CO Detector Wall Safe: Hidden in Plain Sight!

Sunday marked the first day of daylight saving time. In addition to turning back the clock an hour, it’s a great time to change the batteries on your smoke alarms and carbon monoxide detectors and also check to see if they need to be replaced! Our CO detector was getting close to 10 years old, so we replaced it with a new one.

Birdz of a Feather has always focused on upcycling whatever we can, so instead of throwing the old CO detector away I had an epiphany about using it to create a place to hide my valuables in plain sight! Sometimes necessity – and a penchant for upcycling – is the mother of invention!

The Back Story

When I was a teenager, my dad took me out to pick up a prescription at the drugstore leaving my Mom and the dog at home. In the span of no time at all an intruder kicked down the door and made off with all my Mom’s jewelry (including my grandmother’s jewelry which my Mom inherited when she passed away). Luckily my Mom had let the dog out and kept her company in the backyard just before it happened. Thank goodness for small favours; I shudder to think what would’ve happened if the intruder found my mom still in the house with the dog going nuts outside!

Since then I’ve always been wary about leaving valuables and sentimental objects around the house. Instead I put all my stuff in a safety deposit box which kind of defeats the purpose of having it in the first place. It’s an inconvenience to have to go get something when I want it, so I rarely wear and enjoy my nicer pieces of jewelry.

My epiphany about creating a secret hiding place was a long time coming. I think it’s a great solution for keeping some of those pieces near yet safely out of sight (and reach) from those they don’t belong to! When intruders have precious little time to ransack, they probably aren’t going to inspect all the CO detectors and fire alarms while they’re busy searching all the obvious places in the house first! And sometimes it isn’t even strangers that make off with our prized possessions; my sister once had something taken during a get together at her home. That instance had a happier ending: she confronted the person after the fact and got back what was taken.


Do not, under any circumstances, leave wires connected to the circuit board and/or plug it into a live outlet if you plan to make this project and stow your valuables inside the unit. You could cause a fire!

Once everything is stripped off the circuit board (the canister, alarm, power adapter and battery connection) it’s perfectly safe to use because it’s effectively dead. I put the circuit board back into the shell because it holds the display and tester buttons and helps make my CO detector upcycle look like an authentic working unit. The goal here is to fool intruders… not burn down the house where you, your loved ones and your valuables reside!

Watch the Video

In under 2 minutes, you can watch the video to see how it’s done and subscribe to my YouTube channel while you’re at it 🙂

You Will Need:

Step 1: Remove Battery Cover

Turn the CO detector over and remove the battery cover.

Take out the adapter plug by depressing the clips holding it in place.

I find that holding it upside down while depressing the clips is the easiest way to get it out (gravity does most of the work).

Step 2: Separate Front and Back

Locate the screw that’s holding the centre post; you may have to punch a hole through the lable to expose it.

Remove the screw then pull apart the front and back so you now have two pieces.

As you may notice, I actually got ahead of myself and pried the front off the back BEFORE I removed the screw. It was held in place by four posts on the corner and one in the middle (which I didn’t realize until after I ended up breaking off the centre post which was permanently attached to the front).

In the picture below, you can see the crack and small hole left on the front in between where the buttons go.

If that ever happens to you, just remove the screw from the post to release it, then glue it back onto the front with an industrial strength glue such as E6000 (I didn’t glue mine back together until after most of the video was shot).

Step 3: Remove Circuit Board

Remove the circuit board so you can desolder the joints holding the canister and alarm onto it.

Step 4: Prepare Work Surface to Desolder

Place a sheet metal pan on your work surface (ideally outdoors if you can) and gather up the soldering iron, solder pump and circuit board (solder side facing up). Heat up the soldering iron.

On the back of the circuit board, determine which connections you need to remove the solder from.

Step 5: Heat Solder Joints

Do this step in a well ventilated area!

Depress the solder pump to prepare it and keep it in your other hand. Place the soldering iron over one of the solder joints to melt it.

Quickly move the solder pump into place over the melted solder and squeeze the trigger. It should suck the solder out of the connector.

Once all the solder has been removed from the connections, you’ll be able to lift off the canister and the alarm (you won’t need these pieces).

I got tired of removing solder so didn’t end up removing the wire holding down the canister. No biggie: I merely bent it out of the way after removing the canister and flattened it. There was some foam tape under the canister holding it down, so I removed it.

Step 6: Cut ALL Wires

After the canister and alarm are removed, you can continue to desolder the wires for the power adapter/plug and battery, but an easier and faster way to remove the wires is to cut them off with wire cutters.

As I mentioned in the disclaimer, don’t leave any wires connected.

Step 7: Empty Shell

Remove the power adapter so you have nothing but an empty shell. At this point, you can reinsert the fully stripped out circuit board.

