Arduino fire alarm notification

Hello,

I just got myself some new fire alarms that can be connected together with a 2-wire cable, so that if one triggers they will all sound the siren. A quick test later I can tell they do this by applying 9v power from the battery directly to the cable. Simple enough to detect with a voltage divider and analog input on the arduino.

So, what if I'm not at home and there is a fire? I'd like to be alerted if possible. My thought is to use something like an arduino or similar and have it notify me by SMS, or maybe just e-mail (works almost as well with a smartphone these days). SMS will be quicker since e-mail requires my phone to check for e-mail first, but it's a cost vs. speed issue really. There are planty of automation apps for android out there that could sound the alarm when receiving a certain message or from a certain number. The arduino would be powered by a wall wart, and maybe I'll add a backup battery as well.

How would you go about to solve this? I don't mean in detail, but would you use arduino with SMS shield? Do you see any major problems with my idea? Got ideas of how to improve the sollution? Does it all sound stupid? Is there a cheaper sollution? Let me know. :)

Thanks,

Martin

Fire alarm or do you mean smoke alarm..??

If the latter, many have an alarm terminal that can be run to a relay (same manufacturers) ...used in commercial premises such as hotels or backpacker accomodation ..I think from memory called egress systems.

When smoke is detected, the alarms(all interconnected) are enabled and the egress system relay energises emergency escape route lighting. The relays have voltage free contacts so perhaps you could interconnect this to your arduino sms.

Well yes, they are smoke alarms, sorry. Here in sweden they are called fire alarms, if you do a direct translation.. :)

As for the terminal for interconnecting the alarms, I did describe that in my post above. They give out 9V when the alarm goes off. Why should I use relays when a voltage divider would suffice?

A voltage divider will do it. Say two 10K resistors in series across the 9 volts. Then the - and center tap, + to the Arduino will be 4.5 volts on a analog input pin.

I was assuming you were using 240v alarms....compulsory here in Aus..... :grin:

A fire Alarm uses device connected to a central control box, a domestic detector uses a chain of devices with 3 wires +,-, interconnect. From what you describe, you have the domestic interconnected setup with 9v on the interconnect line. Out of a pure safety aspect, use the interconnect to trigger a relay or similar device then use the outputs of the relay to trigger the pin on the arduino.

(IIRC) some makes and models may have an auxiliary interface module that you can connect to run and protect the arduino.

Pinky:
Do you see any major problems with my idea?
Martin

Yes. What if your Arduino catches fire? :grin:

bluejets: I was assuming you were using 240v alarms....compulsory here in Aus..... :grin:

Uh what they are!?! Omggggg I'm gonna die!!!!!

Suppose the fire breaks out at the fuse box or in a backroom the smoke alarm does not go off but the fire trips a fuse killing the detector...

I'm off to buy a battery operated one!

A zener diode will ptotect your arduino if you don't like resistor dividers.

Take it easy cjdelphi, your lack of knowledge is showing.

The 240V alarms have an internal battery backup system, the latest of which are 10 year life span.

I could go in to more detail about operation, voltage levels, how the interlink works etc but I think the original post has been catered for as it appears he has strictly battery alarm and his queries have been answered.

bluejets: Take it easy cjdelphi, your lack of knowledge is showing.

The 240V alarms have an internal battery backup system, the latest of which are 10 year life span.

I could go in to more detail about operation, voltage levels, how the interlink works etc but I think the original post has been catered for as it appears he has strictly battery alarm and his queries have been answered.

Well duh, and don't tell me to take it easy when I was taking it easy.... you lack a sense of humor .

And so what if they do have a backup battery? Is there a circuit inside to check the battery to make sure it's ok? Just how much knowledge do you have about smoke alarms?

So please recorrect your sentence...

"Your lack of knowledge concerning smoke alarms is showing"

Then yeah you're right, I did not know I had to design and build them to make a comment here, could you also explain how the circuit to detect smoke works... or will your lack of knowledge show?

Yes there is a circuit inside to tell if the backup battery needs replacement and they certainly let you know when this occurs, impossible to ignore.

Yes, there are 2 types of domestic and commercial smoke alarms. One uses and ionization technique( which involves a minute amount of radiation) and the other is photoelectric detection.

Here is a suggestion. Why not attach a microphone to the arduino and have it SMS of email upon hearing the correct frequency?