How to Make an All in One Detector

Introduction: How to Make an All in One Detector

This is how to make what I call an "all in one" detector. It detects smoke, heat, and intrusion.

This is strictly a "for fun" project- don't actually use it as an actual burglar/fire alarm! (Needless to say)

I apologize in advance for my crappy camerawork...

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Step 1: Get a Battery Powered Smoke Detector

You can buy 'em anywhere. Just make sure you get one that isn't sealed- you need to get access to the circuit board.

Step 2: Smoke Alarm Components 101

Here are the basic components of your typical smoke alarm. The test button is just a little plastic button that when you push it, it causes the metal test switch to connect with a jumper tab, causing an alarm.

The piezo horn is what makes all the noise.

The ion chamber has 1 microcurie of Americium-241. It is what detects the smoke.

The status LED normally blinks every minute. When in alarm, it blinks every second.

I hope you know what the battery terminals are for...

Step 3: Make a Hole for the Heat Sensor

Start off with maybe a 1/4 inch hole. You can make it bigger if need be later on.

Step 4: Attach the Alarm Wires

These wires will trigger an alarm if shorted. So, solder them to either side of the test switch mechanism as shown.

Step 5: Dress the Wires

Well, this part is really optional, but it is highly recommended to avoid damaging the wires and possibly causing false alarms.

Step 6: Get a Heat Sensor

This you probably won't have laying around. I got this heat sensor from an old hardwired 12 volt smoke detector. It came from my old security/fire control system, and of course I have since replaced it.

If you have one, thats great. If you don't, well, you might be able to find something similar on the internet.

Step 7: Connect the Heat Sensor

Attach the two wires to either side of the heat sensor. Leave room- you will need to solder two more wires onto it.

Step 8: Connect the Other Pair of Wires

Connect another pair of wires to the same terminals.

Step 9: Get Some Magnetic Window/door Reed Switches

You can find these at a local security system equipment dealer.

Step 10: Attach the Other Pair of Wires

Connect them to the normally open contacts on your reed switch. You may have to check with an ohmmeter which ones are normally open. If you pull the magnet away, it should show continuity.

Step 11: Give Yourself a Pat on the Back

Good work. This device should now work properly. If you want, you can install a longer cable going to the reed switch, so you can monitor your bedroom window, or whatever.

Another thing you can do to make it an arm/disarm system-
Wire a switch between the reed switch and the heat sensor. That way, when the switch is off, it will not sound no matter what the condition of the reed switch.

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    9 Discussions


    7 years ago on Step 10

    can we use a battery instead of a reed switch? please answer fast


    9 years ago on Introduction

    Good try Wilbil808, I am using this with the help of Single phasing or power failure (3 ph) relay since May 2008 in my electrical department . If there is power outage it will raise alarm.


    10 years ago on Introduction

    If you use the flash on your camera, it will give a sharper image. Unless you're trying to photograph a reflective surface, then your damned if you do,and damned if you don't. ;)


    11 years ago on Introduction

    Just dont pop open that ion chamber and breath in all that americium dust... Thats no way to get high. Trust me.


    Reply 11 years ago on Introduction

    Lol, You sound experienced... nahh I hate ions anyway. Ions give too many false alarms. Photos are the way to go.


    11 years ago on Introduction

    This is so cool! Is there a way you could connect a camera into it to catch someone in act??