HOW TO: DIY an anti theft alarm system with pocket money (soldering skills needed)
 

Scared of losing your precious beloved to thieves but cannot afford or don`t want to pay huge money for an anti theft system? Well, you can make one yourself!

DISCLAIMER: ANY AND ALL ATTEMPTS TO BUILD ANY OF THE DEVICES SHOWN HERE HAPPENS SOLELY ON YOUR OWN CALL! THE WRITER OF THIS TOPIC TAKES NO RESPONSIBILITY OF ANY POSSIBLE DAMAGES CAUSED TO YOU, YOUR BIKE OR ANY OTHER PERSON OR PROPERTY!

In other words: if you pick up the solder iron from the table and wonder why it`s burning your hand, look away now...

Right, to business. The first version shown here is basically just a test platform, my notelist and the basic spine of the alarm system, it does function if assembled as instructed however it lacks two key attributes that are added on later versions: the startup delay and the alarm delay, in other words the bike needs to already be on it`s side stand BEFORE the ignition is turned off, and the alarm shuts immediately when the bike is lowered back onto the side stand after it is triggered. This version can be built with automotive relays but on the advanced version they are going to be changed to reed types cause they need 1/10 of the power to be operated and that way I can use a simple capacitor delay instead of a delay circuit.

But anyway for anyone who`s interested, do carry on reading cause updates will come as soon as I get things tested and the values of components dialed in. I`m planning to fabricate a circuit board for the final product and might be able to duplicate it for a small group of interested users somewhere in the (hopefully not too) distant future. This will be a universal model that fits any and all motorbikes that use a 12 volt system, but naturally I will be using my F2 as a test platform.


The backbone, heart and sould of the whole unit, and any other commercial unit is actually just one very simple component that has many different names, probably the most common ones being a tilt sensor or a mercury switch. It can look like something like this:


http://www.vekoy.com/images/AM978.gif

here are a few different versions I found today from an electric component shop:

http://kuvaton.com/k/YeL3.jpg

Essentially it is a small glass tube with two electrodes and a small drop of liquid mercury (or a steel ball on units manufactured after 2006 like in the black box) When fixed in a right position on a motorbike the mercury drop stays on the far end of the tube when leaning on the side stand and slides to the other connecting the two electrodes when the bike is lifted upright. Can`t get any simpler than that.




Here is the first schematic:

http://kuvaton.com/k/YeLn.png

The system is designed so, that the first switch- (or an opening type) relay arms the system when the ignition is turned off, and if anyone lifts the bike upright after that, the siren (or the bike`s horn) will start to scream and the high beam flashes on and off. I`m trying to build it so that the stanby mode will use as little power as possible, that scema displayed above will use precisely zero power until triggered but I`going to have to add two fairly large capacitors to the circuit that will drain a miniscule current to be preloaded.

As said this is basically just the first crude and simple version without any extra things, just the backbone, the advanced/evo(x) version will have a delay of about ten seconds that gives you time to put the bike onto the stand before the system arms itself, and another delay that leaves the siren and lights going for about ten seconds after the bike has been laid back onto the stand.

Already have a new soldering station and a bag full of components bought today waiting for some spare time!

stay tuned for more!

this looks very promising Mattson!

Nice work Mattson!

I'm curious as to the overall size of the package and where it can be stowed on the bike

That's one of the reasons I'm going to be using reed relays: cause they are a fraction of the size of an automotive relay and can be mounted straight to the circuit board. The only large bits are going to be the two big capacitors and a few relays but they are going to be fitted to the ends of some wires instead of straight to the board so they can be scattered around if need be. On my F2 I was thinkin of putting the device into the little compartment in the battery casing where I believe once was the original toolset. Quite naturally it's impossible for me to compete in size with the commercial versions cause they are made with those tiny little surface mounted components on at least dual layer boards, usually on both sides and usually microchip controlled that drops the needed board space to less than half again

Looks good Mattson. Once you hammer out those final details, I'll look into it ;)

http://kuvaton.com/k/YerB.jpg

Updated schematic, if there are electricians watching and someone spots a flaw or something that could/should be done better/otherwise, criticism is warmly welcomed.

EDIT: started thinking does the alarm trigger delay circuit have to be so complicated, shouldn`t it work like this just aswell:

http://kuvaton.com/k/Yer2.jpg

In this version the condensator should also give the trigger mechanism a sort of a schmitt-trigger effect and fool the thief at first that there`s no alarm, that should further enhance the scare effect when it goes off.

Nice one Matt, the old mercury switch was my first thought as well.

Also Dram if you can rig up a security light with a motion sensor it will also put them off.

As already mentioned, thieves will target the easiest/most vulnerable bike. The trick is not to be at the back of the herd when the wolves attack.

This is probably going to be a little irrelevant and off topic, but I learned in school that you can splice the high beam headlight circuit into the ignition relay circuit so that the bike won't start unless the high beams are on.

Once the bike is started then you can turn them off, oratleast back to low, it just wont start unless you have the high beams on. Like a hidden kill switch.


Not really that great of an anti theft system but not really something anybody would ever think of while trying to steal a bike so it could work. Really simple to do too.



I dunno, just throwin' that out there.

Why not, that would surely help. Can you do a wiring diagram of it cause I`ve been thinking about it the whole day and can`t figure how to do it without causing problems.

Prolly gonna continue with the alarm project tomorrow, don`t have time today cause I`m fitting new bars to my f2 cause it has promised rain for tomorrow.

Been on vacation a week and then several days catching up, so just tuned back in here.

Thanks Mattson. I'll print out the schematic and hit Radio Shack in the next couple days and begin assembling things. Should have it in place by next Friday. I'll let you know how it works.