How do I enable an existing 2 tone hard-wiren horn siren?

I need some help and please forgive me if this is NOT the correct forum to post this request.
I discovered an old hard-wired security left by previous owner a ELK SS-15 horn type siren in attic. I just checked by connecting it to a 12V supply and it works.
I’d like to use that as my siren for my SmartThings. Here’s my need in more detail below. Wondering if folks can guide me?

  1. There’s a switch which lights up attic light. I can possibly use that but will need to drop 120V to 12V DC.
  2. Even if I do it, I’ll still need a way to switch on the 12V DC via SmartThings.
  3. The horn has 3 wires - Yellow Steady Tone (+), Red Yelp Tone (+), White Common (-).
  4. Is there a way I can make it work actually like a police type siren? i.e. WOOO–ooo_WOOOO–oooo, etc.

I found this site : Wondering if this would help? But in this case, I don’t think I can opt for point #4 above? What’s actual an yelp tone, btw?
Also - is there any program way to switch on relay for 3 seconds, switch off for 1 sec and switch back on? Then possibly I can achieve my #4 objective?


The aeotch relay has 110 V output (not 12V!). THis will probably break the siren.

I think this is what you are looking for (a dry contact relay):

This app can probably do the siren for you. It takes a bit to learn how to use it but I think it is what you are looking for:

If you have an outlet in the attic you could put a smart receptacle in the attic, with a 12v plugin “wall wart” and simply control the receptacle with your SHM, or whatever.

I have a similar set up in my garage with a 12v led bulb using a receptacle and an old 12v camera power supply. When the system is armed I turn on the receptacle and the led is on…serves as a visual reminder when I enter the garage tha the alarm is on. Disarm turns the plug off.

Works great…receptacle was about $33.