Hello to you all, For part of my BTEC final grade I have a project given to me from a range of 12 groups, out of the 12 I have chosen alarm systems. In particular I have chosen bike alarms, the idea I had in mind of how this system would work is to consist of a buzzer which is to be activated by a tilt switch, and deactivated by a key switch or another component, I would like the buzzer to stay on for at least 30 seconds or deactivated by a key switch and powered by a 9V battery. I would like to ask if there are any ideas or circuits that I could use as a guideline.

Thanks

 

What is BTEC?

 

Basicallly, it is a type of qualification in the UK, that specialises in a particular subject

 

High school? College? University? What does the acronym stand for?

 

The Acronym stands for: Business and Technology Education Council
This is for college

 

If it was me I'd use a small microcontroller. You could try Talking Electronics site I recall he has some alarm circuits.
http://www.talkingelectronics.com/te_interactive_index.html

 

I would like to ask if there are any ideas or circuits that I could use as a guideline.

There are many ways to do this. For example, look at sound activated switches/alarms. A momentary sound stimulous activates an SCR (silcon controller rectifier) which trips a relay or transistor to drive a buzzer. Your situation is similar, but even simpler since the tilt switch is easy to configure to directly trigger the gate of the SCR. Once activated the SCR stays on until the main current path is broken. This is where you can put your keyswitch in. A timer can also break the path using another transistor.

However, this may be too simple to use as a project, unless you are creative and go beyond the basic idea. Perhaps you can consider details for how to prevent false triggering, or tampering/deactivation. Maybe add a recorded voice that scares the thief away. "Warning ! Your picture has been taken and transmitted to a remote storage location."

If this is still too simple, maybe work in autodialing by cell phone to the police with transmitted message and GPS location, or a call to yourself so you can run out and crack their skulls open.

 

The Acronym stands for: Business and Technology Education Council
This is for college

In India BTEC stands for Bachelor OF Technology.. strange courses there..

And as for a circuit, there are lots of different circuits floating on the net, give it a google..

 

pull a mercury switch out of an old humidistat, wire it to a 555 in monostable with a puhbutton for reset, then an off/on switch to place it in alarm mode.

 

Look here.
http://www.zen22142.zen.co.uk/Circuits/Alarm/motorcycle.htm

 

If it was me I'd use a small microcontroller. You could try Talking Electronics site I recall he has some alarm circuits.
http://www.talkingelectronics.com/te_interactive_index.html

That website is very good to be honest, and I am very keen in using a microcontroller which is being creative rather than a simple circuit. Would is be possible if anyone could give me some guidelines of how I would go about programming this circuit, i.e which PIC, which components I should take out/include and a rough idea of what the programming would include.

Thanks

 

I can't help with a specific PIC but you want one that will do, at least, the following:

1. Run off 14 volts (or use a regulator).
2. Provide an input for each sensor you want to use (tilt, sound, etc.).
3. Provide an output to drive a siren (may need a buffer transistor).
4. Provide an output that can be used to disable the ignition (drive a relay, etc.).
5. Provide an output to drive a blinking LED.
6. Provide inputs for enable and disable switches.
7. A method to time how long the siren blasts (either a timer or a loop in the code).
8. A method to time how long the siren pauses before it blasts again and how many times it blasts before it shuts off for good.

Just my thoughts.

Jack

 

I am now back in college and I have to start this project properly, I have analysed everyones replies and willing to implement them in my circuit. As a starter I need a vague circuit layout of where these components would go and if there are any more ideas I can add to it to make it more complex but not too much.

 

I have done research on finding a template for this type of circuit which is attached, the only problem I am having now is how to go about placing the extra components into the circuitry since as we have not been taught about circuit theory so I do not have a clue where to start. It will be nice if you could give me some ideas so I can implement them.