Introduction: Assasin Door Securer

Are you a super-stealthy-diy-ninja Assassin or do you just want to know when you little brother's been going through your stuff again?

This Instructable shows you how to make a really cheap Door Securer, this project is great for kids or people with little electrical knowledge. It requires no soldering whatsoever, the materials are cheap and easily available, and you do not kneed many tools.

The Door securer is planted in the room you want to secure and then a thin piece of cotton or fishing wire is attached to the tab and the other end to the door. Then when someone tries to sneak into your room to assassinate/nick-your-stuff, the string is pulled and the little tab slips out of the box, this completes the circuit and the two led's flash to tell you someone has been in the room.

Step 1: Materials and Tools


There are 3 main components you need for this project ;
  • The Circuit
  • The Box
  • The String

The Circuit you need can be easily obtained from one of those musical birthday cards, Before you buy one look around your house, sometimes parents keep good birthday cards, or maybe you brother/sister has one you could buy with shiny coins or marbles.

The box, for my box i used an old Gameboy cartridge dust box thing. You could use the same or any other type of box as long as the circuit board fits inside. I would have used an altoids tin but it was too big for this project :P

The String, you could use either thin cotton or fishing line (ask mum for cotton, dad for fishing line), it needs to be light and quite thin so the intruder doesn't see it.

  • X-Acto knife
  • Wire cutters
  • Dremel
  • Paint brush (maybe)

Step 2: Opening the Card

Now you have your materials and tools together you need to get the circuit out of the card, to do this simply get your x-acto knife and slide it between the two layers of card and run it all the way around the edges, then open the flap of card and you should see your circuit.

Step 3: Sorting Out the Circuit

Now we have the circuit from the card we need to slightly modify it to fit our needs.

First we need to remove the speaker, you can simply cut it off with the wire cutters, but remember to leave a little bit of wire still attached to the circuit board. Now strip off any plastic covering and solder/twist the wires together to complete the circuit.

Now we have to add the LED’s, (my card already had two led’s attached so I didn’t need to do this part) You can add as many LED's as you want at this point, I recommend two LED's in different colours. Attach the LED’s “legs" in the order + - + - and solder them to the board.

Step 4: Remove Circuit

Now if you haven't already done so, remove the circuit from the card.
Using your x-acto knife carefully pry the board away from the card.

Step 5: Find a Container

Now we have the basic alarm circuit we need to find a container to house it.
You could use an Altoids tin but i thought is was a bit too big so i found an old game-boy cartridge case.

If you don't have a game-boy cartridge case you can use any other small container as long as you can cut/dremel through the material, once you have found your container place the circuit next to it to check it will fit, if it does move on to the next step.

Step 6: Dremel Dremel Dremel

Now we have the container for our alarm we need to create the hole in the side that the tab will go through, once we have done that we can also drill the holes for the LED's to poke through.

Place the circuit in the box and with a pen mark where the tab will come out of the box, now remove the circuit and power up your dremel, (i recommend using a diamond tipped cutting bit)
Now cut all the way through the container where you marked with your pen, stop every now and again and see if the tab will fit through, if it doesn't keep on drilling.

Step 7: Dremel Dremel Dremel .... Again....

Now we have the tab in place we can drill the holes for the LED's.

First you need to find the right sized drill bit, hold the end next to the LED, you want it to be as close as possible, maybe even a little bit smaller.

When you have your drill bit put it in your dremel and make sure its tight. You can drill the two holes anywhere you like on the box, i chose to drill mine at the top of the box.
Once you have drilled the holes use a small file or similar to clean up any excess plastic.

Now simply pop the LED's into the holes and use some glue to hold in place if they are a bit loose.

Step 8: Paint It !!!!

Now we have the basic door securer we can customize it. You don't have to paint it but it looks a lot cooler if you do :P

Now we want to colour our door securer, if you're lazy you can just use coloured tape but i wanted to paint mine.

First find your paint and a paint brush (obviously), then make sure your painting on a protected surface like a mat or some old newspaper. Then start painting, you may need to do more than one coat to get an even covering.

Once you have finished painting and it looks good you can either go to sleep or go out for about 6 hours whilst the paint dries, but if your impatient like me then use a hairdryer on a high heat setting :P
(i made a makeshift holder with various clamps so i wouldn't have to hold the hairdryer )

Step 9: Stick the Circuit Down

Now we have painted our container and the door securer is nearly finished we can glue the circuit down to stop it rattling around in the container. You don't have to use glue you could just use blue tack or sellotapeyea not "sticky tape"

If you are going to use glue then squirt a small amount under the circuit and then position it in the container. It would be a good idea to put a weight on top to keep it in place.

Step 10: Attatch to the Wall

This step varies a lot depending on where you are going to mount your door securer. My door has a light switch next to it so i decided i would use magnets to hold my Door Securer in place.

If you are going to use magnets then squirt a pea-sized blob onto the back of the magnet and then place the magnet on the back of the container.

Step 11: Tying the Knot

Now we just need to add the string to the tab.
You can use any type of thin thread you like, i used some thin cotton thread i got from a sewing box.
Cut a section of cotton off that will be long enough to reach from your Door Securer box to the door handle.

Now you have the string tie one end tightly to the tab poking out of the container and move on to the next step.

Step 12: Setting It Up

Now we have the finished Door Securer we need to set it up.

So first attach the Door Securer box to the wall near your door.
Then take the loose end of your string and tie it tightly around the door handle

Done !, your Door securer is in place and no longer will ninjas/little-brothers be able to creep around your room un-detected !

Continue to next step for videos!

Step 13: Videos !!!

Demonstration of the Door Securer

Quick look at the Door securer Lights and Box

Step 14: The End

Thats it, i hope you liked it.
Next time its your birthday you should think about trying this, its fun :P
If you liked this then you should check out my other instructables HERE

Leave a comment and vote for it in any contests its in lol :D