the equipment, it would be nice to get an alert if it goes off.