Smoke Detector Alarm




About: I like to take things apart, see how they work, then put them back together; Or mod them to do other things. My hobbies are fulfilled with electronics, computers, making things, and lots of other things that...

A simple alarm made from a smoke detector.


Step 1: The Test Button

Find the good old test button on your smoke detector & pop open the case.

It's usualy a good idea to test the smoke detector first to insure that it is in working condition. -=p

Step 2: Step 2

Once you have opened up your good old noise box (smoke detector)
look inside to find the test contacts.

Ok, you see the lil buggers kinda tight area they're in too.
no prob, just use a pair of small needle nose pliers to bend the contacts into the position shown below in one of my pics.
Just follow the descriptions on the pictures.

Step 3: Step 3

Find the battery contacts, then attach a wire to the +Positive CONTACT & run that wire out through a small hole usualy in the detector.

THEN attach a wire to the (+) Positive TERMINAL of the BATTERY then connect the -Negative TERMINAL of the BATTERY to the corresponding CONTACT.
just plug it in, follow the wiring diagrams below.

If you've done it correctly when those two wires that you attached touch each other the alarm should sound.
(VERY LOUD) Gigity!

Step 4: Now for a Trigger!

Now find a suitable way to set off the alarm, Pressure switch, push button, Reed switch (my fav), or door switch (same as a reed switch but better for mounting on doors/windows.

The pictures below show a couple of the switches I used below to sound my alarm.

First one is the door switch (obtained from an unused security system in a wharehouse)pic1 shows door switch off pic2 shows it in the on position. -=p

Second is my Favorite it's a "REED" switch,Just wired one of those things up inside a DVD case & I used a magnet inside of an old newport box simple yet effective. -=]
When the 'Ewport' (not a typo) box was picked up the alarm would sound, It helps if you run long wires from the detector & hide it much funnier.

I made a stash box version of this alarm using the pressure sensitive switch out of an old phone hangup button I'll be posting it soon.

Well have fun with it as you may, just be careful these things contain RADIATION, So don't go putting it around young children or animals NOT COOL!

Feel free to ask me if you have a question about anything posted.



    • Classroom Science Contest

      Classroom Science Contest
    • Woodworking Contest

      Woodworking Contest
    • Colors of the Rainbow Contest

      Colors of the Rainbow Contest

    9 Discussions


    2 years ago

    thank you for this I have a methhead problem in my toolshed and this alarm will be very helpful!!

    1 reply

    10 years ago on Introduction

    PERFECT! This is just what I was looking for. I don't know why I did not think of it. This has all the parts needed for tons of tricky little things. I am going to use your idea to alert me and my grandchildren when a squirrel is inside of our glass squirrel feeder. Thanks


    10 years ago on Introduction

    need your help. I need to build a door close reminder. I keep leaving the front door to our apartment ajar and the wife keeps yelling at me. ok, when a smoke alarm battery dies, it chirps.How can i use a reed switch to fool the smoke detector guts into thinking the battery is dead/dying and start to chirp when contact is broken at the reed switch? I don't want the alarm to sound as if detecting smoke, just chirp If you can think of a better way to achieve this of course let me know


    10 years ago on Step 4

    Sorry for the delay in response..(relocating issues) But the alarm described cannot be used as a smoke detector with this configuration. Because when power is switched "ON" (Via trigger/switch) to the device the "TEST" button outputs the power to the siren. Thus bypassing it's smoke sensor that would usually trigger the siren.

    RGM La Paz

    10 years ago on Step 4

    does the smoke detector work as a smoke detector and a alarm also


    11 years ago on Introduction

    I'm the :none smoker: Note the term "EWPORT". -=p