February 14th, 2008 |
HEY! So. I made a simple DIY home security "burglar alarm" for our house. We just got a brand new front door at theWAREHOUSE house and I've been thinking a lot about home security. There are a couple reasons for this project. One is, yes, it does help make a home more secure. But also it's a good very simple project with which to get used to my brand new soldering iron.
For a real and actual monitored security service (obviously a better, more comprehensive choice), you really can't go wrong in the classic ADT home security.
Really I made one of these as a kid, either in scouts or just as my dad was teaching me about electricity. It really is a great project for kids as it deals with a simple broken circuit. I wonder if parents still teach kids about engineering and thinking?
Anyway. What we're building today is basically a battery-powered electric buzzer. A simple clip creates a break in the circuit. When the clip is removed, the circuit's completed - setting off the buzzer. Check out the basic action below:
In case you weren't aware, it might be loud.
Here's what you'll need:
- block of wood to secure parts on
- 9-volt battery, or 2 AA batteries (or whatever powers your buzzer)
- wooden clothespin
- metal (brass) thumbtacks
- miscellanous short pieces of wire
- soldering iron and solder
- miscellanous: string, a wedge/clip, a suitable cover, small nails, etc.
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Above is a simple schematic describing the entire project. It really couldn't be much simpler of a project. It's not challenging - just interesting.
The project is not in figuring anything out, but in simply constructing it.
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Depending on the status of your junk drawers, the electric buzzer might be the only piece of equipment you actually need to buy. I picked up the buzzer in the above picture from Radioshack for about $3.50. It comes with those wires already sticking out of it. It's rated for 75db, which is not extremely loud but certainly quite loud enough to alert you to the door being opened. In addition it gives someone entering a certain cause for concern - you're obviously in charge of your house! Radioshack also sells a buzzer that's rated at 100db, but the store was out of them when I checked.
Also in the above picture is a AA battery holder I salvaged from something years ago. This was a perfect time to use it. The buzzer I picked up made the same amount of noise whether it was hooked up to a 9-volt or a pair of AAs, so I decided to use this for the simple reason that I had it.
Here I'm marking off places where I want the components to be located on my board. I pre-drilled holes for the security buzzer, and drilled holes to securely tie down the batteries - I decided against anything permanent in case I wanted to reuse the casing later.
Next up comes making the spring-loaded break in the circuit. Check out this picture below.
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DO NOT DO THIS! It's just a waste of time. Do you know why? I'll save you the trouble that I went through, thinking this little butterfly clip would be perfect. It's metal. There's no break in the circuit because the whole piece conducts. I picked up a package of a couple dozen wooden clothespins for, maybe, two dollars.
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Put a brass thumbtack through each front edge of the clothespin - it does help to pre-drill as it's weak wood and might split. Wrap the leads of your wires several times around under the head of the tack before you push it all the way through, and secure it with a few drops of glue. Test regularly to make sure you're maintaining a good connection. Your buzzer must sound clearly when the clothespin is closed.
For maneuverability and in order to preserve the cord lengths coming from the buzzer and the battery holder, I used two extra pieces of wire for the clothespin assembly. I actually just harvested them from a strand of Christmas lights. Simple as that, and very easy to get plenty of lead wire to work with as it's fairly easy to strip. A small spot of solder will hold the wires together just fine.
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Here's just a false-color detail showing the connection and the break. The brass tacks are highlighted to show positioning. You can also see one of the nails I used to secure the clothespin.
In the above pictures, everything is well secured to the board. The buzzer has small nails going into pre-drilled holes. The battery case is securely tied with string. I dismantled the clothespin and pre-drilled holes through it and into the board so that it could get a couple very small nails and glue. It's possibly the most important part of the system - as its the one that gets pulled on when a door opens - so it needs to be secure!
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You're basically done, at this point. What's left is really installing it and then gussying it up so it doesn't look quite so ghetto. Once I had established how large the burglar alarm system was, I cut the board down to a manageable size. The height of a box of checks worked just fine. So I took the lid (of the box of checks), cut it down to size, and folded the flaps over. You need two holes in this cover. One is for the clip that keeps the clothespin separated. The second should be positioned right over the buzzer so that its sound is not impeded or muffled.
Pre-drill some holes through your board and then securely screw the burglar alarm into the wall, level with your doorknob.
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I gave the new alarm cover a coat of grey spraypaint followed by two coats of off-white. This helps it match the wall so it's not quite so obvious and silly looking.
The next part should be fairly obvious. What you need to do is attach a thin but strong string to the clip in your clothespin. The other end, simply, goes around the door handle. You want it as taut as possible while being able to get it off the door handle easily from the inside. My original thought for the other end was a cheap carabiner, which would would perfectly for a "handle" type door but my inside-door handle is a latch. This means that if the door hand is turned down instead of up, the carabiner will slip off and not get pulled. A simple loop at the end solves this problem so long as it's "set" into the ridge where the handle meets the door.
I used a thick pink plastic twine above so it would show up easily on the video. It also still had the carabiner. Since then I've replaced them both with a simple length of white string - harder to see and easier to keep on the door knob.
I will probably make one of these for both of my doors. Perhaps another for the garage door and fourth for the only ground-accessible window my house has. Since I already bought plenty of clothespins, the only actual cost to me is the buzzer. So for under $15 I can have a lot of fun putting together simple projects to help secure my house.
Note that this DIY home security burglar alarm is obviously not the equal of a wireless store bought home security system, or a professionally installed and monitored system. It also only costs a few dollars. Clearly you need to weigh your options. The crime rate in your area, the security of your home, your ability to defend it - all of these need to come under serious consideration. In our situation we have a large dog, a low crime rate, and a very light sleeper. This DIY security system is an addition to our current security considerations.
Feel free to leave questions and comments. Please also feel free to rate the youtube videos I posted, and also to check out this site's other articles and advertising sponsors. Share with your friends!
Finally, for a real security system, check out the ADT alarm.
Next up, I wonder if I can hook up my old broken digital camera downstairs to a monitor in my room?
The End
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