You can replace the tester buttons onto their posts too – or leave them until after the new digital display has been attached in the next few steps.

Step 8: Print New Number Display

I measured the size of the digital display on the CO detector then used Photoshop to design a new red-on-black print display with 0.0.0 instead of 8.8.8. I printed and then cut it out.

Step 9: Gather Up Valuables and Tape on New Display

Gather up all the items needed for reassembly: C02 detector body, film to cover the alarm sounder, your valuables, and some metal shutters removed from two floppy disks (these will serve as money clips to hold the bills inside the largest compartment – over the circuit board).

Step 10: Cover Alarm Sounder Window on Front

Since the canister is now gone and you don’t want to see into the space when your valuables are going to be hidden, use a piece of red film to cover the alarm sound window (shaped as an ‘N’) on the back of the front cover.

I used double sided tape to hold the film in place. You could also use something black (like a piece of cardboard), the colour of the canister. I just used what I had on hand and thought it would look nice to coordinate with the red CO detector display window instead.

Use double sided tape to stick the new display over the old one.

Here’s how it will look with the front in place:

Step 11: Dry Run to Test It Out

As shown on the video, I put the circuit board back into place, but before reassembling everything permanently, I rolled up some money and did a dry run to make sure it would fit inside. I used the metal shutters from the floppy disks to hold the folds of the money on both ends after I rolled it. You could substitute paper clips if you like or use nothing at all and just pop the lid on to hold it in place.

I then took it all apart again so I could make use of every inch of space and store some jewelry in the compartments too.

Step 12: Add Jewelry Storage

I removed the ring holder from an old jewelry box.

I found that it fit perfectly into the compartment that used to hold the power adapter plug.

For demonstration purposes on the video, I put a necklace into a plastic Ziploc and rolled it up; it fit into the compartment once used by the battery. There’s another compartment just like it on the opposite side that you could make use of too.

Step 13: Reassemble Front and Back

Once everything is placed, pop the front on and snap it shut.

Turn the unit over and replace the battery cover. You’ll find there is a gap where the power adapter used to be and see the back of your ring holder.

You can cover this opening with some cardboard – either before or after you insert the ring holder – just to keep the dust out (glue or tape it down).

After putting the battery cover on, you can replace the screw on the back which holds the centre post. However, the screw isn’t really necessary because the cover fits tightly anyway; leaving it off will give you quicker access since you won’t need a screw driver to get into your hiding place!

Step 14: Some Options for Hanging Your CO Safe

There are various options for mounting the unit.

Option 1 – Hang on a Screw

The back has two keyhole slots that allow you to hang it on a wall.

However, I find that one screw will suffice to hold it because there is also a slide support that helps hold it out from the wall to keep it plumb.

You can install a wall anchor before you put in the screw, but because it’s light I didn’t bother. The pictures below show further detail on installing a screw and using the slide support.

Option 2

With the particular unit I had, it can also be used on a table top. Just pull out the slide support and place it in a location of your choosing.

I’ve saved the best option for last in the next step!

Step 15: The Best Option

Option 3 – Create a Hidden Secret Safe with a Fake Wall Outlet

You could construct a FAKE wall outlet, pull the slide support out on the CO detector and hang it on the lower screw of the outlet to make it look like it’s actually plugged in. Just make sure that you use a longer screw for the bottom so it sticks out of the wall enough that it can catch the keyhole slot in the back of the unit.

An additional secret wall outlet safe is more work, but has two advantages: it will double up your storage space and look even more convincing! There are lots of how-to’s that you can search for online; you can see how to construct one in this post. Do not plug the unit into a live outlet (or even a switched outlet that could accidentally be turned on). The picture below shows the unit without its cover.

Whether you hang it on the wall…..

…..or the lower screw of a fake outlet, you’ll be keeping your money safe and close at hand for a rainy day! When you need access to your valuables, just remove it from where you’ve placed it and pop off the front.

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Check out these other recent innovations on Birdz of a Feather.

BYOB Upcycled Gift Bag:

This is great Christmas gift idea that’s made from a free reusable grocery bag; we probably all have extras lying around the home!

Plastic Clamshell Shrink Art:

This is a project that could be adapted for Christmas too; you could hang one on the tree for each family member!

In addition to home and garden DIYs, you’ll also find  crafts and recipes on Birdz of a Feather.

Shown below are a few DIYs, Crafts and Recipes on the site:

At Craft Rehab, I’m all about upcycling and crafting using unexpected materials:

Birdz of a Feather ~ Craft Rehab

At The Unknown Chef, I’ll show you how to ferment your own Sauerkraut, make a chicken soup that rivals any grandmother’s and cook BBQ chicken using a rotisserie:

Birdz of a Feather ~ The Unknown Chef

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Decoupaged Medicine Cabinet | Birdz of a Feather

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